why hashCode() gives different output for same object in java?

Question

I have this code

class A
{
 public static void main(String reds[])
  {
    A ob=new A();
    System.out.println("Object "+ob);
    System.out.println("HashCode "+ob.hashCode());
  }
}

Output is: Output image

The output for above code gives different value most of the time. Also, the below link mentions that printing a reference variable prints ClassName@hashcode.

printing reference variable is not printing the object's address

However, the output for printing reference varibale differs from hashCode().What is actually happening here?

Just wanted to clear my concepts of hashcode in java.

TheLostMind · Accepted Answer · 2016-10-26 05:33:40Z

2

When you call println() on your object (of type A), it prints getClass().getName() + "@" + Integer.toHexString(hashCode()) (which is the default implementation of toString() in Object class) i.e, it converts hashCode to hexString. If you do the same for your hashCode (when printing), you will get the same value.

If your class overrides toString, then it will be printed.

edited Oct 26, 2016 at 5:33

answered Sep 26, 2016 at 5:23

TheLostMind

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4 Comments

Prasad Kharkar Over a year ago

Also, directly printing an object using println() calls its toString() method which does mentioned tasks.

TheLostMind Over a year ago

@PrasadKharkar - Yes. It calls Object's toString if your class (or any of its direct parents) don't override toString()

user207421 Over a year ago

It prints the result of calling A.toString(), whatever that may be. In this case it wasn't overridden, so it printed the result of Object.toString(). None of this behaviour is attributable to println().

TheLostMind Over a year ago

@EJP - I thought that the OP's question was how className@someHexVal was being generated. Edited my answer to add the toString part

user207421 · Accepted Answer · 2016-10-23 00:46:39Z

0

Object.toString() uses the hashCode in hex. You are printing it yourself in decimal.

answered Oct 23, 2016 at 0:46

user207421

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