Java: Software Development Kit

The most popular non-IDE (see IDEs) Java compiler is Sun's Software Development Kit (SDK) (aka the Java Development Kit (JDK)). It's free, and does a good job. The only problem is that the compiler is only a compiler - no editor and no graphical user interface. It must be used from the DOS command line window, or with a program editor (eg, TextPad, jEdit, ...) which have an interface to the compiler to give some of the benefits of an IDE.

Free Download

Download from java.sun.com. There are three editions - get the "standard edition". Sun has major problems getting the names right, so this is still called Java 2 some places altho it is Java 5 in others.

• J2SE - Java 2 Standard Edition - You want this.
• J2ME - Java 2 Micro Edition - This is for phones, PDAs, etc.
• J2EE - Java 2 Enterprise Edition - You don't want this unless you're doing Java client server programming, and even then, you probably don't need it.

Installation

Installing the JDK is easy (at least in Windows).

CLASSPATH

Both the Java compiler (javac) and Java runtime (java) need to know where to find class files. The standard Java packages used in imports are not a problem, but the file system paths of other classes must be specified. The operating system (eg, Windows) maintains environment variables that supply information to the programs on request. The CLASSPATH variable is a semi-colon separated list of directories or jar files to to search in. In addition to non-Sun libraries that are used, the current directory (".") is specified so that classes a user is working on will be found.