Devops Monk

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

# List available Java 8 builds
sdk list java | grep "8\."

# Install Amazon Corretto 8
sdk install java 8.422.05.1-amzn

# Install Eclipse Temurin 8
sdk install java 8.0.412-tem

# Set as default
sdk default java 8.422.05.1-amzn

# Verify
java -version
# openjdk version "1.8.0_422"
# OpenJDK Runtime Environment Corretto-8.422.05.1 (build 1.8.0_422-b05)

brew tap homebrew/cask-versions
brew install --cask temurin8

# Amazon Corretto 8
wget -O - https://apt.corretto.aws/corretto.key | sudo gpg --dearmor -o /usr/share/keyrings/corretto-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/corretto-keyring.gpg] https://apt.corretto.aws stable main" | sudo tee /etc/apt/sources.list.d/amazon-corretto.list
sudo apt-get update
sudo apt-get install -y java-8-amazon-corretto-jdk

# Eclipse Temurin 8
sudo apt-get install -y temurin-8-jdk

[System.Environment]::SetEnvironmentVariable("JAVA_HOME", "C:\Program Files\Eclipse Adoptium\jdk-8.0.412.8-hotspot", "Machine")

java -version
# openjdk version "1.8.0_422"

javac -version
# javac 1.8.0_422

echo $JAVA_HOME
# /Users/abhay/.sdkman/candidates/java/8.422.05.1-amzn

<properties>
    <maven.compiler.source>8</maven.compiler.source>
    <maven.compiler.target>8</maven.compiler.target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.13.0</version>
            <configuration>
                <source>8</source>
                <target>8</target>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>
    </plugins>
</build>

mvn wrapper:wrapper -Dmaven=3.9.6

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.junit</groupId>
            <artifactId>junit-bom</artifactId>
            <version>5.10.3</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

plugins {
    id 'java'
}

java {
    sourceCompatibility = JavaVersion.VERSION_1_8
    targetCompatibility = JavaVersion.VERSION_1_8
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation platform('org.junit:junit-bom:5.10.3')
    testImplementation 'org.junit.jupiter:junit-jupiter'
}

test {
    useJUnitPlatform()
}

plugins {
    java
}

java {
    sourceCompatibility = JavaVersion.VERSION_1_8
    targetCompatibility = JavaVersion.VERSION_1_8
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation(platform("org.junit:junit-bom:5.10.3"))
    testImplementation("org.junit.jupiter:junit-jupiter")
}

tasks.test {
    useJUnitPlatform()
}

gradle wrapper --gradle-version 8.7

{
    "java.jdt.ls.java.home": "/path/to/jdk8",
    "java.configuration.runtimes": [
        {
            "name": "JavaSE-1.8",
            "path": "/path/to/jdk8",
            "default": true
        }
    ],
    "java.compile.nullAnalysis.mode": "automatic"
}

# macOS with SDKMAN
echo $JAVA_HOME

# macOS with Homebrew
/usr/libexec/java_home -v 1.8

import java.util.*;
import java.util.stream.*;
import java.util.function.*;
import java.time.*;

public class Java8Test {
    public static void main(String[] args) {
        // Lambdas + Streams
        List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "Dave");
        names.stream()
            .filter(s -> s.length() > 3)
            .map(String::toUpperCase)
            .sorted()
            .forEach(System.out::println);

        // Optional
        Optional<String> opt = names.stream()
            .filter(s -> s.startsWith("C"))
            .findFirst();
        System.out.println(opt.orElse("none"));

        // Date/Time API
        LocalDate today = LocalDate.now();
        System.out.println("Today: " + today);

        // Default method
        List<Integer> nums = new ArrayList<>(Arrays.asList(3, 1, 4, 1, 5));
        nums.sort(Comparator.naturalOrder());
        System.out.println(nums);

        // Method reference
        Function<String, Integer> len = String::length;
        System.out.println(len.apply("hello"));
    }
}

javac Java8Test.java && java Java8Test

# Check what java is being used
which java
java -version

# SDKMAN: switch version
sdk use java 8.422.05.1-amzn

# Without SDKMAN: update JAVA_HOME manually
export JAVA_HOME=$(/usr/libexec/java_home -v 1.8)  # macOS