Java - Classpath variable

Java classes needed to execute a Java program can be physically located in different file system directories. When Java classes are loaded, it searches different file system directories specified in the CLASSPATH variable to resolve references to the classes needed for execution.

The class path can be set using either the:

• -classpath option (shortened -cp) when calling an SDK tool

sdkTool -classpath classpath1;classpath2...

The -classpath option is present in the following sdk (java, jdb, javac, and javah ). Example:

# Windows with ;
java -cp /directory/with/my/class;anotherDirToaJar path/To/MainClass 
# Linux with :
java -cp /directory/with/my/class:anotherDirToaJar path/To/MainClass 

By setting the CLASSPATH environment variable in a command line

C:> set CLASSPATH=classpath1;classpath2... 

in a manifest file

Class-Path: lib/supportLib.jar lib/supportLib2.jar

You need to add the directory root of the class definition.

Example for the class <wrap box>utility.myapp</note> located in the directory <wrap box>c:\java\MyClasses\utility\myapp</note>, you need to add the directory <wrap box>c:\java\MyClasses\</note>

java -classpath C:\java\myClasses utility.myapp.Cool

• Adding one jar

In an archive file (a .zip or .jar file) the class path entry is the path to and including the .zip or .jar file. For example, to use a class library that is in a .jar file, the command would look something like this:

java -classpath C:\java\myClasses\myClasses.jar utility.myapp.Cool

• Adding all JAR files in a directory (since Java 6)

REM Windows
java -classpath ".;c:\mylib\*" MyApp

echo Linux example
java -classpath '.:/mylib/*' MyApp

Java - System Property

System.getProperty("java.class.path")

@REM Appending additional jar files to the CLASSPATH...
IF EXIST %MY_DIR%\lib FOR %%G IN (%MY_DIR%\lib\*.jar) DO (CALL :APPEND_CLASSPATH %%~FSG)

echo %CLASSPATH%
java ....

:APPEND_CLASSPATH
SET CLASSPATH=%CLASSPATH%;%1
GOTO :EOF

See http://docs.oracle.com/javase/1.5.0/docs/tooldocs/windows/java.html#-jar

• ClassPath doc
• Setting the Classpath: Solaris and Linux - Windows
• How Classes are Found (Solaris, Linux and Windows)
• Classpath_(Java)