What is the use of rt.jar file in java?

Question

Possible Duplicate:
Why do we use rt.jar in a java project?

I am very confused to knowing about rt.jar file.

What is the role of rt.jar file or use of rt.jar file in java??

Thanks.

Solution 1

rt.jar contains all of the compiled class files for the base Java Runtime environment. You should not be messing with this jar file.

For MacOS it is called classes.jar and located under /System/Library/Frameworks/<java_version>/Classes . Same not messing with it rule applies there as well :).

http://javahowto.blogspot.com/2006/05/what-does-rtjar-stand-for-in.html

Solution 2

Your question is already answered here :

• Why do we use rt.jar file in java project ?

Basically, rt.jar contains all of the compiled class files for the base Java Runtime ("rt") Environment. Normally, javac should know the path to this file

Also, a good link on what happens if we try to include our class file in rt.jar.

Comments

[djangofan]

I heard that MacOSX doesnt have this file. If so, why?

[CoolBeans]

It's there in MacOSX under a different name classes.jar and it is under /System/Library/Frameworks/<java_version>/Classes .

[Jay]

note - as of java 1.7, apple no longer distributes the jdk. The jdk from Oracle is in a different location /Library/Java/JavaVirtualMachines/jdk1.7.0_xx.jdk and has rt.jar not classes.jar

[Bludzee]

The "what happens" link location (provided in February 2011) is broken (October 2015).

[z11i]

Usually you are able to find the jar file at $JAVA_HOME/jre/lib/rt.jar

[Marco Schoolenberg]

This is a very old answer, but it is still true after all these years. I figured out today.