You need the JDK (Java Develoment Kit), not just the runtime. It's also sometimes called the SDK (Software..) The runtime is what people use just to run your your programs.

Look here

http://java.sun.com/javase/downloads/index.jsp

You can use the just the JDK to create programs, but it can be difficult for a newbie to get started unless they are savvy about such things. The best option is to download one of the choices that also includes the netbeans IDE. It provides a nice, comfortable environment to program with a minimun of hassle.

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