Java classpath program files x86

PATH and CLASSPATH

This section explains how to use the PATH and CLASSPATH environment variables on Microsoft Windows, Solaris, and Linux. Consult the installation instructions included with your installation of the Java Development Kit (JDK) software bundle for current information.

After installing the software, the JDK directory will have the structure shown below.

The bin directory contains both the compiler and the launcher.

Update the PATH Environment Variable (Microsoft Windows)

You can run Java applications just fine without setting the PATH environment variable. Or, you can optionally set it as a convenience.

Set the PATH environment variable if you want to be able to conveniently run the executables ( javac.exe , java.exe , javadoc.exe , and so on) from any directory without having to type the full path of the command. If you do not set the PATH variable, you need to specify the full path to the executable every time you run it, such as:

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

The PATH environment variable is a series of directories separated by semicolons ( ; ). Microsoft Windows looks for programs in the PATH directories in order, from left to right. You should have only one bin directory for the JDK in the path at a time (those following the first are ignored), so if one is already present, you can update that particular entry.

The following is an example of a PATH environment variable:

C:\Java\jdk1.7.0\bin;C:\Windows\System32\;C:\Windows\;C:\Windows\System32\Wbem

It is useful to set the PATH environment variable permanently so it will persist after rebooting. To make a permanent change to the PATH variable, use the System icon in the Control Panel. The precise procedure varies depending on the version of Windows:

1. Select Start, select Control Panel. double click System, and select the Advanced tab.
2. Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New .
3. In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

1. From the desktop, right click the My Computer icon.
2. Choose Properties from the context menu.
3. Click the Advanced tab (Advanced system settings link in Vista).
4. Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New .
5. In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

1. From the desktop, right click the Computer icon.
2. Choose Properties from the context menu.
3. Click the Advanced system settings link.
4. Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New .
5. In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

Note: You may see a PATH environment variable similar to the following when editing it from the Control Panel:

%JAVA_HOME%\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem

Variables enclosed in percentage signs ( % ) are existing environment variables. If one of these variables is listed in the Environment Variables window from the Control Panel (such as JAVA_HOME ), then you can edit its value. If it does not appear, then it is a special environment variable that the operating system has defined. For example, SystemRoot is the location of the Microsoft Windows system folder. To obtain the value of a environment variable, enter the following at a command prompt. (This example obtains the value of the SystemRoot environment variable):

Update the PATH Variable (Solaris and Linux)

You can run the JDK just fine without setting the PATH variable, or you can optionally set it as a convenience. However, you should set the path variable if you want to be able to run the executables ( javac , java , javadoc , and so on) from any directory without having to type the full path of the command. If you do not set the PATH variable, you need to specify the full path to the executable every time you run it, such as:

% /usr/local/jdk1.7.0/bin/javac MyClass.java

To find out if the path is properly set, execute:

This will print the version of the java tool, if it can find it. If the version is old or you get the error java: Command not found, then the path is not properly set.

To set the path permanently, set the path in your startup file.

For C shell ( csh ), edit the startup file (~/.cshrc ):

set path=(/usr/local/jdk1.7.0/bin $path)

For bash , edit the startup file ( ~/.bashrc ):

PATH=/usr/local/jdk1.7.0/bin:$PATH export PATH

For ksh , the startup file is named by the environment variable, ENV . To set the path:

PATH=/usr/local/jdk1.7.0/bin:$PATH export PATH

For sh , edit the profile file ( ~/.profile ):

PATH=/usr/local/jdk1.7.0/bin:$PATH export PATH

Then load the startup file and verify that the path is set by repeating the java command:

% source ~/.cshrc % java -version

Checking the CLASSPATH variable (All platforms)

The CLASSPATH variable is one way to tell applications, including the JDK tools, where to look for user classes. (Classes that are part of the JRE, JDK platform, and extensions should be defined through other means, such as the bootstrap class path or the extensions directory.)

The preferred way to specify the class path is by using the -cp command line switch. This allows the CLASSPATH to be set individually for each application without affecting other applications. Setting the CLASSPATH can be tricky and should be performed with care.

The default value of the class path is «.», meaning that only the current directory is searched. Specifying either the CLASSPATH variable or the -cp command line switch overrides this value.

To check whether CLASSPATH is set on Microsoft Windows NT/2000/XP, execute the following:

On Solaris or Linux, execute the following:

If CLASSPATH is not set you will get a CLASSPATH: Undefined variable error (Solaris or Linux) or simply %CLASSPATH% (Microsoft Windows NT/2000/XP).

To modify the CLASSPATH , use the same procedure you used for the PATH variable.

Class path wildcards allow you to include an entire directory of .jar files in the class path without explicitly naming them individually. For more information, including an explanation of class path wildcards, and a detailed description on how to clean up the CLASSPATH environment variable, see the Setting the Class Path technical note.

Previous page: Miscellaneous Methods in System
Next page: Questions and Exercises: The Platform Environment

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How to Set Classpath for Java in Windows

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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