shell.nix: Development shell with dependencies installed

.gitignore

@@ -1,5 +1,8 @@
+/.idea
+
 # Ignore Gradle project-specific cache directory
-.gradle
+/.gradle
 
 # Ignore Gradle build output directory
-build
+/build
+/app/build

.idea/compiler.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CompilerConfiguration">
-    <bytecodeTargetLevel target="17" />
+    <bytecodeTargetLevel target="23" />
   </component>
-</project>
+</project>

.idea/gradle.xml

@@ -4,8 +4,10 @@
   <component name="GradleSettings">
     <option name="linkedExternalProjectsSettings">
       <GradleProjectSettings>
+        <option name="distributionType" value="LOCAL" />
         <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="gradleJvm" value="#JAVA_HOME" />
+        <option name="gradleHome" value="/usr/lib/gradle" />
+        <option name="gradleJvm" value="usr-lib-jdk" />
         <option name="modules">
           <set>
             <option value="$PROJECT_DIR$" />
@@ -15,4 +17,4 @@
       </GradleProjectSettings>
     </option>
   </component>
-</project>
+</project>

.idea/misc.xml

@@ -1,8 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
-  <component name="ExternalStorageConfigurationManager" enabled="true" />
   <component name="FrameworkDetectionExcludesConfiguration">
     <file type="web" url="file://$PROJECT_DIR$" />
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="jbr-17" project-jdk-type="JavaSDK" />
-</project>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_X" project-jdk-name="jbr-17" project-jdk-type="JavaSDK" />
+</project>

README.md

@@ -4,13 +4,17 @@
 
 ### Setup
 
-Check which Java toolchains can be found by Gradle:
+Dependencies (JDK23, Gradle, IntelliJ) can be installed by running `nix-shell`.
+
+**Commandline**
+
+Check which Java toolchains Gradle finds:
 
 ```shell
 ./gradlew javaToolchains
 ```
 
-This should include version >= 17, e.g.:
+This should include version >= 23, e.g.:
 
 ```
  + N/A JDK 23-ga
@@ -22,6 +26,17 @@ This should include version >= 17, e.g.:
      | Detected by:        Current JVM
 ```
 
+**IntelliJ**
+
+When using `nix-shell`, some configuration is necessary:
+
+- STRG ALT SHIFT s -> SDK -> add JDK ->
+    - home path: /usr/lib/openjdk
+    - name: usr-lib-jdk
+- STRG ALT s -> build tools -> gradle ->
+    - local installation: /usr/lib/gradle
+    - Gradle JVM: usr-lib-jdk
+
 ### Tasks
 
 List all Gradle tasks which can be run:

app/build.gradle.kts

@@ -28,7 +28,7 @@ dependencies {
 // Apply a specific Java toolchain to ease working on different environments.
 java {
     toolchain {
-        languageVersion = JavaLanguageVersion.of(17)
+        languageVersion = JavaLanguageVersion.of(23)
     }
 }
 

shell.nix

@@ -0,0 +1,27 @@
+# Gradle's toolchain support does not work with IntelliJ, thus we have to use buildFHSUserEnv
+
+# https://discourse.nixos.org/t/how-to-create-a-development-environment-with-intellij-idea-and-openjdk/10153
+{
+  pkgs ? import <nixpkgs> {
+     # https://github.com/NixOS/nixpkgs/issues/166220#issuecomment-1745803058
+     config.allowUnfree = true;
+  }
+}:
+
+let
+  unstable = import (fetchTarball https://github.com/NixOS/nixpkgs/archive/nixos-unstable.tar.gz) { };
+  jdk = unstable.jdk23;
+  gradle = unstable.gradle;
+in
+
+(
+  pkgs.buildFHSUserEnv
+  {
+    name = "intellij-gradle-jdk23";
+    targetPkgs = pkgs_: [
+      pkgs_.jetbrains.idea-ultimate
+      jdk
+      gradle
+    ];
+  }
+).env