HASHCODE

What is hashcode?

• hashCode method which is available in Object Class (In java, Object class is the parent class of every class).
• hashCode method returns unique integer for every objects.
  • i.e., Human have unique aadhar number, Every object have unique hash code.
• hashCode method calling syntax:
  • objectName.hashCode( );

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Ex 1:

public class Sample {

	public static void main(String[] args) {
		Sample sample_obj1 = new Sample();
		Sample sample_obj2 = new Sample();
		System.out.println("Print Hashcode for Sample Class Object1: " + sample_obj1.hashCode());
		System.out.println("Print Hashcode for Sample Class Object2: " + sample_obj2.hashCode());
	}	
}

Output:

Print Hashcode for Sample Class Object1: 231685785
Print Hashcode for Sample Class Object2: 114935352

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Ex 2:

public class Sample {

	public static void main(String[] args) {
		Sample sample_obj1 = new Sample();
		Sample sample_obj2 = new Sample();
		System.out.println("Print Hashcode for Sample Class Object1: " + sample_obj1.hashCode());
		System.out.println("Print Hashcode for Sample Class Object2: " + sample_obj2.hashCode());
	}	
	
	public int hashCode()
	{
		return 123;
	}
}

Output:

Print Hashcode for Sample Class Object1: 123
Print Hashcode for Sample Class Object2: 123

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Code Explanation:

• In Ex 1, we call the hashCode method. Sample class doesn’t have own hashCode method.
• Object class is the parent class of every class. Object class contains hashCode method.
• Hence, Sample class object calling it’s parent class(Object class) hashCode method.
• Parent class hashCode method returns unique integer value for every object.

• In Ex 2, Sample class have it’s own hashCode method.
• Here, Sample class hashCode method overrides it’s Parent class(Object Class) hashCode method.

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