Merge pull request #105230 from Mic92/java-doc

doc/java: convert to markdown

3 files changed, 92 insertions, 78 deletions

diff --git a/doc/languages-frameworks/index.xml b/doc/languages-frameworks/index.xml
index 65fb2e877f7..c302b67cfd5 100644
--- a/doc/languages-frameworks/index.xml
+++ b/doc/languages-frameworks/index.xml
@@ -17,7 +17,7 @@
  <xi:include href="haskell.section.xml" />
  <xi:include href="idris.section.xml" />
  <xi:include href="ios.section.xml" />
- <xi:include href="java.xml" />
+ <xi:include href="java.section.xml" />
  <xi:include href="lua.section.xml" />
  <xi:include href="maven.section.xml" />
  <xi:include href="node.section.xml" />
diff --git a/doc/languages-frameworks/java.section.md b/doc/languages-frameworks/java.section.md
new file mode 100644
index 00000000000..77919d43f74
--- /dev/null
+++ b/doc/languages-frameworks/java.section.md
@@ -0,0 +1,91 @@
+# Java {#sec-language-java}
+
+Ant-based Java packages are typically built from source as follows:
+
+```nix
+stdenv.mkDerivation {
+  name = "...";
+  src = fetchurl { ... };
+
+  nativeBuildInputs = [ jdk ant ];
+
+  buildPhase = "ant";
+}
+```
+
+Note that `jdk` is an alias for the OpenJDK (self-built where available,
+or pre-built via Zulu). Platforms with OpenJDK not (yet) in Nixpkgs
+(`Aarch32`, `Aarch64`) point to the (unfree) `oraclejdk`.
+
+JAR files that are intended to be used by other packages should be
+installed in `$out/share/java`. JDKs have a stdenv setup hook that add
+any JARs in the `share/java` directories of the build inputs to the
+`CLASSPATH` environment variable. For instance, if the package `libfoo`
+installs a JAR named `foo.jar` in its `share/java` directory, and
+another package declares the attribute
+
+```nix
+buildInputs = [ libfoo ];
+nativeBuildInputs = [ jdk ];
+```
+
+then `CLASSPATH` will be set to
+`/nix/store/...-libfoo/share/java/foo.jar`.
+
+Private JARs should be installed in a location like
+`$out/share/package-name`.
+
+If your Java package provides a program, you need to generate a wrapper
+script to run it using a JRE. You can use `makeWrapper` for this:
+
+```nix
+nativeBuildInputs = [ makeWrapper ];
+
+installPhase = ''
+  mkdir -p $out/bin
+  makeWrapper ${jre}/bin/java $out/bin/foo \
+    --add-flags "-cp $out/share/java/foo.jar org.foo.Main"
+'';
+```
+
+Since the introduction of the Java Platform Module System in Java 9,
+Java distributions typically no longer ship with a general-purpose JRE:
+instead, they allow generating a JRE with only the modules required for
+your application(s). Because we can't predict what modules will be
+needed on a general-purpose system, the default jre package is the full
+JDK. When building a minimal system/image, you can override the
+`modules` parameter on `jre_minimal` to build a JRE with only the
+modules relevant for you:
+
+```nix
+let
+  my_jre = pkgs.jre_minimal.override {
+    modules = [
+      # The modules used by 'something' and 'other' combined:
+      "java.base"
+      "java.logging"
+    ];
+  };
+  something = (pkgs.something.override { jre = my_jre; });
+  other = (pkgs.other.override { jre = my_jre; });
+in
+  ...
+```
+
+Note all JDKs passthru `home`, so if your application requires
+environment variables like `JAVA_HOME` being set, that can be done in a
+generic fashion with the `--set` argument of `makeWrapper`:
+
+```bash
+--set JAVA_HOME ${jdk.home}
+```
+
+It is possible to use a different Java compiler than `javac` from the
+OpenJDK. For instance, to use the GNU Java Compiler:
+
+```nix
+nativeBuildInputs = [ gcj ant ];
+```
+
+Here, Ant will automatically use `gij` (the GNU Java Runtime) instead of
+the OpenJRE.
diff --git a/doc/languages-frameworks/java.xml b/doc/languages-frameworks/java.xml
deleted file mode 100644
index 881d492b5bf..00000000000
--- a/doc/languages-frameworks/java.xml
+++ /dev/null
@@ -1,77 +0,0 @@
-<section xmlns="http://docbook.org/ns/docbook"
-         xmlns:xlink="http://www.w3.org/1999/xlink"
-         xml:id="sec-language-java">
- <title>Java</title>
-
- <para>
-  Ant-based Java packages are typically built from source as follows:
-<programlisting>
-stdenv.mkDerivation {
-  name = "...";
-  src = fetchurl { ... };
-
-  nativeBuildInputs = [ jdk ant ];
-
-  buildPhase = "ant";
-}
-</programlisting>
-  Note that <varname>jdk</varname> is an alias for the OpenJDK (self-built where available, or pre-built via Zulu). Platforms with OpenJDK not (yet) in Nixpkgs (<literal>Aarch32</literal>, <literal>Aarch64</literal>) point to the (unfree) <literal>oraclejdk</literal>.
- </para>
-
- <para>
-  JAR files that are intended to be used by other packages should be installed in <filename>$out/share/java</filename>. JDKs have a stdenv setup hook that add any JARs in the <filename>share/java</filename> directories of the build inputs to the <envar>CLASSPATH</envar> environment variable. For instance, if the package <literal>libfoo</literal> installs a JAR named <filename>foo.jar</filename> in its <filename>share/java</filename> directory, and another package declares the attribute
-<programlisting>
-buildInputs = [ libfoo ];
-nativeBuildInputs = [ jdk ];
-</programlisting>
-  then <envar>CLASSPATH</envar> will be set to <filename>/nix/store/...-libfoo/share/java/foo.jar</filename>.
- </para>
-
- <para>
-  Private JARs should be installed in a location like <filename>$out/share/<replaceable>package-name</replaceable></filename>.
- </para>
-
- <para>
-  If your Java package provides a program, you need to generate a wrapper script to run it using a JRE. You can use <literal>makeWrapper</literal> for this:
-<programlisting>
-nativeBuildInputs = [ makeWrapper ];
-
-installPhase =
-  ''
-    mkdir -p $out/bin
-    makeWrapper ${jre}/bin/java $out/bin/foo \
-      --add-flags "-cp $out/share/java/foo.jar org.foo.Main"
-  '';
-</programlisting>
-Since the introduction of the Java Platform Module System in Java 9, Java distributions typically no longer ship with a general-purpose JRE: instead, they allow generating a JRE with only the modules required for your application(s). Because we can't predict what modules will be needed on a general-purpose system, the default <package>jre</package> package is the full JDK. When building a minimal system/image, you can override the <literal>modules</literal> parameter on <literal>jre_minimal</literal> to build a JRE with only the modules relevant for you:
-<programlisting>
-let
-  my_jre = pkgs.jre_minimal.override {
-    modules = [
-      # The modules used by 'something' and 'other' combined:
-      "java.base"
-      "java.logging"
-    ];
-  };
-  something = (pkgs.something.override { jre = my_jre; });
-  other = (pkgs.other.override { jre = my_jre; });
-in
-  ...
-</programlisting>
- </para>
-
- <para>
-  Note all JDKs passthru <literal>home</literal>, so if your application requires environment variables like <envar>JAVA_HOME</envar> being set, that can be done in a generic fashion with the <literal>--set</literal> argument of <literal>makeWrapper</literal>:
-<programlisting>
---set JAVA_HOME ${jdk.home}
-</programlisting>
- </para>
-
- <para>
-  It is possible to use a different Java compiler than <command>javac</command> from the OpenJDK. For instance, to use the GNU Java Compiler:
-<programlisting>
-nativeBuildInputs = [ gcj ant ];
-</programlisting>
-  Here, Ant will automatically use <command>gij</command> (the GNU Java Runtime) instead of the OpenJRE.
- </para>
-</section>