Question about "java.lang.Object.equals()".

Question

public class TestEquals {
  private int a;
  private int b;
  public TestEquals(int a,int b) {
    setA(a);
    setB(b);
  public int getA() {
    return a;
  public void setA(int a) {
    this.a = a;
  public int getB() {
    return b;
  public void setB(int b) {
    this.b = b;
  public static void main(String[] args) {
    TestEquals te01 = new TestEquals(1,2);
    TestEquals te02 = new TestEquals(1,2);
    System.out.println("te01 equals to te02: " + te01.equals(te02));
    te01.setA(2);
    System.out.println("te01 equals to te02: " + te01.equals(te02));
}The result is:
te01 equals to te02: false
te01 equals to te02: false
Why the first case is false?

Answer 1

You didn't override Object.equals() in your TestEquals class. So, you are calling Object.equals(), which just compares reference values. You need to write your own equals() method (presumably, make sure te01.a==te02.a and te01.b==te02.b). Depending on what you do with your objects, you would want to override Object.hashCode(), too.