Does java --classpath override CLASSPATH or append to it? [duplicate]

Question

If I have

CLASSPATH=/blah;/foo

Then run

java -cp bar.jar com.yourcompany.SomeMain

Is the classpath now

bar.jar

OR is it

/blah;/foo;bar.jar

Basically does the command line switch override or augment the existing CLASSPATH?

Answer 1

Looks like the -cp option overrides the CLASSPATH environment variable.

$ export CLASSPATH=Tests
$ java Printf
Team Name                      No. of Wins          No. of Losses        
Bobcats                        0                    0                    
Tigers                         1                    1                    
Lions                          2                    2                    
Cheetahs                       3                    3                    
Jackals                        4                    4                    
Leopards                       5                    5                    
Snow Leopards                  6                    6                    
Cougars                        7                    7                    
Mountain Lions                 8                    8                    
Bobcats                        9                    9                    
$ java -cp . Printf
Error: Could not find or load main class Printf

The CLASSPATH environment variable is still set to the folder Tests, however, when I use the -cp option it overrides it, and changes the classpath to ., the current directory, so my class file can no longer be found.

Answer 2

yes!, the cp or classpath option overrides the system variable. for more information

http://docs.oracle.com/javase/1.5.0/docs/tooldocs/windows/java.html

Answer 3

The -cp command line switch overrides. In fact, a few other things override the CLASSPATH environment variable like the -jar switch, or IDE-specific classpath settings.

In any case, if you want to have a quick look at which classpath gets referenced when running your code, you can consider displaying this line in your class.

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