Java APIs

Hi everybody!

I'm trying to compile a file using javax.tools.JavaCompiler but I get a java.lang.NullPointerException when running the program.

Here is my code:

public boolean CompExecFile(File filename){

		boolean compRes = false;

		try {

			System.out.println(filename.getAbsolutePath());
			JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
			StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null); //line where I get the error
			Iterable<? extends JavaFileObject> compilationUnits2 = fileManager.getJavaFileObjects(filename);
			compRes = compiler.getTask(null, fileManager, null, null, null, compilationUnits2).call();
			fileManager.close();
	        if (compRes) {
	            System.out.println ("Compilation was successful");
	        } else {
	            System.out.println ("Compilation failed");
	        }
			
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}


		return compRes;

	}

There error on the line "StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);":
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException+

I've seen several examples using the parameters "null,null,null" but I don't know if it's good :(

Many thanks for your help.