Thread: How to modify System.out.println()

Hi everyone,

How can I change the System.out.println(x) to allways act as System.out.println(this + x)

The reason is that I have a project with thousand of java-files and in every one of them there are several System.out.println(). I would like to know what java class is printing on the console. I thought maybe there is a way to modify the System.out.print/println in the main Java library so it would allways do as write the class name or some kind of clue about which class it is first and then the content of println ... But I don't know how?

Can I modify System.out.println in Java??? Is this possible at all? //Thanks

No you cannot alter the Java API source code.

Hello,

you could create your own PrintStream and set that as System.out, try something like this.

import java.io.OutputStream;
import java.io.PrintStream;
 
public class SysOutTest {
 
    public static void main(String[] args) {
        System.out.println("This line does not have the extra text added");
 
        System.setOut(new MyPrintStream(" ADDED TEXT", System.out));
 
        System.out.println("This line will have some added text");
    }
 
    public static class MyPrintStream extends PrintStream {
 
        private final String x;
 
        public MyPrintStream(final String x, final OutputStream outputStream) {
            super(outputStream);
            this.x = x;
        }
 
        @Override
        public void println(final String string) {
            super.println(string + this.x);
        }
    }
}

I've left most of the other print methods out in this sample but if you need to implement more of them just copy the contents of the println method.

// Json

Thank you all

Yes there is a way to print the classname in java console.
For that you need to override the toString() method in the class created by you. From the toString() method return the name of the class and use “this” keyword in println() method .
Following is the codesnnipet:

package Misc;
public class B {
public String toString(){
return "B";
}
public void testPrintln(){
String str = "test string";
System.out.println(this+str);
}
public static void main(String[] arg){
new B().testPrintln();
}
}

Hope this is your solution..