Difference between PATH and CLASSPATH

Are you confused between path and classpath in java?

Give this article a read, it will surely clear all your confusions

What is PATH?

• PATH is an environment variable used by our Operating System to locate different files, like executable files (.exe) or java binaries ( java or javac command).
• .path is like, we are setting an environment for the operating system, to look in this path for executables.

What is CLASSPATH?

• CLASSPATH is also an environment variable, which is used by the java compiler, to find the path of classes i.e. when we talk about Java Enterprise Edition (J2EE)? we define the path of JAR files.

The main difference between PATH and CLASSPATH is that Path is set for java tools in java programs like java and javac, which are used to compile your code. Whereas CLASSPATH? is used by System or Application class loader to locate and load compile Java bytecodes stored in the .class file.

Rt.jar file contains all classes and the bin folder contains all tools, so we set PATH up to bin folder and set CLASSPATH up to lib folder, as shown in the above picture.

Difference between path and classpath on various parameters:-

1 . Definition?

• PATH

? - It is used by the operating system to locate executable files (.exe) and java binaries.

• CLASSPATH

- It is used by the application class loader to load the .class files(compiled java codes).

2. Setting

• PATH

- To set PATH in Java, you need to include the JDK_HOME/bin directory in the PATH environment variable.

• CLASSPATH

- To set CLASSPATH in Java you need to include all those directories where you have put either your .class file or JAR file which is required by your Java application.

3. Overridden

• PATH

- Path once set cannot be overridden by java settings.

- Once you install Java on your machine, it is necessary to set the PATH environment variable so that executables (javac.exe,java.exe,javadoc.exe) run smoothly from any directory without needing to type the entire path.

Example:-

? When the path variable is set

?????C:\javac Test.java

When path variable is not set

C:\Java\jdk1.7.0\bin\javac Test.java

• CLASSPATH

- Classpath values can be overridden by using the command-line option -cp or -classpath to both java and javac commands.

- Java compiler and JVM use CLASSPATH to determine the location of required class files.

Example:-

C:\Program Files\Java\jdk1.6.0\bin

4 . Usage

• PATH

-PATH is used by the operating systems (Windows and Linux) to execute commands in the shell or to find any binary.

• CLASSPATH

-CLASSPATH is used by Application CLASSLOADER to load class files

How to set PATH and CLASSPATH in Windows and Unix

Both PATH and CLASSPATH are environment variables and they can be set using

• export command in Linux
• set keyword in DOS and Windows

Command to set PATH in Windows

set PATH=%PATH%;C:\Program Files\Java\JDK1.6.20\bin

Command to set PATH in UNIX/Linux

export PATH = ${PATH}:/opt/Java/JDK1.6.18/bin

Command to set CLASSPATH in windows

set CLASSPATH=%CLASSPATH%;C:\Program Files\Java\JDK1.6.20\lib

Command to set CLASSPATH in Unix/Linux

export CLASSPATH= ${CLASSPATH}:/opt/Java/JDK1.6.18/lib

Thank you, Hope this article would have helped you. Suggestions are welcome.