//Programm zur Erlaeuterung von String-Referenzen
public class Strings {
  public static void main(String[] args) {
    String a = "Hello, world!";
    String b = "Hello, world!!".substring(0, 13);
    String c = "Hello, ";
    c = c + "world!";
    String d = "Hello, w"+"orld!";
    String e = a.substring(0, 13);
    System.out.println((a == b) + " " + a.equals(b));
    System.out.println((a == c) + " " + a.equals(c));
    System.out.println((a == d) + " " + a.equals(d));
    System.out.println((a == e) + " " + a.equals(e));
  }
}