override - Example of 2 objects in java having same hash value but equals method returns false on them -

we know if equals method returns true, 2 objects equal.

can give example 2 objects have same hash value different?

i'm assuming you're familiar contract(s) associated overriding equals() , hashcode(), , implications of collision-prone hashcode implementation. given that, following trivial example uses object holds 2 integers , implements simple hashcode, , demonstrates how easy have 2 objects aren't equal have same hashcode. providing more sophisticated hashcode algorithm can alleviate this.

the output of running main is:

hashcodes: ih1: 6, ih2: 6 equals: false 

example code:

package example.stackoverflow;  public class intholder {     private integer primarydata;     private integer secondarydata;      public intholder(integer primarydata, integer secondarydata)     {         this.primarydata = primarydata;         this.secondarydata = secondarydata;     }      @override     public int hashcode()     {         return ((primarydata == null) ? 0 : primarydata.hashcode()) +                 ((secondarydata == null) ? 0 : secondarydata.hashcode());     }      @override     public boolean equals(object obj)     {         if (this == obj)             return true;         if (obj == null)             return false;         if (getclass() != obj.getclass())             return false;         intholder other = (intholder) obj;         if (primarydata == null)         {             if (other.primarydata != null)                 return false;         }         else if (!primarydata.equals(other.primarydata))             return false;         if (secondarydata == null)         {             if (other.secondarydata != null)                 return false;         }         else if (!secondarydata.equals(other.secondarydata))             return false;         return true;     }      public static void main(string[] args)     {         intholder ih1 = new intholder(1, 5);         intholder ih2 = new intholder(3, 3);          system.out.println("hashcodes: ih1: " + ih1.hashcode() + ", ih2: " + ih2.hashcode());         system.out.println("equals: " + ih1.equals(ih2));     } } 

for reference, eclipse's auto-generated hashcode() intholder class is:

@override public int hashcode() {     final int prime = 31;     int result = 1;     result = prime * result             + ((primarydata == null) ? 0 : primarydata.hashcode());     result = prime * result             + ((secondarydata == null) ? 0 : secondarydata.hashcode());     return result; }