How do we set the Java environment variable in cmd.exe?

When you install Java in your system first of all you need to set the environment variables which are path and class path.

• PATH− The path environment variable is used to specify the set of directories which contains executional programs.

  When you try to execute a program from command line, the operating system searches for the specified program in the current directly, if available, executes it.

  In case the programs are not available in the current directory, operating system verifies in the set of directories specified in the ‘PATH’ environment variable.

  You need to set path for compiler (javac.exe) and JVM(java.exe),which exists in the bin folder of the JDK.

• CLASSPATH − The class path environment variable is used to specify the location of the classes and packages.

  When we try to import classes and packages other that those that are available with Java Standard Library.

  JVM verifies the current directly for them, if not available it verifies the set of directories specified in the ‘CLASSPATH’ environment variable.

  The rt.jar file in the lib folder of JRE contains all the basic packages for Java therefore, you need to set classpath for this folder.

Setting environment variable from the command prompt

To set path −

• Open command prompt.
• Copy the location of the javac and java commands i.e. bin folder of JDK example: C:\Program Files\Java\jdk1.8.0_101\bin
• Using the SET command set the path variable in the command prompt as −

SET PATH=C:\Program Files\Java\jdk_version\bin

To set classpath −

• Open command prompt.
• Copy the location of the rt.jar file i.e. lib folder of JDK example: C:\Program Files\Java\jdk1.8.0_101\lib
• Using the SET command set the classpath variable in the command prompt as −

SET CLASSPATH= C:\Program Files\Java\jdk1.8.0_101\lib