Demonstrates standard I/O redirection : IO redirection « File « Java Tutorial

1. Java Tutorial
2. File
3. IO redirection

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;

public class MainClass {
  public static void main(String[] args) throws IOException {
    PrintStream console = System.out;
    BufferedInputStream in = new BufferedInputStream(new FileInputStream("Redirecting.java"));
    PrintStream out = new PrintStream(new BufferedOutputStream(new FileOutputStream("test.out")));
    System.setIn(in);
    System.setOut(out);
    System.setErr(out);
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String s;
    while ((s = br.readLine()) != null)
      System.out.println(s);
    out.close(); 
    System.setOut(console);
  }
}