I'm new in programming, I'm learning Java right now. I tried to use the javac command, but the environment says that javac is an unknown command.
How to use "javac" to compile .java files from the command prompt? I'm using eclipse 1.2.2.20100216-1730, JRE 1.6 and JRE6
The JRE has the "java" program for running programs already compiled. The "javac" program is only in the JDK. Download and install the JDK. If BTW it still gives you the same error, then you need to add the javac directory to your PATH environment variable.
Before the Java virtual machine (VM) can run a Java program, the program's Java source code must be compiled into byte-code using the javac compiler. Java byte-code is a platform independent version of machine code; the target machine is the Java VM rather than the underlying architecture. To compile a Java source code file add.java, you would do the following:
javac add.java
If there are no errors in your source file, the Java compiler will produce one or more .class files (one .class file for each class defined in the add.java source file). For example, the results of a successful compile of Foo.java will produce a byte-code version of the class in a file named Foo.class.
Every public class that you write must be in a separate .java file where the first part of the file name is identical to the class name. The .java file additionally can contain code for protected and private classes.
Once you have successfully compiled your Java source code, you can invoke the Java VM to run your application's byte-code:
java <class with main method to run> [<command line args>, ...]
For example, to run the main method from the Foo class:
java Foo
Any command line arguments (arguments to add's main method) follow the class name:
java add 10 20
Such Error may occur due to two reasons:
Setting Path and classPath:
Windows XP
Windows Vista:
If you have not set the classpath and path you can access javac giving full path:
such as C:\\Java\\jdk1.7.0\\bin\\javac MyClass.java
To check the path and classpath, type these commands in a command window:
echo $PATH
echo $CLASSPATH
If you get a blank command line in response to either of these, then that particular variable has no value (it has not yet been set).
setting path and classpath through cmd:
set path=c:\j2sdk1.4.1_01\bin(Give the path of bin)
set classpath=;(or the directory where you want your class files)
Download and install JDK set environment path --> edit path in environment path and add ;/bin using javac command --> javac *.java or javac ClassName.java
When run the main method you should note to [package] name java packagename.ClassName
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