Java: Difference between revisions

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__TOC__

== Java Web Start ==

Available as <code>javaws</code> in package <code>adoptopenjdk-icedtea-web</code>.

== JDK options ==

Your default choice should probably be to install <code>~~jdk11~~</code>, which is an alias ~~for <code>openjdk11<~~/~~code>~~. If you're in a server environment, go for <code>~~jdk11_headless~~</code>. Java 11 is the currently-maintained LTS version of OpenJDK as of ~~Oct 2019~~.

Your default choice should probably be to install <code>jdk</code>, which is an alias to the latest [https://en.wikipedia.org/wiki/Long-term_support LTS]. If you're in a server environment, go for <code>jdk21_headless</code>. Java 21 is the currently-maintained LTS version of OpenJDK as of April 2024.

As you might expect, though, many flavors of Java are available in NixOS.

* OpenJDK, by far the most popular non-Oracle JVM implementation

** <code>~~openjdk8~~[_headless]</code> for a legacy Java 8 VM required by some older apps

** <code>jdk8[_headless]</code> for a legacy Java 8 VM required by some older apps

** <code>~~openjdk11~~[_headless]</code>, the currently-supported LTS version of OpenJDK

** <code>jdk21[_headless]</code>, the currently-supported LTS version of OpenJDK

** <code>~~openjdk12~~[_headless]</code>, the current version of OpenJDK

** <code>jdk22[_headless]</code>, the current version of OpenJDK

* AdoptOpenJDK, prebuilt binaries for OpenJDK

* Temurin, formerly AdoptOpenJDK, prebuilt binaries for OpenJDK

** <code>~~adoptopenjdk~~-bin</code> points to the latest version of ~~AdoptOpenJDK~~, which is version 11 at the time of writing.

** <code>temurin-bin</code> points to the latest version of Temurin, which is version 21 at the time of writing.

** <code>~~adoptopenjdk~~-jre-bin</code> is available if you want to avoid downloading the compiler and only require the runtime environment.

** <code>temurin-jre-bin</code> is available if you want to avoid downloading the compiler and only require the runtime environment.

* JetBrains JDK (<code>jetbrains.jdk</code>), a fork of OpenJDK with modifications made by JetBrains

* Oracle's JDK (<code>oraclejdk</code>), only version 8 is available.

== VSCode + Language Support for Java (TM) by Red Hat extension ==

Unfortunately the extension contains and uses a version of the JRE which makes use of dynamically loaded libraries, which nix cannot accomodate out-of-the-box. Fortunately there's a simple solution in the use of [https://github.com/Mic92/nix-ld nix-ld]. Here's a simple <code>flake.nix</code> snippet to get you started (I'll focus on the <code>devShell</code> part for brevity):

# flake.nix

devShell = pkgs.mkShell {

buildInputs = [

pkgs.gradle

pkgs.jdk17

];

NIX_LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath [

pkgs.stdenv.cc.cc

pkgs.openssl

];

NIX_LD = pkgs.lib.fileContents "${pkgs.stdenv.cc}/nix-support/dynamic-linker";

# ^--- when using direnv, this line will require the 'use flake --impure' option.

};

</syntaxhighlight>

The important lines above are the two starting with <code>NIX_LD...</code>. They will let nix-ld wrap the required, dynamically loaded libraries so that they are found when building the <code>devShell</code>.

Another solution is to use the <code>[https://github.com/redhat-developer/vscode-java?tab=readme-ov-file#supported-vs-code-settings java.jdt.ls.java.home]</code> VSCode setting to point to a nix-built Java 17. For example, using home-manager's settings: <syntaxhighlight lang="nix">

programs.vscode.enable = true;

programs.vscode.extensions = [ pkgs.vscode-extensions.redhat.java ];

programs.vscode.userSettings = {

"java.jdt.ls.java.home" = "${pkgs.jdk17}";

};

</syntaxhighlight>Note that this will still result in the extension downloading its own JRE, it just will not be used.

== Using Oracle JDK instead of Open JDK ==

Almost all Java packages in nixpkgs use Open JDK in form of a '''jre''' dependency. If you use Oracle JDK and also want other applications to use it, you can simply tweak your <code>.nixpkgs/config.nix</code> so that your desired application uses Oracles JDK or JRE.

Almost all Java packages in nixpkgs use Open JDK in form of a '''jre''' dependency. If you use Oracle JDK and also want other applications to use it, you can simply tweak your <code>nixpkgs/config.nix</code> so that your desired application uses Oracles JDK or JRE.

Example with UMLet with JRE

Line 35:

Line 70:

To install the Oracle JRE system-wide, you need to explicitly accept the license in addition to allowing unfree modules:

# /etc/nixos/configuration.nix

Line 43:

Line 79:

</syntaxhighlight>

Working with `requireFile` (manual downloading the tarballs and manual adding in to the nix store) might be annoying and nixops-unfriendly, so it can be ~~overrides~~ in overlays

Working with <code>requireFile</code> (manual downloading the tarballs and manual adding in to the nix store) might be annoying and nixops-unfriendly, so it can be overridden in overlays

let

nixpkgs.overlays = let

files = {

"jdk-8u241-linux-linux-arm32-vfp-hflt.tar.gz" = /home/user/blobs/java/jdk-8u241-linux-linux-arm32-vfp-hflt.tar.gz;

Line 53:

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"jdk-8u241-linux-x64.tar.gz" = /home/user/blobs/java/jdk-8u241-linux-x64.tar.gz;

};

in

in [

~~nixpkgs.overlays =~~ [

(self: super: {

requireFile = args @ {name, url, sha1 ? null, sha256 ? null}:

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inherit name;

outputHashMode = "flat";

outputHashAlgo = if sha256 == null then "sha256" else "sha1";

outputHashAlgo = if sha256 != null then "sha256" else "sha1";

outputHash = if sha256 == null then sha256 else sha1 ;

outputHash = if sha256 != null then sha256 else sha1 ;

buildCommand = "cp ${files.${name}} $out";

}

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== Better font rendering==

By default java does not enable ~~antialiasing~~ for font rendering. By exporting environment variables, this can be fixed:

By default java does not enable anti-aliasing for font rendering. By exporting environment variables, this can be fixed:

Line 82:

Line 117:

== Overriding java jks Certificate Store ==

Overriding the java certificate store may be required for adding your own Root certificates in case your company uses an internal PKI or the company utilizes an intercepting proxy.

=== jdk8 ===

Overriding the jdk8 certificate store is possible by overriding the '''cacert''' parameter of the package:

Line 112:

Line 150:

=== jdk11 ===

JDK11 does not provide the cacert overridable and therefore it is not possible to use the same technique to override the truststore.

As an alternative solution you can either set an environment variable, <code>JAVAX_NET_SSL_TRUSTSTORE</code>, or pass an argument to your program, <code>-Djavax.net.ssl.trustStore</code>, with the location of your cacert. See [https://discourse.nixos.org/t/custom-ssl-certificates-for-jdk/18297/9 discussion].

== Building and Packaging ==

See the [https://nixos.org/manual/nixpkgs/#sec-language-java Java section in the Nixpkgs manual].

=== Maven ===

[https://maven.apache.org/run.html Maven] is a build tool for Java. The typical build command is

<pre>mvn verify</pre>

[https://github.com/fzakaria/mvn2nix mvn2nix], [https://nixos.org/manual/nixpkgs/stable/#maven-buildmavenpackage buildMavenPackage] (recommended) can be used to build Maven projects with Nix

See also: [https://fzakaria.com/2020/07/20/packaging-a-maven-application-with-nix.html Packaging a Maven application with Nix] and [https://github.com/NixOS/nixpkgs/blob/master/pkgs/by-name/ma/maven/build-maven-package.nix buildMavenPackage source]

=== Ant ===

[https://ant.apache.org/manual/running.html Ant] is a build tool for Java. To build the <code>compile</code> target, run

<pre>ant compile</pre>

To list available build targets, run

==== Ivy ====

[https://ant.apache.org/ivy/ Ivy] is a package manager for Ant, not to be confused with [https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/interpreters/ivy/default.nix ivy] - an APL-like calculator

To fetch ivy sources manually, see for example [https://github.com/NixOS/nixpkgs/blob/master/pkgs/applications/editors/jedit pkgs/applications/editors/jedit]

To fetch ivy sources in a fixed-output-derivation, see for example [https://github.com/milahu/nur-packages/blob/master/pkgs/yacy/yacy.nix yacy.nix]

== JavaFX and Webkit support ==

To include support for JavaFX and Webkit, use the <code>enableJavaFX</code> and <code>withWebKit</code> options:

{ pkgs, ... }:

let

jdkWithFX = pkgs.openjdk.override {

enableJavaFX = true; # for JavaFX

# include following line if JavaFX with Webkit is needed

openjfx_jdk = pkgs.openjfx.override { withWebKit = true; };

};

in

...

</syntaxHighlight>

== Further reading ==

{{Nixpkgs manual|sec-language-java}} {{Wikipedia|Java_(programming_language)}}

[[Category:Languages]]

@@ Line 2: / Line 2: @@
 __TOC__
+== Java Web Start ==
+Available as <code>javaws</code> in package <code>adoptopenjdk-icedtea-web</code>.
 == JDK options ==
-Your default choice should probably be to install <code>jdk11</code>, which is an alias for <code>openjdk11</code>. If you're in a server environment, go for <code>jdk11_headless</code>. Java 11 is the currently-maintained LTS version of OpenJDK as of Oct 2019.
+Your default choice should probably be to install <code>jdk</code>, which is an alias to the latest [https://en.wikipedia.org/wiki/Long-term_support LTS]. If you're in a server environment, go for <code>jdk21_headless</code>. Java 21 is the currently-maintained LTS version of OpenJDK as of April 2024.
 As you might expect, though, many flavors of Java are available in NixOS.
 * OpenJDK, by far the most popular non-Oracle JVM implementation
-** <code>openjdk8[_headless]</code> for a legacy Java 8 VM required by some older apps
+** <code>jdk8[_headless]</code> for a legacy Java 8 VM required by some older apps
-** <code>openjdk11[_headless]</code>, the currently-supported LTS version of OpenJDK
+** <code>jdk21[_headless]</code>, the currently-supported LTS version of OpenJDK
-** <code>openjdk12[_headless]</code>, the current version of OpenJDK
+** <code>jdk22[_headless]</code>, the current version of OpenJDK
-* AdoptOpenJDK, prebuilt binaries for OpenJDK
+* Temurin, formerly AdoptOpenJDK, prebuilt binaries for OpenJDK
-** <code>adoptopenjdk-bin</code> points to the latest version of AdoptOpenJDK, which is version 11 at the time of writing.
+** <code>temurin-bin</code> points to the latest version of Temurin, which is version 21 at the time of writing.
-** <code>adoptopenjdk-jre-bin</code> is available if you want to avoid downloading the compiler and only require the runtime environment.
+** <code>temurin-jre-bin</code> is available if you want to avoid downloading the compiler and only require the runtime environment.
 * JetBrains JDK (<code>jetbrains.jdk</code>), a fork of OpenJDK with modifications made by JetBrains
 * Oracle's JDK (<code>oraclejdk</code>), only version 8 is available.
+== VSCode + Language Support for Java (TM) by Red Hat extension ==
+Unfortunately the extension contains and uses a version of the JRE which makes use of dynamically loaded libraries, which nix cannot accomodate out-of-the-box. Fortunately there's a simple solution in the use of [https://github.com/Mic92/nix-ld nix-ld]. Here's a simple <code>flake.nix</code> snippet to get you started (I'll focus on the <code>devShell</code> part for brevity):
+<syntaxhighlight lang="nix" line highlight="6,10" copy>
+# flake.nix
+devShell = pkgs.mkShell {
+  buildInputs = [
+    pkgs.gradle
+    pkgs.jdk17
+  ];
+  NIX_LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath [
+    pkgs.stdenv.cc.cc
+    pkgs.openssl
+  ];
+  NIX_LD = pkgs.lib.fileContents "${pkgs.stdenv.cc}/nix-support/dynamic-linker";
+  # ^--- when using direnv, this line will require the 'use flake --impure' option.
+};
+</syntaxhighlight>
+The important lines above are the two starting with <code>NIX_LD...</code>. They will let nix-ld wrap the required, dynamically loaded libraries so that they are found when building the <code>devShell</code>.
+Another solution is to use the <code>[https://github.com/redhat-developer/vscode-java?tab=readme-ov-file#supported-vs-code-settings java.jdt.ls.java.home]</code> VSCode setting to point to a nix-built Java 17. For example, using home-manager's settings: <syntaxhighlight lang="nix">
+programs.vscode.enable = true;
+programs.vscode.extensions = [ pkgs.vscode-extensions.redhat.java ];
+programs.vscode.userSettings = {
+  "java.jdt.ls.java.home" = "${pkgs.jdk17}";
+};
+</syntaxhighlight>Note that this will still result in the extension downloading its own JRE, it just will not be used.
 == Using Oracle JDK instead of Open JDK ==
-Almost all Java packages in nixpkgs use Open JDK in form of a '''jre''' dependency. If you use Oracle JDK and also want other applications to use it, you can simply tweak your <code>.nixpkgs/config.nix</code> so that your desired application uses Oracles JDK or JRE.
+Almost all Java packages in nixpkgs use Open JDK in form of a '''jre''' dependency. If you use Oracle JDK and also want other applications to use it, you can simply tweak your <code>nixpkgs/config.nix</code> so that your desired application uses Oracles JDK or JRE.
 Example with UMLet with JRE
@@ Line 35: / Line 70: @@
 To install the Oracle JRE system-wide, you need to explicitly accept the license in addition to allowing unfree modules:
 <syntaxhighlight lang="nix">
 # /etc/nixos/configuration.nix
@@ Line 43: / Line 79: @@
 </syntaxhighlight>
-Working with `requireFile` (manual downloading the tarballs and manual adding in to the nix store) might be annoying and nixops-unfriendly, so it can be overrides in overlays
+Working with <code>requireFile</code> (manual downloading the tarballs and manual adding in to the nix store) might be annoying and nixops-unfriendly, so it can be overridden in overlays
 <syntaxhighlight lang="nix">
-let
+nixpkgs.overlays = let
    files = {
      "jdk-8u241-linux-linux-arm32-vfp-hflt.tar.gz" = /home/user/blobs/java/jdk-8u241-linux-linux-arm32-vfp-hflt.tar.gz;
@@ Line 53: / Line 89: @@
      "jdk-8u241-linux-x64.tar.gz"                  = /home/user/blobs/java/jdk-8u241-linux-x64.tar.gz;
    };
-in
+in [
-nixpkgs.overlays = [
    (self: super: {
      requireFile = args @ {name, url, sha1 ? null, sha256 ? null}:
@@ Line 61: / Line 96: @@
            inherit name;
            outputHashMode = "flat";
-           outputHashAlgo = if sha256 == null then "sha256" else "sha1";
+           outputHashAlgo = if sha256 != null then "sha256" else "sha1";
-           outputHash     = if sha256 == null then  sha256  else  sha1 ;
+           outputHash     = if sha256 != null then  sha256  else  sha1 ;
            buildCommand   = "cp ${files.${name}} $out";
          }
@@ Line 73: / Line 108: @@
 == Better font rendering==
-By default java does not enable antialiasing for font rendering. By exporting environment variables, this can be fixed:
+By default java does not enable anti-aliasing for font rendering. By exporting environment variables, this can be fixed:
 <syntaxhighlight lang="console">
@@ Line 82: / Line 117: @@
 == Overriding java jks Certificate Store ==
 Overriding the java certificate store may be required for adding your own Root certificates in case your company uses an internal PKI or the company utilizes an intercepting proxy.
 === jdk8 ===
 Overriding the jdk8 certificate store is possible by overriding the '''cacert''' parameter of the package:
@@ Line 112: / Line 150: @@
 === jdk11 ===
-JDK11 does not provide the cacert overridable and therefore it is not possible to use the same technique to override the truststore.
+JDK11 does not provide the cacert overridable and therefore it is not possible to use the same technique to override the truststore.
+As an alternative solution you can either set an environment variable, <code>JAVAX_NET_SSL_TRUSTSTORE</code>, or pass an argument to your program, <code>-Djavax.net.ssl.trustStore</code>, with the location of your cacert. See [https://discourse.nixos.org/t/custom-ssl-certificates-for-jdk/18297/9 discussion].
+== Building and Packaging ==
+See the [https://nixos.org/manual/nixpkgs/#sec-language-java Java section in the Nixpkgs manual].
+=== Maven ===
+[https://maven.apache.org/run.html Maven] is a build tool for Java. The typical build command is
+<pre>mvn verify</pre>
+[https://github.com/fzakaria/mvn2nix mvn2nix], [https://nixos.org/manual/nixpkgs/stable/#maven-buildmavenpackage buildMavenPackage] (recommended) can be used to build Maven projects with Nix
+See also: [https://fzakaria.com/2020/07/20/packaging-a-maven-application-with-nix.html Packaging a Maven application with Nix] and [https://github.com/NixOS/nixpkgs/blob/master/pkgs/by-name/ma/maven/build-maven-package.nix buildMavenPackage source]
+=== Ant ===
+[https://ant.apache.org/manual/running.html Ant] is a build tool for Java. To build the <code>compile</code> target, run
+<pre>ant compile</pre>
+To list available build targets, run
+<pre>ant -p</pre>
+==== Ivy ====
+[https://ant.apache.org/ivy/ Ivy] is a package manager for Ant, not to be confused with [https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/interpreters/ivy/default.nix ivy] - an APL-like calculator
+To fetch ivy sources manually, see for example [https://github.com/NixOS/nixpkgs/blob/master/pkgs/applications/editors/jedit pkgs/applications/editors/jedit]
+To fetch ivy sources in a fixed-output-derivation, see for example [https://github.com/milahu/nur-packages/blob/master/pkgs/yacy/yacy.nix yacy.nix]
+== JavaFX and Webkit support ==
+To include support for JavaFX and Webkit, use the <code>enableJavaFX</code> and <code>withWebKit</code> options:
+<syntaxHighlight lang=nix>
+{ pkgs, ... }:
+let
+  jdkWithFX = pkgs.openjdk.override {
+    enableJavaFX = true; # for JavaFX
+    # include following line if JavaFX with Webkit is needed
+    openjfx_jdk = pkgs.openjfx.override { withWebKit = true; };
+  };
+in
+...
+</syntaxHighlight>
+== Further reading ==
+{{Nixpkgs manual|sec-language-java}}<br /><br /><br /><br /><br />{{Wikipedia|Java_(programming_language)}}
+[[Category:Languages]]