java hashcode and equals

Question

Create the hashCode and equals method for the following class.

private static class MyOb {

    private String name;
    private Integer quality;
    private final int MAXIMUM = 23;

}

I could not solve this question

are you trying to get your homework done?. Put some efforts first — shikjohari, Mar 06 '15 at 06:08
actually i was asked in the interview and i could not answer — prem, Mar 06 '15 at 06:10
no it is not we just have to create hashcode and equals method — prem, Mar 06 '15 at 06:20

score 2 · Accepted Answer · answered Mar 06 '15 at 06:18

2

Java class has default hashCode and equals method method implemented through super class. If u want to over ride them u can by following:

class MyOb {

private String name;
private Integer quality;
private final int MAXIMUM = 23;

@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((name == null) ? 0 : name.hashCode());
    result = prime * result + ((quality == null) ? 0 : quality.hashCode());
    return result;
}
@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    MyOb other = (MyOb) obj;
    if (name == null) {
        if (other.name != null)
            return false;
    } else if (!name.equals(other.name))
        return false;
    if (quality == null) {
        if (other.quality != null)
            return false;
    } else if (!quality.equals(other.quality))
        return false;
    return true;
}

}

Note: class cannot be private or static

answered Mar 06 '15 at 06:18

Naresh kumar

1,069
1
7
21

Why have you used MAXIMUM? It's just a constant – Adam Mar 06 '15 at 06:19
sorry changed accordingly thanks for remembering – Naresh kumar Mar 06 '15 at 06:21
Might be worth pointing out the eclipse generate hashcode/equals which I'm guessing you used. – Adam Mar 06 '15 at 06:23
yeah generated code using eclipse IDE,but my intention is to let him know these are default methods and can be overridden – Naresh kumar Mar 06 '15 at 06:28
Inner classes can be `private` and/or `static` -> http://docs.oracle.com/javase/tutorial/java/javaOO/nested.html – halex Mar 06 '15 at 06:48
Yes it can be but I refered to normal class, thanks for pointing out. – Naresh kumar Mar 06 '15 at 06:52

score -1 · Answer 2 · answered Mar 06 '15 at 06:29

-1

if you want see hash code of class. create object

    Myob myObject=new Myob();
    System.out.println(myObject);

if want to equals method

    myObject.equals(which one you want to campare);

answered Mar 06 '15 at 06:29

subhakar patnala

319
1
4
15

java hashcode and equals

2 Answers2