Question

Sorry … about this silly/stupid question, guys:

Why aren’t equals() and hashCode() being applied?

Currently they are only working as I expected for HashSet.

UPDATE

EVEN key value 5 is repeated but it doesn’t call equals and hashCode.

I want to apply it also on Value.

As just like HashSet calls equal and hashCode in this example, why hashMap is not being called equals and hashCode even if for key.

UPDATE2 – ANSWER

HashMap’s key(class->HashCode, equals) would be called.
Thank you All.
I was little bit confused on this.
🙂

    public class Employee {

        int id;
        String name; 
        int phone;

        public Employee(int id, String name, int phone) {
            this.id = id;
            this.name = name;
            this.phone = phone;
        }    
    // Getter Setter

        @Override
        public boolean equals(Object obj) {

            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            final Employee other = (Employee) obj;
            System.out.println("Employee -  equals" + other.getPhone());
            if (this.id != other.id) {
                return false;
            }
            if ((this.name == null) ? (other.name != null) : !this.name.equals(other.name)) {
                return false;
            }
            if (this.phone != other.phone) {
                return false;
            }
            return true;
        }

        @Override
        public int hashCode() {
            System.out.println("Employee -  hashCode" );
            int hash = 3;
            hash = 67 * hash + this.id;
            hash = 67 * hash + (this.name != null ? this.name.hashCode() : 0);
            hash = 67 * hash + this.phone;
            return hash;
        }
    }

____________________________________________________________________________________

public class MapClass {

    public static void main(String[] args) {
        Map<Integer,Employee> map = new HashMap<Integer,Employee>();
        map.put(1, new Employee(1, "emp", 981));
        map.put(2, new Employee(2, "emp2", 982));
        map.put(3, new Employee(3, "emp3", 983));
        map.put(4, new Employee(4, "emp4", 984));
        map.put(5, new Employee(4, "emp4", 984));
       **//UPDATE**
        map.put(5, new Employee(4, "emp4", 984));            

        System.out.println("Finish Map" + map.size());
        Set<Employee> set = new HashSet<Employee>();

        set.add(new Employee(1, "emp", 981));
        set.add(new Employee(2, "emp2", 982));
        set.add(new Employee(2, "emp2", 982));
        set.add(new Employee(3, "emp3", 983));
        set.add(new Employee(4, "emp4", 984));
        set.add(new Employee(4, "emp4", 984));

        System.out.println(set.size());
    }
}

OUTPUT IS

Finish Map5
Employee -  hashCode
Employee -  hashCode
Employee -  hashCode
Employee -  equals982
Employee -  equals982
Employee -  hashCode
Employee -  hashCode
Employee -  hashCode
Employee -  equals984
Employee -  equals984
4

Answer 1

EVEN key value 5 is repeated but it doesn’t call equals and hashCode

Yes it does call hashCode, on the key, the Integer.

I want to apply it also on Value

Dose of reality: Java HashMaps don’t work that way. They check the key only for duplicates, not the value, and this is as it should be.

If you want Employee’s hash to be checked in the Map, then it must be the key. Period.

Another possible solution is to download one of the multimaps that are available.

Edit to see that it’s calling hashCode and equals, change your Map’s key type to something like so:

class MyInt {
   private Integer i;

   public MyInt(Integer i) {
      this.i = i;
   }

   public Integer getI() {
      return i;
   }

   @Override
   public int hashCode() {
      System.out.println("MyInt HashCode: " + i.hashCode());
     return i.hashCode();
   }

   @Override
   public boolean equals(Object obj) {
      System.out.printf("MyInt equals: [%s, %s]%n", i, obj);
      if (this == obj)
         return true;
      if (obj == null)
         return false;
      if (getClass() != obj.getClass())
         return false;
      MyInt other = (MyInt) obj;
      if (i == null) {
         if (other.i != null)
            return false;
      } else if (!i.equals(other.i))
         return false;
      return true;
   }

   @Override
   public String toString() {
      return i.toString();
   }

}

Then fill your Map like so:

   Map<MyInt,Employee> map = new HashMap<MyInt,Employee>();
   map.put(new MyInt(1), new Employee(1, "emp", 981));
   map.put(new MyInt(2), new Employee(2, "emp2", 982));
   map.put(new MyInt(3), new Employee(3, "emp3", 983));
   map.put(new MyInt(4), new Employee(4, "emp4", 984));
   map.put(new MyInt(5), new Employee(4, "emp4", 984));
   map.put(new MyInt(5), new Employee(4, "emp4", 984));

and you’ll see:

MyInt HashCode: 1
MyInt HashCode: 2
MyInt HashCode: 3
MyInt HashCode: 4
MyInt HashCode: 5
MyInt HashCode: 5
MyInt equals: [5, 5]