4.1 �I�u�W�F�N�g��������equals

public class Test {
    static int x,y;
    static Integer w,z;
    public static void main(String args[]) {
        x = 10;
//        y = new Integer(10);  �G���[
//        w = 20;   // �G���[�������D
        z = new Integer(20);
        y = x + z.intValue();
        System.out.println("( " + x +
           " , " + y + " )" );
    }
}

public class Equivalence {
  public static void main(String[] args) {
    Integer n1 = new Integer(100);
    Integer n2 = new Integer(100);
    System.out.println(n1 == n2);
    System.out.println(n1 != n2);
  }
}

public class EqualsMethod {
  public static void main(String[] args) {
    Integer n1 = new Integer(100);
    Integer n2 = new Integer(100);
    System.out.println(n1.equals(n2));
  }
}

class Value {
  int i;
}

public class EqualsMethod2 {
  public static void main(String[] args) {
    Value v1 = new Value();
    Value v2 = new Value();
    v1.i = v2.i = 100;
    System.out.println(v1.equals(v2));
  }
}