Why two objects of employee are not equal?

Question

I have created an Employee class having name and employeeNo . I am overriding equals and hashcode method.

@Override
public boolean equals(Object obj) {
       final Employee other = (Employee) obj;

 if (this.employeeNo == other.employeeNo && this.name.equals(other.name)) {
                return true;
            }

            return false;
    }

@Override
public int hashCode() {
    int hash = 3;
    hash = 53 * hash + (this.name != null ? this.name.hashCode() : 0);
    hash = 53 * hash + this.employeeNo;
    return hash;
}

My test class

Employee p = new Employee();
        p.setName("v");
        p.setEmployeeNo(1);

        Employee p1 = new Employee();
        p.setName("v");
        p.setEmployeeNo(1);

        System.out.println(p==p1); // Print false . why?

Your `equals`methods should verify that obj is not `null` before the cast. — Julien, Sep 05 '13 at 17:06
`==` compares references, it doesn't call a method like `equals` — Peter Lawrey, Sep 05 '13 at 17:08

nanofarad · Accepted Answer · 2013-09-05T17:09:54.217

10

System.out.println(p==p1);

does not implicitly call equals(. It compares the references which are different here. Use:

System.out.println(p.equals(p1));

instead.

Also:

Employee p1 = new Employee();
p.setName("v");
p.setEmployeeNo(1);

uses p, where p1 should be used.

edited Sep 05 '13 at 17:09

answered Sep 05 '13 at 17:02

nanofarad

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Crap..!! I did a blunder.. :( – Thinker Sep 05 '13 at 17:04
@Thinker I suggest editing your comment to read "crap" instead. – nanofarad Sep 05 '13 at 17:04
And also i am trying to print the hashcode of p and p1. They both are different . They should be same right? – Thinker Sep 05 '13 at 17:09
1

@Thinker Found it. You set the fields of `p` twice and never set `p1`. – nanofarad Sep 05 '13 at 17:10
you are genius. Thanks. I learnt new thing today. Never do copy paster – Thinker Sep 05 '13 at 17:11

score 0 · Answer 2 · answered Sep 05 '13 at 17:09

0

The error maybe in this line:

if (this.employeeNo == other.employeeNo && this.name.equals(other.name)) {
    return true;
}

This condition will only become true, if booth employeeNr are the same. If employeeNr is of type Integer and not int.

If is false becuase equals() is not calles.

a==b will check iif the objects are the same

e.equals(b) will call the equals()

answered Sep 05 '13 at 17:09

Christian Kuetbach

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Integer a = new Integer(1); Integer b = new Integer(1); a==b will become true? – Christian Kuetbach Sep 05 '13 at 17:12
No.That is the mistake i did. – Thinker Sep 05 '13 at 17:12
@hexafraction You're wrong, you should read this thread http://stackoverflow.com/questions/4428774/why-java-does-not-see-that-integers-are-equal – Julien Sep 05 '13 at 17:14

Why two objects of employee are not equal?

2 Answers2