자바

java.lang.System

.out // static; java.io.PrintStream

.print()

.println()

.printf() or .format() // 자바 5.0

.err // static; java.io.PrintStream

.println()

.in // static; java.io.InputStream

.read()

import java.io.*;

public class Echo {

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

    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    String s;

    while((s = in.readLine()) != null && s.length() != 0) { System.out.println(s); } // An empty line or Ctrl-Z terminates the program    

  }

}