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Difference between .class, .jar, .java and others

André Asantos
Ranch Hand

Joined: Nov 23, 2009
Posts: 234
hello guys,

can you help me please saying me the difference between .class, .jar, .java and others?

thanks in advance!

take care!
André AS
São Paulo - Brazil
Paul Sturrock

Joined: Apr 14, 2004
Posts: 10336

A java file contains Java code. A Java file is compiled to produce a class file that can be loaded by the JVM. The contents of a class file are rather well explained here. A Jar file is an archive of otherfile, most likely class files.

As for "others", which others did you have in mind?

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André Asantos
Ranch Hand

Joined: Nov 23, 2009
Posts: 234
I loved your reply...

In other words .class means the code that is interpreted by the JVM, the .java is a extension from the class and the .jar is the Java archive, right?

see you, take care!
André AS
Rajeev Trikha
Ranch Hand

Joined: Jan 29, 2010
Posts: 85
.java is your source file which you pass to the compiler (javac) to produce .class file. jar can contain your classes. If you are compiling a class which needs other classes you can have a syntax like

javac -classpath myApp.jar

The JVM interpreter always work with the bytecode in the .class file.

To feel comfortable with jar, see some online tutorials but basically the key flags are

jar -tf myJar.jar for display -xf for extract and -cf for create.

Rajeev Trikha (SCJP 6)
I agree. Here's the link:
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