Java - Capturing System.err.println or Capturing a PrintStream

Question

Java Newbie question :

I need to capture the text being written to a printStream by a 3rd party component.

The PrintStream is defaulted to System.err, but can be changed to another PrintStream.

Looking through the docs, I couldn't find an easy way to direct the contents of a PrintStream to a string writer / buffer.

Can someone please assist?

Answer 1

PipedOutputStream pipeOut = new PipedOutputStream();
PipedInputStream pipeIn = new PipedInputStream(pipeOut);
System.setOut(new PrintStream(pipeOut));
// now read from pipeIn

Answer 2

import java.io.*;

public class Test {
    public static void main(String[] args) {
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream("errors.txt");
        } catch(IOException ioe) {
            System.err.println("redirection not possible: "+ioe);
            System.exit(-1);
        }
        PrintStream ps = new PrintStream(fos);
        System.setErr(ps);
        System.err.println("goes into file");
    }
}