How do I redirect standard output to a file using System.out.println()?

System.out.println() is used to print messages on the console.

System is a class defined in the java.lang package. out is an instance of PrintStream, which is a public and static member of the class System. As all instances of PrintStream class have a public method println().

System.out is a static PrintStream that writes to the console. We can redirect the output to a different PrintStream using the System.setOut() method which takes a PrintStream as a parameter.

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.PrintStream;

public class SetPrintStream {

  public static void main(String[] args) throws FileNotFoundException{

           System.out.println("Print on console");

          

           // Store console print stream.

           PrintStream ps_console = System.out;

          

           File file = new File("file.txt");

           FileOutputStream fos = new FileOutputStream(file);

          

           // Create new print stream for file.

           PrintStream ps = new PrintStream(fos);

          

           // Set file print stream.

           System.setOut(ps);

           System.out.println("Print in the file !!");

           // Set console print stream.

           System.setOut(ps_console);

           System.out.println("Console again !!");

 }

}

Output:

Print on console

Console again !!

    

new file.txt will be created.