How to set and override classpath for Java ?

Setting Classpath

CLASSPATH is an environment variable which is used by JVM to locate user defined classes.

To set classpath, specify value of environment variable CLASSPATH.

CLASSPATH variable is not case sensitive.

So, Classpath == CLASSPATH == classpath

Set in Windows

1. Right click on My computer - properties - Advanced - Environment variable.

2. Provide environment variable :

    Name : CLASSPATH

    Value : JAVA_HOME\lib;.

* include current directory by adding semicolon and dot sign

Check

Type in console :

echo %CLASSPATH%

Set in Unix / Linux

Put this line in either your .bash_profile or .bashrc script which will run on login in Linux / Unix Machine : export CLASSPATH="JAVA_HOME/lib:."

* include current directory by adding colon and dot sign

Check

echo ${CLASSPATH}

Overriding Classpath while running programs

To override Java classpath defined by environment variable CLASSPATH , 

provide option "-cp" or "-classpath" while running your program

Example

CLASSPATH= /home/tester/classes

java -cp $CLASSPATH Test