Devops Monk

# Install SDKMAN
curl -s "https://get.sdkman.io" | bash
source "$HOME/.sdkman/bin/sdkman-init.sh"

# List available Java 11 distributions
sdk list java | grep "11\."

# Install Eclipse Temurin 11
sdk install java 11.0.22-tem

# Set as default for this project
sdk use java 11.0.22-tem

# Verify
java -version
# openjdk version "11.0.22" 2024-01-16
# OpenJDK Runtime Environment Temurin-11.0.22+7 (build 11.0.22+7)

brew install --cask temurin@11
export JAVA_HOME=$(/usr/libexec/java_home -v 11)
java -version

sudo apt-get update
sudo apt-get install -y temurin-11-jdk
# Or from system packages:
sudo apt-get install -y openjdk-11-jdk

winget install EclipseAdoptium.Temurin.11.JDK

# Set JAVA_HOME
export JAVA_HOME=/path/to/jdk-11
export PATH=$JAVA_HOME/bin:$PATH

# Verify
java -version
javac -version

mvn -version
# Apache Maven 3.9.6

# If older, upgrade via SDKMAN
sdk install maven 3.9.6

<!-- pom.xml -->
<properties>
  <java.version>11</java.version>
  <maven.compiler.source>11</maven.compiler.source>
  <maven.compiler.target>11</maven.compiler.target>
</properties>

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>3.12.1</version>
      <configuration>
        <release>11</release>
        <!-- Use --release instead of source/target — it also sets the bootstrap classpath -->
      </configuration>
    </plugin>
  </plugins>
</build>

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <version>3.12.1</version>
  <configuration>
    <release>11</release>
    <compilerArgs>
      <arg>--enable-preview</arg>
    </compilerArgs>
  </configuration>
</plugin>

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <version>3.2.5</version>
  <configuration>
    <argLine>--enable-preview</argLine>
  </configuration>
</plugin>

<!-- ~/.m2/toolchains.xml -->
<toolchains>
  <toolchain>
    <type>jdk</type>
    <provides>
      <version>11</version>
      <vendor>temurin</vendor>
    </provides>
    <configuration>
      <jdkHome>/path/to/jdk-11</jdkHome>
    </configuration>
  </toolchain>
</toolchains>

<!-- pom.xml -->
<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-toolchains-plugin</artifactId>
  <version>3.1.0</version>
  <executions>
    <execution>
      <goals><goal>toolchain</goal></goals>
    </execution>
  </executions>
  <configuration>
    <toolchains>
      <jdk>
        <version>11</version>
        <vendor>temurin</vendor>
      </jdk>
    </toolchains>
  </configuration>
</plugin>

# Check current version
./gradlew --version

# Upgrade wrapper
./gradlew wrapper --gradle-version=8.7

plugins {
    id 'java'
}

java {
    sourceCompatibility = JavaVersion.VERSION_11
    targetCompatibility = JavaVersion.VERSION_11
    // Alternatively use toolchains (preferred):
}

// Preferred: Java toolchain support (Gradle 6.7+)
java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(11)
        vendor = JvmVendorSpec.ADOPTIUM  // Eclipse Temurin
    }
}

plugins {
    java
}

java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(11))
        vendor.set(JvmVendorSpec.ADOPTIUM)
    }
}

tasks.withType<JavaCompile>().configureEach {
    options.release.set(11)
}

// gradle/wrapper/gradle-wrapper.properties
distributionUrl=https://services.gradle.org/distributions/gradle-8.7-bin.zip

// build.gradle.kts
java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(11))
    }
}
// Gradle will download Temurin 11 automatically if not present

// Install via marketplace or command palette
"vscjava.vscode-java-pack"        // Java Extension Pack (includes Language Support, Debugger, Maven)
"vscjava.vscode-gradle"           // Gradle for Java

// .vscode/settings.json
{
  "java.jdt.ls.java.home": "/path/to/jdk-11",
  "java.configuration.runtimes": [
    {
      "name": "JavaSE-11",
      "path": "/path/to/jdk-11",
      "default": true
    }
  ]
}

// .vscode/settings.json
{
  "java.configuration.updateBuildConfiguration": "automatic",
  "java.compile.nullAnalysis.mode": "automatic"
}

# Compile a simple Java 11 feature to confirm everything works
cat > Test.java << 'EOF'
import java.util.List;
import java.net.http.HttpClient;

public class Test {
    public static void main(String[] args) {
        // var keyword (Java 10)
        var list = List.of("Java", "11");

        // String.isBlank() (Java 11)
        list.stream()
            .filter(s -> !s.isBlank())
            .forEach(System.out::println);

        // HTTP Client (Java 11)
        var client = HttpClient.newHttpClient();
        System.out.println("Setup complete. HttpClient: " + client.version());
    }
}
EOF

javac --release 11 Test.java
java Test
# Java
# 11
# Setup complete. HttpClient: HTTP_2