Question

Today I asked many questions about Jars & JavaCompiler.
Because I haven’t been able to achieve my goal I’ll ask the whole question now:

I want a ProgramOne.jar which compiles a class out of a file and than loads this class.

Somehow I can’t achieve that with the approach which works in Eclipse (the ProgramOne not packed into a Jar).

So the approach which works in eclipse is:

File fRun = new File("someFile.java");
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
Iterable<String> options = Arrays.asList( new String[] { "-d", currentDir+"\\bin\\"} );
Iterable<? extends JavaFileObject> compUnits =  fileManager.getJavaFileObjects(fRun);
Boolean compRes = compiler.getTask(null, fileManager, null, options, null, compUnits).call();           

if(compRes == true){
    System.out.println("Compilation has succeeded");
    fileManager.close();
    ClassLoader cl = Thread.currentThread().getContextClassLoader();
    Class<?> compiledClass = cl.loadClass(someFile);
    cRun = compiledClass;
}else{
    System.out.println("Compilation error");
    fileManager.close();
    throw new Exception("Compilation Error");
}

This creates the class file in the folder <...>/ProgramOne/bin and then loads the class

How can I achieve that with the packed ProgramOne.jar?

Answer 1

If I understand what you’re trying to do, you’ll need to programmatically recreate your ProgramOne.jar file.

So:

java -jar ProgramOne.jar foo.java

1) ProgramOne.jar compiles foo.java

2) ProgramOne.jar reassembles itself to include foo.class

3) ProgramOne.jar executes foo.class

See here for one example of jar file creation.