How to compile a Java program using another program?

Question

all am working a project for compiling and running a java source code via my application. here am stuck will explain my environment here.. java 1.6.0_35 32bit and eclipse indigo using operating system windows 64 bit
when i used this code

String command = "javac "+file.getAbsolutePath();
System.out.println(command);
Process p = Runtime.getRuntime().exec(command);`

got this exception ..think error show file doesnt exist but i checked it,which is here and when i execute via command line which compiles,but the eclipse shows this error

java.io.IOException: Cannot run program "javac": CreateProcess error=2, The system cannot find the file specified
at java.lang.ProcessBuilder.start(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)`

can anyone fix this ,i tried a lot ..

It means the compiler javac is not in your path. I would try using the full path name to the javac. — Peter Lawrey
– Peter Lawrey, Commented Oct 2, 2012 at 7:29
u hum no way bro,i tried that already,i can compile the java source code through commandline :( — J.K
– J.K, Commented Oct 2, 2012 at 7:32
is it ` C:\Users\user>javac D:\Project\ServerCodeB\WebContent\Programs\Hello.java C:\Users\user> ` — J.K
– J.K, Commented Oct 2, 2012 at 7:39

Matteo · Accepted Answer · 2012-10-02 07:52:35Z

3

You don't need to use the command line, you can access javac programmatically:

JavaCompiler javac = ToolProvider.getSystemJavaCompiler();
javac.run(null, null, null, arguments);

See

The Java 6.0 Compiler API
and http://openjdk.java.net/groups/compiler/guide/compilerAPI.html for examples

It is portable (works on other systems) and will avoid problems with paths and command line.

edited Oct 2, 2012 at 7:52

answered Oct 2, 2012 at 7:32

Matteo

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3 Comments

Jesper Over a year ago

It is only portable as long as you are using Oracle's Java implementation - the class com.sun.tools.javac.Main is most likely not available in for example IBM's implementation. It's not even guaranteed to work on future versions of Oracle's Java.

Matteo Over a year ago

@Jesper: you are right, I meant more that it is usable on more systems (Windows, Linux, ...)

Matteo Over a year ago

Edited with a more portable version (the user is using 1.6 so it should be OK)

Rohit Jain · Accepted Answer · 2012-10-02 07:35:39Z

2

You can use Java 6 Compiler API . Also this link might be useful..

answered Oct 2, 2012 at 7:35

Rohit Jain

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Comments

Bertjan Broeksema · Accepted Answer · 2012-10-02 07:36:16Z

1

Your problem seems not so much that the file you want to compile is not found, but that the javac command itself is not found. Make sure that the Runtime can find the javac executable, eventually by passing the "PATH=/path/to/java/dir" to exec.

See: Runtime.exec(command, enviroment, dir)

answered Oct 2, 2012 at 7:36

Bertjan Broeksema

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