<chapter 2>2-1-2. Installing the Java SDK

The app Engine SDK for the Java Runtime Environment runs on any computer running the Java SE development tool (JDK). The Java SDK APP engine supports JDK 6, and when running APP engine, the Java Runtime Environment uses the JAVA6 JVM and JRE. (JDK5 support is limited and outdated)

If you don't have it yet, you can download and install the Java 6 JDK for most platforms from Oracle's website. (For Mac users, see the next section):

Http://www.oracle.com/technetwork/java/javase/downloads/index.html

You can test whether the Java Development Kit is installed on your system and check its version by running the following command at the command line.

Javac-version

If you have already installed the Java 6 SDK, this command will print the version number like Javac 1.6.0. The actual output depends on all of your specific versions.

App Engine Java applications use interfaces and features from Java Enterprise Edition (Java EE). The APP Engine SDK contains the implementation of the relevant Java EE features. You do not need a standalone Java EE implementation.

The steps to install the app Engine SDK for Java depend on whether you want to use Google Plugin for the Eclipse IDE. We will discuss these situations separately.

Java on Mac OS X

By default, version 10.8 of Mac OS x (Mountain Lion) or version 10.7 (lion) does not contain the Java 6 runtime environment. If you're running Mac OS X10.8, you'll probably be prompted to download and install Java 6 The first time you run eclipse. If you are running Mac OS X10.7 and you are not updating from the previous major version of this operating system, you will need to download and install Java for OS X Lion from Apple's website:

http://support.apple.com/kb/DL1421

If you are running Mac OS X10.6 (Snow Leopard), or have updated from 10.6 to 10.7, you should have installed JAVA6. You may need to run Apple's software Update from the Apple menu to make sure you have the latest minor version (minor version).

<chapter 2>2-1-2. Installing the Java SDK