Changing System.out.println()

Question

Imagine having hundreds of java classes. In these classes there are many System.out.println(data) in different places. When printing in the console screen I cannot know which java class is printing. Of course I could open every java-file and in every System.out.println() write as:
System.out.println("This is TheNameOfJavaClass" + myData)
or
System.out.println(this.getClass().getName() + " - " + myData)...but I want a nice approach like extending or implenting some how in classes and the java classes add java-class-name when using System.out.println(myData) it becomes className + myData
Do you have any suggestion? Is there clever approach to this?
Edited by: Maria1990 on Aug 12, 2010 12:32 PM

Answer 1

You may have missed the first reply, so here just an example:
import java.io.PrintStream;
public class PrefixPrintln {
    private static class Prefixer extends PrintStream {
     public Prefixer(PrintStream ps) {
         super(ps);
     @Override
     public void println(String txt) {
         super.println(findCaller() + ": " + txt);
     // I'm not sure if other print methods will invoke println(String),
     // so you may have to overwrite other print methods as well.
     private String findCaller() {
         StackTraceElement[] elms = Thread.currentThread().getStackTrace();
         for (StackTraceElement elm : elms) {
          String name = elm.getClassName();
          if (!name.equals(this.getClass().getName())
               && !name.equals(Thread.class.getName())) {
              return name;
         return null;
    public static void main(String[] args) {
     System.setOut(new Prefixer(System.out));
     new PrefixPrintln().useSystemOut();
    private void useSystemOut() {
     System.out.println("Some message");
}