Home on codebase

useful add-ons

Fri, 03 Apr 2026 00:00:00 +0000

This is a collection of useful CLI utilities, which usually are not by default installed by GNU/Linux distributions.

starting Payara Micro

Fri, 21 Nov 2025 00:00:00 +0000

starting Payara Micro from the command line

Here are the command line parameters that I use most often when starting Payara Micro:

quick client setup walkthrough

Tue, 18 Nov 2025 00:00:00 +0000

This walkthrough is for a quick client machine network setup by hand. The examples are for a fictive client machine with the following client and network values:

boot process on UEFI platforms

Thu, 13 Nov 2025 00:00:00 +0000

The UEFI specification is no fun read and for some topics, I found it hard to understand. This document describes the boot process on UEFI platform from the moment a machine is powered up until the moment the OS takes control over the machine. I put this document together from information from the UEFI spec and some other sources. Running Intel CPU’s, I focus on the Intel platform here. Intel and AMD do take slightly different approaches during the early boot sequence, but the overall picture is the same.

ANSI escape codes

Wed, 08 Oct 2025 00:00:00 +0000

ANSI escape codes (more formally, ANSI escape sequences) are in-band signaling codes to control cursor location, color, and a bunch of other options on command line terminals.

psqlrc - the psql config file

Wed, 08 Oct 2025 00:00:00 +0000

The configuration file for is .

There are several options for the location of the system-wide :

adding ssh keys for comfortable push/pull

Fri, 29 Aug 2025 00:00:00 +0000

With your ssh public key registered with Gitea, you can push and pull to and from Gitea without being asked for your password for every action.

renaming the default branch of a repo in Gitea

Fri, 29 Aug 2025 00:00:00 +0000

I was already tired for a while that the default repo name in git was master. So I took the opportunity when updating Gitea to rename the default branch of the corresponding git repos to main.

run Gitea behind a proxy

Fri, 29 Aug 2025 00:00:00 +0000

This has the advantage that I don’t have to remember the port on which Gitea is running and can just type into my browser’s address bar.

run Gitea with TLS

Fri, 29 Aug 2025 00:00:00 +0000

You need two certificates: the certificate chain to the Root CA and the certificate for gitea. I’m running an own root CA in my LAN (mostly for fun and educational purpose) and issued a cert for gitea.

XBPS package manager

Tue, 19 Aug 2025 00:00:00 +0000

working with the XBPS package manager.

date/time

Sun, 17 Aug 2025 00:00:00 +0000

dateFormat works only for secific date

the following works and renders on August 17th, 2025, the string :

hugo new

Sun, 17 Aug 2025 00:00:00 +0000

rudolf@idoru:/opt/intra/site/dev/codebase/content/techdoc/frontend/hugo/code-shreds(main)$ hugo new section.md Error: no existing content directory configured for this project

only works as expected when invoked outside the content dir. Additionally, the page kind is not automatically resolved but must be given with the argument .

page

Sun, 17 Aug 2025 00:00:00 +0000

section

Sun, 17 Aug 2025 00:00:00 +0000

getting a section

{{- $rootSection := .Site.GetPage (print "/" .Section "/_index.md") -}}

string

Sun, 17 Aug 2025 00:00:00 +0000

concatenating strings

Strings can be concatenated with :

setting the system and hardware clock

Wed, 13 Aug 2025 00:00:00 +0000

TLDR? Head straight to putting it all together.

time formats UTC and local time; time zones

The world’s primary time standard is UTC, which is short for Coordinated Universal Time. UTC is defined as the time at the meridian with a longitude of 0°. It is the successor of GMT, Greenwich Median Time (Greenwich, UK, is located at the meridian with longitude 0°).

how to prevent your home dir from getting littered

Wed, 17 Jan 2024 00:00:00 +0000

For most Linux distributions, even in a pristine bare minimum installation, the home directory of a user is already littered with a bunch of files and directories, that contain program configurations, colloquially called dot-files. This gets worse over time, as more programs are installed and used.

switch

Tue, 09 Jan 2024 00:00:00 +0000

traditional switch statement

The traditional switch statement has a test expression and a switch code block. In a switch code block, only switch statements are allowed. A switch statement starts with a label and a value or a label, followed by a colon, followed by one or more statements;

basic git concepts

Sat, 28 Oct 2023 00:00:00 +0000

overview of a git repo

The following picture shows the structure of a git repo and illustrates the flow of data between the repo’s components. The arrows also illustrate the workflow when working with git, with each arrow labeled with the corresponding git command (i.e. add for the command git add):

editing EXIF data with ExifTool

Sun, 15 Oct 2023 00:00:00 +0000

so what is EXIF?

EXIF (Exchangeable Image File Format) is a standard format maintained by the Japan Electronic and Information Technology Industries Association (JEITA) for metadata in digital images. EXIF is used to tag image files with metadata like image width and height, bits per pixel, camera settings like shutter speed and a whole host of other image specific data like the GPS location where the image was taken, and the date and time when the image was taken. EXIF is supported by almost all modern digital cameras. It is also used to tag other types of files, i.e. sound files, PDFs, OpenOffice/LibreOffice or Word docs.

migrating Java Server Faces 2.3 to Jakarta Faces 4.0

Tue, 10 Oct 2023 00:00:00 +0000

Work in Progress – I’m still in the transition from Java Server Faces 2.3 to Jakarta Faces 4.0 and will add here whatever I will encounter.

Jakarta Faces 3.0 didn’t bring any new features or changes, but was just a renaming of the javax.faces namespace to the jakarta.faces namespace. So I did the migration straight from Java Server Faces 2.3 to Jakarta Faces 4.0.

migrating JPA 2.2 to 3.0

Thu, 05 Oct 2023 00:00:00 +0000

changes

There are no new features in JPA 3.0. The changes in 3.0 just reflect the transition from Java EE to Jakarta EE by renaming the prefix of the JPA API packages, renaming the prefix of config vars in config files like persistence.xml and introducing the new Jakarta specific namespace for XML config files. Additionally, avoiding the use of the name Java avoids legal issues.

Jakarta Faces performance tuning

Wed, 29 Mar 2023 00:00:00 +0000

approaches to apply right from the start

prefer HTML over JSF tags.
no logic in getters (can be called multiple times) – especially for the rendered attribute.
avoid logic in EL expressions.
avoid using h:outputText. instead, use an EL expressions.
if you need to escape HTML, it’s better to use an EL function.
use AJAX where possible.
only process and update components that are really required to be updated.
use where posssible. Avoid using , and other long lived scopes.

approaches for performance tuning

cache data, which is required multiple times in the same view, in @RequestScoped beans.
split your backing beans. It’s better to have a separate bean for logic and a separate bean for values which are required for multiple requests (, …).

a few JDK vendors and available JDKs

Mon, 05 Sep 2022 00:00:00 +0000

Some information on available JDKs and their vendors

Jakarta EE versions

Mon, 05 Sep 2022 00:00:00 +0000

Java EE and Jakarta EE versions

Java EE versions

Mon, 05 Sep 2022 00:00:00 +0000

Java EE versions

arrow brushes with GIMP

Thu, 14 Jul 2022 00:00:00 +0000

creating arrows for technical documentation with GIMP and draw.io

user management

Tue, 12 Jul 2022 00:00:00 +0000

overview of the WildFly role based access control structure RBAC and its configuration options

WildFly standalone installation

Tue, 12 Jul 2022 00:00:00 +0000

WildFly standalone installation and basic configuration walkthrough

the codebase site is up

Mon, 27 Jun 2022 00:00:00 +0000

What I wanted to do for a long time, but didn’t have the time to do (or I thought I didn’t have the time): I finally got this website up and running, with the blog you’re reading right now, technical documentation and my portfolio.

intro

Mon, 18 Apr 2022 00:00:00 +0000

Shell programming can be used to write shell scripts that simplify tasks that can be done on the command line. Shell scripts consist of a consecutive series of terminal commands and shell built-in commands. This documentation refers to bash, the bourne again shell.

output

Mon, 18 Apr 2022 00:00:00 +0000

For output, two commands can be used: echo and printf. Both commands are available as a shell built-in and/or

terminal input

Mon, 18 Apr 2022 00:00:00 +0000

User input from the terminal can be processed with the command read By default read reads user input from

variables

Mon, 18 Apr 2022 00:00:00 +0000

variable names

Variable names are case sensitive. They have to start with a lower or an upper case letter or an underscore.

Hugo misc stuff

Fri, 18 Mar 2022 00:00:00 +0000

this is a kitchen sink for stuff that I throw in, before I forget it, and to redistribute it later to the appropriate pages

context root

Fri, 28 Jan 2022 00:00:00 +0000

setting the context root in configuration files and on the shell when running Payara Micro

intro

Fri, 28 Jan 2022 00:00:00 +0000

The jshell is a great tool for exploring libraries, testing new features of Java and for explorative programming in general. Java code entered at the shell prompt or provided by script files is evaluated by the jshell in a Read-Eval-Print-Loop (REPL). No need to compile your code and start a jvm with your code (this is what the jshell in effect does).

jpa

Fri, 28 Jan 2022 00:00:00 +0000

setting up JPA with Payara Micro for access to a PostgreSQL Database

Payara Micro JAR folder structure

Fri, 28 Jan 2022 00:00:00 +0000

overview of the Payara Micro jar structure and options for unpacking the jar when running Payara Micro

tls

Fri, 28 Jan 2022 00:00:00 +0000

securing Payara Micro’s HTTP port with TLS (Transport Layer Security)

CDI with JSF 2.3 on Open Liberty

Fri, 21 Jan 2022 00:00:00 +0000

@FacesConverter does not work with the JSF 2.3 feature of Openliberty with a default config

configuring TLS on Openliberty

Fri, 21 Jan 2022 00:00:00 +0000

complete TLS setup for Openliberty with keystore creation and setup of Root CA

Openliberty JPA setup

Fri, 21 Jan 2022 00:00:00 +0000

required features

Java Database Connectivity

and one of the followoing features:

Java Persistence API, includes Eclipselink as provider, or
Java Persistence API Container, for other providers like hibernate plus a JPA provider

configuration

configuration files / locations

. ├── pom.xml └── src └── main │ ├── liberty │ └── config │ └── server.xml ├── resources │ └── META-INF │ └── persistence.xml ...

server.xml

In the server.xml, the required features are enabled, the location of the database driver is specified and the datasource is configured.

keyboard configuration

Thu, 20 Jan 2022 00:00:00 +0000

configuring the keyboard with a layout alternating between a primary and a secondary language

the debian way

Thu, 20 Jan 2022 00:00:00 +0000

installation of the JDK / JSDK – the Debian way

setup fs

Wed, 19 Jan 2022 00:00:00 +0000

how to set up encrypted partitions with LUKS after installation of the OS

running the HUGO server

Tue, 18 Jan 2022 00:00:00 +0000

how to run the HUGO server in dev mode, for deployment, and within scripts

configuration

Tue, 11 Jan 2022 00:00:00 +0000

some recommended basic configuration after the installation of PostgreSQL

configuring HAM for Payara

Tue, 11 Jan 2022 00:00:00 +0000

configuration of the Java Security API’s HttpAuthenticationMechanism on Payara

database and database objects

Sat, 08 Jan 2022 00:00:00 +0000

creating databases and database objects

psql

Sat, 08 Jan 2022 00:00:00 +0000

some useful psql commands for daily work with PostgreSQL

software architecture and development

Thu, 06 Dec 2018 09:29:16 +1000

In most projects I’m working 20% as an architect and 80% as a developer, building prototypes and POCs, implementing functionalities and reducing complexity.

Enerchain B2B trading platform

Sun, 18 Nov 2018 12:33:46 +1000

In the Enerchain project, I supported the B2B service provider Ponton, Hamburg, in setting up a decentralized trading platform for energy suppliers. Enerchain enables energy suppliers to trade anonymously with complete end-to-end encryption. Some of Europe’s leading energy suppliers, such as Enel, Endesa, Eon, RWE, and Vattenfall, participated in the proof-of-concept (PoC) phase of Enerchain.

GIS for supply chain management

Sun, 18 Nov 2018 00:00:00 +0000

I supported Navteq, a leading provider of geographic data for use in navigation devices, in the further development of a GIS (Geographic Information System). By partially restructuring the system, we achieved higher performance. In addition, several refactorings significantly improved the results of the VeraCode security audit.

blog

Mon, 01 Jan 0001 00:00:00 +0000

I occassionally blog about software development, focusing on the topics Java and Linux.

UEFI images

Wed, 07 Jan 2026 00:00:00 +0000

UEFI Images are a class of files that contain executable code, aka EFI applications. UEFI images can be loaded and executed by an UEFI firmware. The first set of bytes in the UEFI Image file contains an image header that defines the encoding of the executable image.

dhcpd setup

Tue, 18 Nov 2025 00:00:00 +0000

reached its EOL in the end of 2022 and is now superseded by .

One reason to use any longer is when a migration is to version 1.9.1 or later is not possible.

dhcpcd setup

Tue, 07 Oct 2025 00:00:00 +0000

(Dynamic Host Configuration Protocol Client Demon) is the demon responsible for querying a DHCP server (i.e., ISC kea) and configure the machine for the network it is about to join from the lease it receives from the DHCP server. A DHCP lease contains configuration values, i.e.:

git bash enhancements

Wed, 22 Jun 2022 00:00:00 +0000

how to customize git in bash for a more comfortable and efficient working experience

git configuration

Wed, 22 Jun 2022 00:00:00 +0000

configuration of git after initial installation with settings for users, repos and system wide settings

snippets

Fri, 28 Jan 2022 00:00:00 +0000

jshell accepts the following JLS syntax: Statements Expressions Variable, Method, Class and Interface

ram disk

Thu, 20 Jan 2022 00:00:00 +0000

mounting a ramdisk at boot up and differences between tmpfs and ramfs

debian fix

Wed, 19 Jan 2022 00:00:00 +0000

fix for stalled shutdown process on Debian systems with System-V Init

options parsing

Tue, 18 Jan 2022 00:00:00 +0000

There are several methods for the parsing options / parameters supplied to the shell script .

clean, elegant solutions

Thu, 06 Dec 2018 09:29:16 +1000

Elegance is not a luxury but a prerequisite for stable and equally flexible systems. Keep it simple stupid. This applies to both architecture and code. I always leave the campground cleaner than I found it.

payment services helpdesk app modernization

Sun, 18 Nov 2018 00:00:00 +0000

For Ingenico, one of Europe’s largest payment service providers, I developed a catalog of measures for modernizing a helpdesk application for first-level support. In doing so, I reviewed the frameworks used for the application in terms of their future viability, evaluated possible alternatives, and developed a decision matrix to assist the project management team in their decision-making.

techdoc

Mon, 01 Jan 0001 00:00:00 +0000

From time to time I upload technical documentation that I wrote while working on projects and evaluations.

Unified Kernel Images

Wed, 14 Jan 2026 00:00:00 +0000

A Unified Kernel Image (UKI) is a combination of an UEFI boot stub, a Linux kernel, and further (optional) resources like an initrd, all combined into a single UEFI image. This file can either be directly invoked by the UEFI firmware bootloader or by a bootloader like rEFInd or an OS’ bootloader.

wireless setup

Tue, 18 Nov 2025 00:00:00 +0000

preparations

check if wlan0 is powered up

iwlist wlan0 power

list available networks with iwlist

iwlist wlan0 scanning

generate config block for SSID with wpa_passphrase

wpa_passphrase computes a 256-bit PSK and generates a configuration block for the network with the SSID (Service Set Identifier) or ESSID (Extended Service Set Identifier) provided as parameter. For an access point with the SSID base, the command line is:

network setup with iproute2 and net-tools commands

Wed, 12 Nov 2025 00:00:00 +0000

In Linux, the network setup of a machine is done with the iproute2 tools. The iproute tools supersede the now obsolete net-tools, which include, among others, the well known , and commands.

history

Fri, 28 Jan 2022 00:00:00 +0000

history jshell maintains a history that includes all previously entered commands and snippets

diagnostics

Wed, 19 Jan 2022 00:00:00 +0000

how to run diagnostics of devices encrypted with LUKS

arrays

Tue, 18 Jan 2022 00:00:00 +0000

welcome to the world of negative indices and other barnyard oddities.

techstack

Thu, 06 Dec 2018 09:29:16 +1000

I work on Linux and my favourite setup for development is Intellij, Git and the Atlassian tools for collaboration: BitBucket, Bamoo, Jira, Confluence.

HMI software design and development

Sun, 18 Nov 2018 00:00:00 +0000

When Volkswagen developed its own car radio system, I joined the development team and was responsible for the AM/FM part of the car radio. An essential part of my development work was the integration of the RDS (Radio Data System). In cooperation with the on-site residents of the suppliers of the tuner hardware I developed the interfaces to control the tuner hardware.

roles (users)

Mon, 24 Apr 2017 00:00:00 +0000

creation and maintenance of users and roles, setting permissions for users and roles

who I am

Mon, 01 Jan 0001 00:00:00 +0000

I am a software engineer from Hamburg, Germany, working with Java.
Sometimes I scrub metal in the engine room (Linux) to create the infrastructure for projects.

setting the kernel log level

Wed, 20 Aug 2025 00:00:00 +0000

kernel log levels

Messages sent by the kernel fall into 8 categories of log levels 0 to 7, with log level 0/KERN_EMERG having the highest priority and log level 7/KERN_DEBUG having the lowest priority:

variables

Fri, 28 Jan 2022 00:00:00 +0000

Variables can be explicitly declared. For expression that don’t have a named variable, an implicit variable

blacklisting modules

Wed, 19 Jan 2022 00:00:00 +0000

two ways how to prevent kernel modules from being loaded at startup

key management

Wed, 19 Jan 2022 00:00:00 +0000

management of keys for partitions encrypted with LUKS

removable media

Wed, 19 Jan 2022 00:00:00 +0000

alternate mounting of several devices under the same mount point

udevil & devmon

Wed, 19 Jan 2022 00:00:00 +0000

using udevil and devmon for automatic mounting of removable media

2nd order reference

Tue, 18 Jan 2022 00:00:00 +0000

A 2nd order reference is a reference that references the variable with the name which is the value

gitignore files

Fri, 29 Aug 2025 00:00:00 +0000

Can be added to repos that are created with Gitea. gitignore files go into .

interface naming schemes

Thu, 21 Aug 2025 00:00:00 +0000

there are several naming schemes in Linux:

the “traditional” or “classic” naming scheme of the nineties with iface names eth0, eth1, wlan0, wlan1, etc. Interfaces get their names assigned by the kernel on a first-come, first-serve policy as they are probed by the network interface drivers. With nowadays complex hardware, this way of naming is no longer predictable if more than one interface of a kind (ethernet, wlan, …) exists in the machine.
some custom schemes working towards alleviating the problem mentioned above. Programs like and (which uses udev) used config files like and assigned interface names based on the MAC address – which comes with another set of problems. These custom schemes seem to be no longer in use.
the predictable network interface devices names introduced in udev. Note that udev is developed as a part of systemd but can be used completely without systemd (at least at the time of writing).

The authoritative documentation on the persistent naming on freedesktop.org is marked as obsolete and refers to the systemd.net-naming-scheme man page . Unfortunately, I can’t wrap my head around that man page completely.

XDG Base Directory Specification

Wed, 29 Mar 2023 00:00:00 +0000

XDG stands for X Desktop Group, a project to work on interoperability for free-software desktop environments for the X Window System (X11) and Wayland on Linux and other Unix-like operating systems. It eventually evolved into freedesktop.org. freedesktop.org produces specifications for interoperability, but it is not a formal standards body. Projects are not required to implement the specifications and there is no certification.

reverting changes in git

Wed, 22 Jun 2022 00:00:00 +0000

how to revert staged and unstaged changes while working with git

viewing git commit history

Wed, 22 Jun 2022 00:00:00 +0000

viewing the commit history with git log with custom formats for more information on less terminal real estate

imports

Fri, 28 Jan 2022 00:00:00 +0000

On startup, jshell imports a bunch of Java packages by default. Imported packages can be listed with

compile, install, remove

Wed, 19 Jan 2022 00:00:00 +0000

how to compile and install a new kernel and how to remove unused kernels

checking command type

Tue, 18 Jan 2022 00:00:00 +0000

types of shell commands

There are four types of shell commands:

shell builtin – commands, that are built into the shell. and are more often than not shell builtins. Note, that a command can be available as a shell builtin and as an executable or shell script (see next type). An example on my system is the command .
compiled executable / shell script – compiled and installed programs. I.e., programs in and compiled programs installed in or somewhere in.
Scripts, that are executed in a shell or an interpreter like Perl, which is available in most Linux systems in .
shell alias – aliases for commands that are defined in .
shell function – shell functions that are sourced (read) in .

checking command type with type

To check the type of a command, run , i.e. . The following section lists the output of for the four types of shell commands listed above.

functions

Tue, 18 Jan 2022 00:00:00 +0000

how to work with functions – or what is sold to you as functions in shell programming

schemas

Sat, 08 Jan 2022 00:38:48 +0900

making databases more manageable and more comprehensible with schemas

Linux on UEFI platforms

Sun, 23 Nov 2025 00:00:00 +0000

Various information on working with UEFI in Linux, i.e., access to UEFI firmware variables, security considerations for accessing UEFI firmware variables, UEFI features in Linux, etc..

methods, classes and interfaces

Fri, 28 Jan 2022 00:00:00 +0000

Inside methods, classes and interfaces, statements have to end with a semicolon

conditionals

Tue, 18 Jan 2022 00:00:00 +0000

general form of test expressions, i.e. for loops and if statements

internet portal of the PES

Sun, 18 Nov 2018 00:00:00 +0000

I supported the team at Silpion, Hamburg, in developing the internet portal for the PES (Party of European Socialists). Based on an open source CMS in Java, we developed both the public area and the internal area for PES employees to create content and plan and execute events.

Linux userspace tools for UEFI firmware

Sun, 23 Nov 2025 00:00:00 +0000

Information on some Linux userspace tools for working with UEFI firmware, i.e. how to register a Linux kernel with the UEFI firmware boot manager, reading and manipulating UEFI firmware variables, building an UKI, etc..

git branch operations

Wed, 22 Jun 2022 00:00:00 +0000

basic operations

create a branch –
checkout a branch –
list local branches –
list remote branches –
list local and remote branches –
delete a local branch –
delete a remote branch –

create and checkout a branch in one go

git checkout -b <new branch>

connecting local branches to upstream

git push -u origin new-branch

is shorthand for

working with the classpath

Fri, 28 Jan 2022 00:00:00 +0000

In order to be able to access classes in libs or class files that are not part of the JDK, the classpath must be set

loops

Tue, 18 Jan 2022 00:00:00 +0000

In Bash shell programming you can use the usual suspects for loop structures: the for loop, which is usually used to

script files

Sat, 08 Jan 2022 00:38:48 +0900

using script files for automatic creation and preseeding of databases

views

Mon, 24 Apr 2017 18:36:24 +0200

just a quick example of how to generate a view from three tables

building an Unified Kernel Image with dracut

Wed, 14 Jan 2026 00:00:00 +0000

The dracut man page describes dracut as a ’low-level tool for generating an initramfs/initrd image’, but with ‘uefi=yes’ in dracut’s config, dracut builds an UEFI image that is executable by an UEFI firmware. This is perfect for building an Unified Kernel Image.

Java 8

Thu, 13 Oct 2022 00:00:00 +0000

general availability on 2014-03-18

The original schedule aimed to ship the release in early September 2013, but due to an increased focus on browser-related security issues that date was not achievable.

modules

Fri, 28 Jan 2022 00:00:00 +0000

In order to be able to access modules that are not part of the JDK, the module path must be set according to the

Java 9

Fri, 07 Oct 2022 00:00:00 +0000

general availability on 2017-09-22

JEPs

Java 9 comes with a vast list of features. There are 91 JEPs listed in the features and schedule page for JDK 9 (see also JDK 9 ) .

exception handling

Fri, 28 Jan 2022 00:00:00 +0000

If a snippet throws an exception, jshell prints the exception together with the snippet id that caused the exception

tab completion

Fri, 28 Jan 2022 00:00:00 +0000

Tab completion works for commands, command parameters, variables, methods, classes and interfaces

trapping signals

Tue, 18 Jan 2022 00:00:00 +0000

how to trap signals that are sent to your shell script and how to handle them properly

UEFI glossary

Wed, 07 Jan 2026 00:00:00 +0000

Terms used in the domain of UEFI and related domains, and their abbreviation

custom label files

Fri, 29 Aug 2025 00:00:00 +0000

Label files with labels to categorize issues/tickets go into .

Gitea 1.19 introduced a pretty cool new label format. There is an example of a label file on the gitea GitHub page Advanced.yaml . At the time of writing the YAML example misses the three mandatory dashes ‘—’, that indicate the start of a new YAML document.

Java 10

Sat, 16 Jul 2022 00:00:00 +0000

general availability on 2018-03-20

JEPs

new features

JEP	state	summary /remark
JEP 286: Local-Variable Type Inference	standard	enhance the Java Language to extend type inference to declarations of local variables with initializers.
JEP 314: Additional Unicode Language-Tag Extensions	standard	enhance java.util.Locale and related APIs to implement additional Unicode extensions of BCP 47 language tags.
JEP 316: Heap Allocation on Alternative Memory Devices	standard	Enable the HotSpot VM to allocate the Java object heap on an alternative memory device, such as an NV-DIMM, specified by the user.
JEP 317: Experimental Java-Based JIT Compiler	standard	can be enabled with -XX:+UnlockExperimentalVMOptions -XX:+UseJVMCICompiler
JEP 319: Root Certificates	standard	the cacerts keystore in a fresh installation of the JDK was previously empty. It now contains certs from various Root CAs such as DigiCert, Let’s encrypt and Trustwave.
JEP 322: Time-Based Release Versioning	standard	revise the version-string scheme of the Java SE Platform and the JDK, and related versioning information, for present and future time-based release models.

JDK internal

JEP	summary /remark
JEP 296: Consolidate the JDK Forest into a Single Repository	the numerous repositories of the JDK forest are combined into a single repository.
JEP 304: Garbage Collector Interface	improve the source code isolation of different garbage collectors by introducing a clean garbage collector (GC) interface. This is not meant to add or remove a GC.
JEP 307: Parallel Full GC for G1	improve G1 worst-case latencies by making the full GC parallel. G1 is the default GC since Java 9
JEP 310: Application Class-Data Sharing	to improve startup and footprint, extend the existing Class-Data Sharing (“CDS”) feature to allow application classes to be placed in the shared archive.
JEP 312: Thread-Local Handshakes	will help the VM achieve lower latency by reducing the number of global safepoints.

deprecated

none

feedback modes

Fri, 28 Jan 2022 00:00:00 +0000

available feedback modes

JShell comes with four built-in feedback modes, listed in the table below

screen and cursor control

Wed, 19 Jan 2022 00:00:00 +0000

controlling cursor position, text attributes and screen display with tput

Java 11

Sat, 16 Jul 2022 00:00:00 +0000

general availability on 2018-09-25

JEPs

new features

JEP	state	summary /remark
JEP 181: Nest-Based Access Control	standard	introduce nests, an access-control context that aligns with the existing notion of nested types in the Java programming language. Nests allow classes that are logically part of the same code entity, but which are compiled to distinct class files, to access each other’s private members without the need for compilers to insert accessibility-broadening bridge methods.
JEP 309: Dynamic Class-File Constants	standard	extend the Java class-file format to support a new constant-pool form, CONSTANT_Dynamic.
JEP 318: Epsilon	experimental	a GC that handles memory allocation but does not implement any actual memory reclamation mechanism. Once the available Java heap is exhausted, the JVM will shut down.
JEP 321: HTTP Client	standard	standardize the incubated HTTP Client API introduced in JDK 9, via JEP 110, and updated in JDK 10.
JEP 323: Local-Variable Syntax for Lambda Parameters	standard	I prefer the implicitly typed lambda expressions as in Java SE 8 :)
JEP 324: Key Agreement with Curve25519 and Curve448	standard	more efficient and secure than the elliptic curve Diffie-Hellman (ECDH) scheme
JEP 327: Unicode 10	standard	Java SE 10 implements Unicode 8.0
JEP 328: Flight Recorder	standard	records events originating from applications, the JVM and the OS with an performance overhead of under 1%. intended for monitoring, profiling and troubleshooting of apps in production
JEP 329: ChaCha20 and Poly1305 Cryptographic	standard	ChaCha20 is a relatively new stream cipher that can replace the older, insecure RC4 stream cipher.
JEP 330: Launch Single-File Source-Code Programs	standard	you can now launch single file Java apps with a shebang
JEP 331: Low-Overhead Heap Profiling	standard	low-overhead way of sampling Java heap allocations, accessible via JVMTI.
JEP 332: Transport Layer Security (TLS) 1.3	standard	implement version 1.3 of the Transport Layer Security (TLS) Protocol RFC 8446.
JEP 333: ZGC, A Scalable Low-Latency Garbage Collector (Experimental)	experimental	the Z Garbage Collector, also known as ZGC, is a scalable low-latency garbage collector.

JDK internal

JEP	summary /remark
JEP 315: Improve Aarch64 Intrinsics	specialized CPU architecture-specific code patterns improve the performance of user applications and benchmarks.

deprecated

JEP	summary /remark
JEP 335: Deprecate the Nashorn JavaScript Engine	the nashorn engine is a complete implementation of the ECMAScript-262 5.1 standard. With the rapid pace at which ECMAScript language evolves, there’s not enough dev power to maintain Nashorn. Might get resurrected if there are enough devs to maintain a complete implementation of the ECMAScript standard.
JEP 336: Deprecate the Pack200 Tools and API	Pack200 is a compression scheme for JAR files, introduced in Java SE 5.0. Its file format is tightly coupled to the class file format and the JAR file format. Pack200 has been used especially to compress the JDK up to version 8 and applets. Applets are gone and Java 9 and later versions do not rely on Pack200.

removed

JEP	summary /remark
JEP 320: Remove the Java EE and CORBA Modules	From the JEP: “There is no significant interest in developing modern applications with CORBA in Java.”. Yep, CORBA sucked from the time of its inception.

some feature details

JEP 318: Epsilon: A No-Op Garbage Collector (Experimental)

A no-op GC is useful in the following scenarios:

script files

Fri, 28 Jan 2022 00:00:00 +0000

A jshell script file is a sequence of jshell commands and/or snippets, one command or snippet per line

reading files

Tue, 18 Jan 2022 00:00:00 +0000

working with file descriptors and reading files in a shell script with the read command

archiving git repos

Wed, 25 Oct 2023 00:00:00 +0000

There are three ways for creating an archive from a git repo: , , and plain tarballs. Spoiler: as long as you want to archive the local repo in its current state –that is with uncommitted changes– making a tarball from a git repo is not only the most simple way to create an archive from a git repo, but also the best one.

Java 12

Sat, 16 Jul 2022 00:00:00 +0000

general availability on 2019-03-19

JEPs

new features

JEP	state	summary /remark
JEP 189: Shenandoah, A Low-Pause-Time Garbage Collector (Experimental)	experimental	a GC which reduces GC pause times by doing evacuation work concurrently with the running Java threads. Pause times are independent of heap size, the goal is to never interrupt the running program for more than a handful of milliseconds.
JEP 325: Switch Expressions (Preview)	preview	extended switch statement that can be used as either a statement or an expression. Both forms can use either a “traditional” or “simplified” scoping and control flow behavior.
JEP 334: JVM Constants API	standard	an API to model nominal descriptions of key class-file and run-time artifacts, in particular constants that are loadable from the constant pool.
JEP 344: Abortable Mixed Collections for G1	standard	make all pauses in G1 abortable.
JEP 346: Promptly Return Unused Committed Memory from G1	standard	make G1 detect phases of Java heap under-utilization (“idle” phases), and automatically reduce the JVMs heap usage during that time. Tests with a prototype were quite impressive (see blow).

JDK internal

JEP	summary /remark
JEP 230: Microbenchmark Suite	a basic suite of microbenchmarks in the JDK source code. Makes it easy for developers to run existing microbenchmarks and create new ones.
JEP 340: One AArch64 Port, Not Two	remove all of the sources related to the arm64 port while retaining the 32-bit ARM port and the 64-bit aarch64 port.
JEP 341: Default CDS Archives	enhance the JDK build process to generate a class data-sharing (CDS) archive, using the default class list, on 64-bit platforms.

deprecated

none

configuration

Fri, 28 Jan 2022 00:00:00 +0000

the jshell configuration file

On Linux systems, the startup configuration is written to the file .
Windows and Mac OS users will find the file in the corresponding directory inside their home directory / user directory.

locking

Tue, 18 Jan 2022 00:00:00 +0000

locking with homegrown solutions and the command dotlockfile

java 13

Sat, 16 Jul 2022 00:00:00 +0000

general availability on 2019-09-17

jeps

new features

jep	state	summary /remark
jep 351: zgc, uncommit unused memory (Experimental)	experimental	zgc does not currently uncommit and return memory to the operating system, even when that memory has been unused for a long time. enhance zgc to return unused heap memory to the operating system.
jep 354: switch expressions (Second Preview)	second preview	extended switch statement that can be used as either a statement or an expression. both forms can use either a “traditional” or “simplified” scoping and control flow behavior. see comments on ‘JEP 325: Switch Expressions (Preview)’
jep 355: text blocks (Preview)	preview	add text blocks to the java language. a text block is a multi-line string literal that avoids the need for most escape sequences, automatically formats the string in a predictable way, and gives the developer control over format when desired.

jdk internal

jep	summary /remark
jep 350: dynamic cds archives	extend application class-data sharing to allow the dynamic archiving of classes at the end of java application execution. the archived classes will include all loaded application classes and library classes that are not present in the default, base-layer cds archive.
jep 353: reimplement the legacy socket api	replace the underlying implementation used by the java.net.socket and java.net.serversocket apis with a simpler and more modern implementation that is easy to maintain and debug.

deprecated

none

reference

Fri, 28 Jan 2022 00:00:00 +0000

some of the information presented in this series JShell guide stems from the following references:

deprecated syntax

Tue, 18 Jan 2022 00:00:00 +0000

Expressions like <expr> are still prevalent in the wild. If you work with shell script code that uses this deprecated code

Java 14

Sat, 16 Jul 2022 00:00:00 +0000

general availability on 2020-03-17

JEPs

new features

JEP	state	summary /remark
JEP 305: Pattern Matching for instanceof (Preview)	preview	instanceof now saves you from explicit, verbose casts.
JEP 343: Packaging Tool (Incubator)	incubator	create a tool for packaging self-contained Java applications, supporting native packaging formats to give end users a natural installation experience.
JEP 349: JFR Event Streaming	standard	expose JDK Flight Recorder data for continuous monitoring.
JEP 352: Non-Volatile Mapped Byte Buffers	standard	add new JDK-specific file mapping modes so that the FileChannel API can be used to create MappedByteBuffer instances that refer to non-volatile memory. With NVM, it is possible to create and update program state across program runs without the significant translation costs that persistent media normally imply.
JEP 358: Helpful NullPointerExceptions	standard	NPE messages are now more specific about the cause than just listing the line number of the code where the unlucky consumer is.
JEP 359: Records (Preview)	preview	a new kind of restricted class for data containers without boiler code.
JEP 361: Switch Expressions	standard	extended switch statement that can be used as either a statement or an expression. both forms can use either a “traditional” or “simplified” scoping and control flow behavior. see comments on ‘JEP 325: Switch Expressions (Preview)’
JEP 364: ZGC on macOS (Experimental)	experimental	macOS port of the ZGC garbage collector.
JEP 365: ZGC on Windows (Experimental)	experimental	Windows port of the ZGC garbage collector.
JEP 368: Text Blocks (Second Preview)	second preview	add text blocks to the java language. a text block is a multi-line string literal that avoids the need for most escape sequences, automatically formats the string in a predictable way, and gives the developer control over format when desired. see comments on ‘JEP 355: Text Blocks (Preview)’
JEP 370: Foreign-Memory Access API (Incubator)	incubator	an API to allow Java programs to safely and efficiently access foreign memory outside of the Java heap. Applications include sharing memory across multiple processes, and serialization / deserialization of memory content by mapping files into memory (via, e.g., mmap).

JDK internal

JEP	summary /remark
JEP 345: NUMA-Aware Memory Allocation for G1	improves G1 performance on large machines by implementing NUMA-aware memory allocation.

deprecated

JEP	summary /remark
JEP 362: Deprecate the Solaris and SPARC Ports	deprecate the Solaris/SPARC, Solaris/x64, and Linux/SPARC ports, with the intent to remove them in a future release.
JEP 366: Deprecate the ParallelScavenge + SerialOld GC Combination	deprecate the combination of the Parallel Scavenge and Serial Old garbage collection algorithms. It is not a goal to remove this GC combination.

removed

JEP	summary /remark
JEP 363: Remove the Concurrent Mark Sweep (CMS) Garbage Collector	remove the Concurrent Mark Sweep (CMS) garbage collector.
JEP 367: Remove the Pack200 Tools and API	remove the pack200 and unpack200 tools, and the Pack200 API in the java.util.jar package. These tools and API were deprecated for removal in Java SE 11 with the express intent to remove them in a future release.

some feature details

JEP 305: Pattern Matching for instanceof (Preview)

You can now save the explicit cast after an test with code like this:

testing

Tue, 18 Jan 2022 00:00:00 +0000

shellcheck

Check shell scripts with ‘shellcheck’

print out executed expression

Test shell scripts with the ‘-x’ switch:

Java 15

Sat, 16 Jul 2022 00:00:00 +0000

general availability on 202-09-15

JEPs

new features

JEP	state	summary /remark
JEP 339: Edwards-Curve Digital Signature Algorithm (EdDSA)	standard	EdDSA has a better performance than the existing ECDSA implementation (which uses native C code) at the same security strength. This new signature scheme does not replace ECDSA.
JEP 360: Sealed Classes (Preview)	preview	allows the author of a class to specify which classes may extend the class. This allows for more fine grained control of inheritance hierarchies.
JEP 371: Hidden Classes	standard	hidden classes are classes that cannot be used directly by the bytecode of other classes. Hidden classes are intended for use by frameworks that generate classes at run time and use them indirectly, via reflection.
JEP 375: Pattern Matching for instanceof (Second Preview)	second preview	instanceof now saves you from explicit, verbose casts. see comments on ‘JEP 305: Pattern Matching for instanceof (Preview)’
JEP 377: ZGC, A Scalable Low-Latency Garbage Collector	production	the Z Garbage Collector changes from an experimental feature into a product feature. see comments on ‘JEP 333: ZGC: A Scalable Low-Latency Garbage Collector (Experimental)’
JEP 378: Text Blocks	standard	see comments on ‘JEP 355: Text Blocks (Preview)’
JEP 379: Shenandoah	production	a GC which reduces GC pause times by doing evacuation work concurrently with the running Java threads. Pause times are independent of heap size, the goal is to never interrupt the running program for more than a handful of milliseconds. see comments on ‘JEP 189: Shenandoah, A Low-Pause-Time Garbage Collector (Experimental)’
JEP 383: Foreign-Memory Access API (Second Incubator)	incubator	an API to allow Java programs to safely and efficiently access foreign memory outside of the Java heap. Applications include sharing memory across multiple processes, and serialization / deserialization of memory content by mapping files into memory (via, e.g., mmap).
JEP 384: Records (Second Preview)	preview	a new kind of restricted class for data containers without boiler code. see comments on ‘JEP 359: Records (Preview)’

JDK internal

JEP	summary /remark
JEP 373: Reimplement the Legacy DatagramSocket API	From JEP 373, Motivation: “The code base of the java.net.DatagramSocket and java.net.MulticastSocket APIs, and their underlying implementations, is old and brittle.”

deprecated

JEP	summary /remark
JEP 374: Deprecate and Disable Biased Locking	disable biased locking by default, and deprecate all related command-line options.
JEP 385: Deprecate RMI Activation for Removal	deprecate the RMI Activation mechanism for future removal. RMI Activation is an obsolete part of RMI that has been optional since Java 8. No other part of RMI will be deprecated.

removed

JEP	summary /remark
JEP 372: Remove the Nashorn JavaScript Engine	remove the Nashorn JavaScript script engine and APIs, and the jjs tool. The engine, the APIs, and the tool were deprecated for removal in Java 11.
JEP 381: Remove the Solaris and SPARC Ports	remove the source code and build support for the Solaris/SPARC, Solaris/x64, and Linux/SPARC ports. These ports were deprecated for removal in JDK 14.

some feature details

JEP 360: Sealed Classes (Preview)

The motivation behind sealed classes is to provide a more fine grained control of which classes may be permitted to extend a class. Traditional approaches to control class inheritance include:

Java 16

Wed, 20 Jul 2022 00:00:00 +0000

general availability on 2021-03-16

JEPs

new features

JEP	state	summary /remark
JEP 338: Vector API (Incubator)	incubator	provide an initial iteration of an incubator module, jdk.incubator.vector, to express vector computations that reliably compile at runtime to optimal vector hardware instructions on supported CPU architectures and thus achieve superior performance to equivalent scalar computations.
JEP 380: Unix-Domain Socket Channels	standard	add Unix-domain (AF_UNIX) socket support to the socket channel and server-socket channel APIs in the java.nio.channels package. Extend the inherited channel mechanism to support Unix-domain socket channels and server socket channels.
JEP 386: Alpine Linux Port	standard	port the JDK to Alpine Linux, and to other Linux distributions that use musl as their primary C library, on both the x64 and AArch64 architectures.
JEP 388: Windows/AArch64 Port	standard	port the JDK to Windows/AArch64. The focus of this JEP is not the porting effort itself, which is mostly complete, but rather the integration of the port into the JDK main-line repository.
JEP 389: Foreign Linker API	incubator	introduce an API that offers statically-typed, pure-Java access to native code. This API, together with the Foreign-Memory API (JEP 393), will considerably simplify the otherwise error-prone process of binding to a native library.
JEP 390: Warnings for Value-Based Classes	standard	designate the primitive wrapper classes as value-based and deprecate their constructors for removal, prompting new deprecation warnings. Provide warnings about improper attempts to synchronize on instances of any value-based classes in the Java Platform.
JEP 392: Packaging Tool	standard	Provide the jpackage tool, for packaging self-contained Java applications
JEP 393: Foreign-Memory Access API	third incubator	an API to allow Java programs to safely and efficiently access foreign memory outside of the Java heap. Applications include sharing memory across multiple processes, and serialization / deserialization of memory content by mapping files into memory (via, e.g., mmap).
JEP 394: Pattern Matching for instanceof	standard	instanceof now saves you from explicit, verbose casts. see comments on ‘JEP 305: Pattern Matching for instanceof (Preview)’
JEP 395: Records	standard	a new kind of restricted class for data containers without boiler code. see comments on ‘JEP 359: Records (Preview)’
JEP 396: Strongly Encapsulate JDK Internals by Default	standard	Code successfully compiled with earlier releases that directly accesses internal APIs of the JDK will no longer work by default. The strong encapsulation, which has been the default since JDK 9 can be relaxed with the JVM option –illegal-access. The sun.misc package will still be exported by the jdk.unsupported module, and will still be accessible via reflection. Hacking open private fields and protected or private methods of exported java.* APIs by reflection will result in an java.lang.reflect.InaccessibleObjectException.
JEP 397: Sealed Classes	second preview	allows the author of a class to specify which classes may extend the class. This allows for more fine grained control of inheritance hierarchies. see comments on ‘JEP 360: Sealed Classes (Preview)’

JDK internal

JEP	summary /remark
JEP 347: Enable C++14 Language Features	formally allow C++ source code changes within the JDK to take advantage of C++14 language features, and to give specific guidance about which of those features may be used in HotSpot code.
JEP 357: Migrate from Mercurial to Git	migrate the OpenJDK Community’s source code repositories from Mercurial (hg) to Git.
JEP 376: ZGC	move ZGC thread-stack processing from safepoints to a concurrent phase.
JEP 387: Elastic Metaspace	return unused HotSpot class-metadata (i.e., metaspace) memory to the operating system more promptly, reduce metaspace footprint, and simplify the metaspace code in order to reduce maintenance costs.

deprecated

none

Java 17

Tue, 04 Oct 2022 00:00:00 +0000

general availability on 2021-09-14

JEPs

new features

JEP	state	summary /remark
JEP 306: Restore Always-Strict Floating-Point Semantics	standard	make floating-point operations consistently strict, rather than have both strict floating-point semantics (strictfp) and subtly different default floating-point semantics. This will restore the original floating-point semantics to the language and VM, matching the semantics before the introduction of strict and default floating-point modes in Java SE 1.2.
JEP 356: Enhanced Pseudo-Random Number Generators	standard	the new interface RandomGenerator supplies a uniform API for all existing and new PRNGs. RandomGenerators provide methods named ints, longs, doubles, nextBoolean, nextInt, nextLong, nextDouble, and nextFloat, with all their current parameter variations.
JEP 403: Strongly Encapsulate JDK Internals	standard	Code successfully compiled with earlier releases that directly accesses internal APIs of the JDK will no longer work by default. The strong encapsulation, which has been the default since JDK 9 can be relaxed with the JVM option –illegal-access. The sun.misc package will still be exported by the jdk.unsupported module, and will still be accessible via reflection. Hacking open private fields and protected or private methods of exported java.* APIs by reflection will result in an java.lang.reflect.InaccessibleObjectException. see comment on JEP 396: Strongly Encapsulate JDK Internals by Default.
JEP 406: Pattern Matching for switch	preview	introduces pattern matching for switch expressions and statements, along with extensions to the language of patterns.
JEP 409: Sealed Classes	standard	allows the author of a class to specify which classes may extend the class. This allows for more fine grained control of inheritance hierarchies. See comments on JEP 360: Sealed Classes (Preview).
JEP 412: Foreign Function & Memory API	incubator	eases the acces for devs to code and data on the same machine as the JVM but outside of the JVM, without the drawbacks of JNI.
JEP 414: Vector API	second incubator	provides a second iteration of an incubator module, jdk.incubator.vector, to express vector computations that reliably compile at runtime to optimal vector hardware instructions on supported CPU architectures and thus achieve superior performance to equivalent scalar computations.
JEP 415: Context-Specific Deserialization Filters	standard	allows applications to configure context-specific and dynamically-selected deserialization filters via a JVM-wide filter factory that is invoked to select a filter for each individual deserialization operation. This JEP addresses some drawbacks of the deserialization filters introduced in Java 9 with JEP 290: Filter Incoming Serialization Data .

JDK internal

JEP	summary /remark
JEP 382: New macOS Rendering Pipeline	implement a Java 2D internal rendering pipeline for macOS using the Apple Metal API as alternative to the existing pipeline, which uses the deprecated Apple OpenGL API.
JEP 391: macOS/AArch64 Port	port the JDK to macOS/AArch64. Apple has announced a long-term plan to transition their line of Macintosh computers from x64 to AArch64.

deprecated

JEP	summary /remark
JEP 398: Deprecate the Applet API for Removal	deprecate the Applet API for removal. The Applet API was previously deprecated, though not for removal, by JEP 289: Deprecate the Applet API in Java 9.
JEP 411: Deprecate the Security Manager for Removal	deprecates the Security Manager for removal in a future release. The Security Manager dates from Java 1.0. It has not been the primary means of securing client-side Java code for many years, and it has rarely been used to secure server-side code.

removed

JEP	summary /remark
JEP 407: Remove RMI Activation	removes the Remote Method Invocation (RMI) Activation mechanism, while preserving the rest of RMI. The Jakarta Activation (JavaBeans Activation Framework / JAF in Java EE) is completely unrelated to the Java SE Remote Method Invocation (RMI) Activation and thus not affected by the removal.
JEP 410: Remove the Experimental AOT and JIT Compiler	remove the experimental Java-based ahead-of-time (AOT) and just-in-time (JIT) compiler. This compiler has seen little use since its introduction and the effort required to maintain it is significant. Devs who want to use the Graal compiler for either AOT or JIT compilation can use the Graal VM

some feature details

JEP 356: Enhanced Pseudo-Random Number Generators

Four new specialized random generator interfaces that extend RandomGenerator are provided:

Java 18

Thu, 06 Oct 2022 00:00:00 +0000

general availability on 2022-03-22

JEPs

new features

JEP	state	summary /remark
JEP 400: UTF-8 by Default	standard	specifies UTF-8 as the default charset of the standard Java APIs. APIs that depend upon the default charset will behave consistently across all implementations, operating systems, locales, and configurations.
JEP 408: Simple Web Server	standard	provides a command-line tool to start a minimal web server that serves static files only (no CGI or servlet-like functionality) for prototyping, ad-hoc coding, and testing purposes, particularly in educational contexts.
JEP 413: Code Snippets in Java API Documentation	standard	introduces an @snippet tag for JavaDoc’s Standard Doclet, to simplify the inclusion of example source code in API documentation.
JEP 417: Vector API	third incubator	provide a third iteration of an incubator module, jdk.incubator.vector, to express vector computations that reliably compile at runtime to optimal vector hardware instructions on supported CPU architectures and thus achieve superior performance to equivalent scalar computations.
JEP 418: Internet-Address Resolution SPI	standard	define a service-provider interface (SPI) for host name and address resolution, so that java.net.InetAddress can make use of resolvers other than the platform’s built-in resolver.
JEP 419: Foreign Function & Memory API	second incubator	eases the acces for devs to code and data on the same machine as the JVM but outside of the JVM, without the drawbacks of JNI.
JEP 420: Pattern Matching for switch	second preview	introduces pattern matching for switch expressions and statements, along with extensions to the language of patterns. See comments on JEP 406: Pattern Matching for switch (Preview).

JDK internal

JEP	summary /remark
JEP 416: Reimplement Core Reflection with Method Handles	reimplement java.lang.reflect.Method, Constructor, and Field on top of java.lang.invoke method handles. Making method handles the underlying mechanism for reflection will reduce the maintenance and development cost of both the java.lang.reflect and java.lang.invoke APIs.

deprecated

JEP	summary /remark
JEP 421: Deprecate Finalization for Removal	deprecate finalization for removal in a future release. Finalization remains enabled by default for now, but can be disabled to facilitate early testing. In a future release it will be disabled by default, and in a later release it will be removed. Note that finalization is distinct from both the finally block of the try-finally construct. No changes are proposed to try-finally.

removed

none

Java 19

Thu, 06 Oct 2022 00:00:00 +0000

general availability on 20 September 2022

JEPs

new features

JEP	state	summary /remark
JEP 405: Record Patterns	preview	introduces record patterns to deconstruct record values. Record patterns and type patterns can be nested to for a declarative and composable form of data navigation and processing.
JEP 422: Linux/RISC-V Port	standard	port the JDK to Linux/RISC-V.
JEP 424: Foreign Function & Memory API	preview	eases the access for devs to code and data on the same machine as the JVM but outside of the JVM, without the drawbacks of JNI.
JEP 425: Virtual Threads	preview	introduces lightweight threads called virtual threads to the Java platform.
JEP 426: Vector API	fourth incubator	provides a second iteration of an incubator module, jdk.incubator.vector, to express vector computations that reliably compile at runtime to optimal vector hardware instructions on supported CPU architectures and thus achieve superior performance to equivalent scalar computations.
JEP 427: Pattern Matching for switch	third preview	introduces pattern matching for switch expressions and statements, along with extensions to the language of patterns. See comments on JEP 406: Pattern Matching for switch (Preview).
JEP 428: Structured Concurrency	incubator	simplifies multithreaded programming by introducing an API for structured concurrency. Structured concurrency treats multiple tasks running in different threads as a single unit of work, thereby streamlining error handling and cancellation, improving reliability, and enhancing observability.

JDK internal

none

importing repos into Gitea

Fri, 29 Aug 2025 00:00:00 +0000

Repos that have been created outside gitea can be imported, or in Gitea speak adopted, and managed by Gitea. I’m using both terms import and adopt here.

issues and fixes

Fri, 29 Aug 2025 00:00:00 +0000

starting gitea with another user than defined in gitea.conf

results in:

... routers/init.go:74:mustInitCtx() [F] code.gitea.io/gitea/modules/git.InitFull(ctx) failed: failed to set git global config diff.algorithm, err: exit status 255 - warning: unable to access '/home/rudolf/.config/git/gitconfig': Permission denied error: could not lock config file /home/rudolf/.config/git/gitconfig: Permission denied - warning: unable to access '/home/rudolf/.config/git/gitconfig': Permission denied error: could not lock config file /home/rudolf/.config/git/gitconfig: Permission denied

the fix is to run before running gitea.

installing your own Root CA certificate

Wed, 20 Aug 2025 00:00:00 +0000

Before you can install your own Root CA Certificate you need to set up your own CA (Certificate Authority).

frontmatter

Sat, 13 Jun 2026 00:00:00 +0000

quoting in dynamic values

It’s a bit counterintuitive, but the following works, no escaping of the double quotes is required:

how to asses a hype

Wed, 15 Jul 2026 00:00:00 +0000

The genAI hype is crashing against reality. The profits that the use of genAI have been promised have not materialized. No near-total white-collar jobs wipe-out happened, as some doomsday fortune-teller predicted. Companies re-hire call center agents they fired a while ago. Seems that genAI chatbots wasn’t such a good bet. Codebases are more bug-ridden than ever. Using genAI trained on bananaware (the product matures at the customer’s site) wasn’t such a terrible good idea, neither. I’m still waiting for those butt-ugly genAI images disappearing from blog posts and websites, like some of the 90’ties worst style crimes on the web did.

Stop Targeting Junior Devs

Thu, 04 Jun 2026 00:00:00 +0000

The recurring theme of the disappearing developer … Now it’s the undergraduate students and junior devs who are getting targeted. From low-code, no-code, ADF to outsourcing, from time to time crops up some “innovative” way to replace lots if not almost all of those pesky devs that take just too much time to churn out the stuff we want from them. Didn’t work out so well each and every time. It won’t work this time either.

Endlich: ein xDD zum aktuellen Hype um LLMs

Fri, 22 May 2026 00:00:00 +0000

BDD, MDD, TDD und andere DDs haben mir und den Teams, mit denen ich gute Software bauen konnte, nicht besonders viel gebracht oder wurden gar nicht erst eingesetzt. Domain Driven Design nehme ich hier raus, dazu gleich mehr.

a quick vi survival guide

Wed, 20 May 2026 00:00:00 +0000

This is for when you get stuck with an abomination of an editor called vi. No sophisticated vi-foo here, this is just the basics that get you covered for simple editing of files.

CI/CD server landscape in 2026

Mon, 11 May 2026 00:00:00 +0000

It’s been a while since I have checked what is going on in the development of CI/CD servers. I’ve worked extensively with Bamboo and TeamCity, and have a fair amount of exposure to GitLab and GitHub. Time for a quick survey.

why I don't use AI tools for coding or writing in general

Thu, 16 Oct 2025 00:00:00 +0000

If I tell people that I don’t to use AI tools for coding or my site, I see incredulous looks and get remarks from which I conclude that people see me in the backwards camp. I use the following rule that has proven itself in science, when I evaluate new tools and techniques: the more outrageous the claim, the more convincing the arguments for supporting it must be. Some simple tests should prove the claim or at least make the tool or technique look very promising.

some notes on installing Gitea

Wed, 27 Aug 2025 00:00:00 +0000

I’ve been running a heavily outdated version of Gitea. Rather than doing an update on it, I just reinstalled it.

why I'd never work with Jenkins

Sat, 04 Feb 2023 00:00:00 +0000

Another day, another project turned down, because they use Jenkins for CI/CD (the requirements were that I actually would have had to work with that piece of crap).

damned ... 404

Sun, 26 Jun 2022 00:00:00 +0000