HashMap

[Akhil Maharaj]

All ,

My understanding is that HashMap can not contain keys .
How come the size of the Map in the following code is 5 instead of 3?
I thought ob4 and ob3 are duplicates and they can not be inserted as keys.

Please provide What i am missing ? . here is the code

import java.util.*;
public class HashTest{
    int x;
    public HashTest(int y){
           this.x = y;
    }
    public boolean equals(Object other){
        if(other instanceof HashTest){
          return ((HashTest)other).x == this.x;
        }
        return false;
    }
 
    public int hashcode() {
 
    return 100;
   }
 
   public static void main(String [] args) {
        HashTest ob1 = new HashTest(1);
        HashTest ob2 = new HashTest(2);
        HashTest ob3 = new HashTest(3);
HashTest ob4 = new HashTest(1);
HashTest ob5 = new HashTest(1);
 

        Map mp = new HashMap();
        mp.put(ob1,"one");
        mp.put(ob2,"two");
        mp.put(ob3,"three");
        mp.put(ob4,"xxx");
        mp.put(ob5,"yyy");
 

 

 
        System.out.println("size is ="+mp.size());
 

 

   }
}
    

[ahmed yehia]

Note that you didnt override hashCode() correctly, watch case. If modified then size should be 3.

[Henry Wong]

Please provide What i am missing ?

When you override a method, make sure you get the case and signature correct. In this case, the hashCode() method has a capital C.

In the future, to prevent making this mistake, declare overriden methods with the @Override annotation, it will report an error if you are not actually overriding.

Henry

[Akhil Maharaj]

I can not believe it I did that mistake again .