Classpath in Java refers to the path which will be used by the classloaders to load class in Java. If the classpath is not set correctly you are more likely to get ClassNotFoundException or NoClassDefFoundError exceptions. Classpath can be specified by using CLASSPATH variable in the Environment variable and using -cp or -classpath command line option. In this tutorial we will learn how to set Classpath in Environment variable as well as command line.
Setting classpath for Java in Windows – Environment Variable
In order to set the class for Windows (Windows 7, Windows XP etc) we need to specify the CLASSPATH variable in the Environment Variable, The CLASSPATH variable is not case sensitive. Follow the below steps to set classpath
Set Classpath in Windows XP
- Right click on My Computer and go to properties (or) Press Windows + Pause to open up System Properties. Now traverse to Advanced Tab and click on “Environment Variable”.
- If the classpath already exist in System Variable, then put a semi-colon(;) at the end and add the Path till lib folder eg : “C:\Program Files\Java\jdk1.7.0_75\lib”
- If the classpath doesn’t exist in System Variable, then under System Variable click on New give Variable Name as “CLASSPATH” and Variable Value as “C:\Program Files\Java\jdk1.7.0_75\lib”
- In order to check the classpath which is set, type echo %CLASSPATH% in command prompt, it will display the CLASSPATH which is set.
Set Classpath in Windows 7 or Windows 8
Setting up classpath in Windows 7 or Windows 8 is almost the same as Windows XP with some slight changes.
- Right click on Computer and go to properties (or) Press Windows + Pause to open up System prompt. In that Click on the “Advanced System Settings” to open System Properties.
- Now traverse to Advanced Tab and click on “Environment Variable”.
- If the classpath already exist in System Variable, then put a semi-colon(;) at the end and add the Path till lib folder eg : “C:\Program Files\Java\jdk1.7.0_75\lib”
- If the classpath doesn’t exist in System Variable, then under System Variable click on New give Variable Name as “CLASSPATH” and Variable Value as “C:\Program Files\Java\jdk1.7.0_75\lib”
Add CLASSPATH environment variable via command line
you can set the CLASSPATH using command line using the below command. If there is no CLASSPATH already exist the we can use below command.
SET CLASSPATH=.;C:\Program Files\Java\jdk1.7.0_75\lib
Point to be noted is that we need to have a ‘.;’ before our actual path to denote our current directory. Since JDK 1.3, if no CLASSPATH is set explicitly, the default is set to the current working directory ‘.’. However, if you explicitly set your CLASSPATH, you have to include the current directory ‘.’ explicitly. Otherwise, the current directory will not be searched.
If a CLASSPATH entry already exist then we need to include it along with our path, by running the below command
SET CLASSPATH=%CLASSPATH%;C:\Program Files\Java\jdk1.7.0_75\lib
Setting classpath for Java in Windows – Command Line
In order to set the classpath for Java via Command Line, we will be using the command -classpath or -cp.
If we need to set classpath for a jar and class
java -classpath “Spring.jar” MyClassName
Set classpath for multiple jars in the same directory.
java -classpath .; \*;
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