.class vs .java

Question

What's the difference between a .class file and a .java file? I am trying to get my applet to work but currently I can only run it in Eclipse, I can't yet embed in HTML. Thanks

**Edit: How to compile with JVM then?

regarding your edit... the JDK comes with a compiler called javac. — Fredrik, Jun 18 '09 at 21:42
@Devoted: Yes. If it's a standalone app, you could then run: java myFile (or whatever you named the class, but it should be myFile). — Michael Myers, Jun 18 '09 at 21:46

score 62 · Accepted Answer · edited Jun 25 '13 at 20:47

62

A .class file is a compiled .java file.

.java is all text and is human readable.
.class is binary (usually).

You compile a java file into a class file by going to the command line, navigating to the .java file, and running

javac "c:\the\path\to\your\file\yourFileName.java"

You must have a java SDK installed on your computer (get it from Oracle), and make sure the javac.exe file is locatable in your computer's PATH environment variable.

Also, check out Java's Lesson 1: Compiling & Running a Simple Program

If any of this is unclear, please comment on this response and I can help out :)

edited Jun 25 '13 at 20:47

TMB

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answered Jun 18 '09 at 21:46

Brian

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What do you mean when you say `.class` files are usually binary? When are they not? – Mohit Motwani Sep 27 '19 at 06:41

score 32 · Answer 2 · answered Jun 18 '09 at 21:40

32

.class -> compiled (for JVM)
.java -> source (for humans)

answered Jun 18 '09 at 21:40

dfa

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score 6 · Answer 3 · answered Jun 18 '09 at 21:40

A .java file contains your Java source code while a .class file contains the Java bytecode produced by the Java compiler. It is your .class files that run on the JVM to execute a Java application.

It is the .class files you will use when you deploy your applet.

score 4 · Answer 4 · edited Jun 06 '20 at 20:14

4

.java files are source files, while .class files are compiled (bytecode) classes.

Use javac to compile source into bytecode.

edited Jun 06 '20 at 20:14

fospathi

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answered Jun 18 '09 at 21:40

Malcolm

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dfa beat me to the punch by 22 seconds. ;) – Malcolm Jun 18 '09 at 21:40

score 3 · Answer 5 · answered Jun 18 '09 at 21:40

3

.java usually holds your code in clear text

.class contains the byte code of your .java. Think of it as a compiled version of the .java file

answered Jun 18 '09 at 21:40

Eric

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score 1 · Answer 6 · answered Feb 09 '16 at 15:02

person can be defined as a class Person. This class should reside in a Java source code file (Person.java). Using this Java source code file, the Java compiler (javac.exe on Windows or javac on Mac OS X/Linux/UNIX) generates bytecode (compiled code for the Java Virtual Machine) and stores it in Person.class.

score 1 · Answer 7 · edited Nov 25 '16 at 11:38

1

Java files is an human readable language (for example, the code we write in Eclipse/any other IDE).

Class files are in byte-code compiled for Java Virtual Machine (JVM).

edited Nov 25 '16 at 11:38

Ricardo Rocha

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answered Nov 25 '16 at 09:42

Dattatreyo Paul

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.class vs .java

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