Java 8 for Mac OS and writing a Hello World using Lambda


Follow the instruction to download java-8 lambda featured JDK & JRE.

  1. Get the java 8 lambda package

  2. Unzip and put it in some folder that you wanted or preferably at /System/Library/Java/java-8-lambda

  3. Open terminal and set your JAVA_HOME to point to your path and now execute the java & javac commands to see if the libraries are good.

$export JAVA_HOME=/System/Library/Java/java-8-lambda
$java -version
	openjdk version "1.8.0-ea"
	OpenJDK Runtime Environment (build 1.8.0-ea-lambda-nightly-h1171-20120911-b56-b00)
	OpenJDK 64-Bit Server VM (build 24.0-b21, mixed mode)

$javac -version
	javac 1.8.0-ea

If you see the above versions, then you have set the path right and got the libraries working. Write any java 8 lambda program ( click here for sample ) and compile in the same “Terminal” session.

To set the JAVA_HOME permanently, create/open the ~/.bashrc or ~/.bash_profile and set the JAVA_HOME path in it.

Compiling & Running Java 8 program

I’ve considered 3 choices here

  • Using Terminal
  • Using the Eclipse - External Tools features
  • Using Apache Ant - Either in Eclipse or Terminal. I prefer Eclipse for a quick start.

Using Terminal

Whatever you did above, are all is what you need to do to run it in terminal. And preferably have it in a shell script.

Using Eclipse - External Tools

All you have to setup is these two items:

javac

Eclipse external tools setup for javac java-8 lambda
Eclipse external tools setup for javac java-8 lambda

java

Eclipse external tools setup for java java-8 lambda
Eclipse external tools setup for java java-8 lambda

Now run javac and then followed by java.

Using Apache Ant

This is much more customizable and easier to run. Something similar to a Terminal approach, but much nicer.

Here is my an ant script - combines java & javac

<project name="HelloJava8" default="Main" basedir=".">

	<property name="src.dir" location="src" />
	<property name="build.dir" location="bin" />
	<property name="build.compiler" value="modern" />
	<property name="main.class" value="HelloJava8" />

	<!-- set java8 as jre -->
	<path id="build.classpath"></path>

	<!-- Deletes the existing build directory-->
	<target name="clean">
		<delete dir="${build.dir}" />
	</target>

	<!-- Creates the  build  directory-->
	<target name="makedir">
		<mkdir dir="${build.dir}" />
	</target>

	<!-- Compiles the java code -->
	<target name="compile" depends="clean, makedir">
		<javac  srcdir="${src.dir}" destdir="${build.dir}" classpathref="build.classpath" />
	</target>

	<target name="Main" depends="compile">
		<description>Main target</description>
		<java classname="${main.class}" classpath="${classes.dir};${build.dir}" fork="yes"/>
	</target>


</project>

If you are running this in a terminal, create a shell script to export the ANT_HOME variable to the ANT path.

Running Ant in Eclipse

Make sure to update some settings in Eclipse preferences for Ant and configure the .

Eclipse Project Build settings for Java 8 Lambda JRE
ava 8 Lambda JRE - Project Build settings
Configuring JRE for Java 8 Lambda JRE
Java 8 Lambda - Configuring JRE in Eclipse
Ant Configuration for Eclipse
Ant Configuration for Eclipse
JRE - Configuration for Ant for Eclipse
JRE - Configuration for Ant for Eclipse

Hello World

And here is a Hello world using a lambda function to test.

import java.util.Arrays;
import java.util.List;
public class HelloJava8 {

	public static void main(String[] args) {
		System.out.println("Welcome to Java8! First lambda in java");
		List<String> msg = Arrays.asList("So","Nice","that","lambda","works","in", "java");

		msg.forEach( e-> { System.out.println(e); } );

	}

}

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