Java - Integer hashCode() method

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Description

The Java Integer hashCode() method returns a hash code for this Integer.

Declaration

Following is the declaration for java.lang.Integer.hashCode() method

public int hashCode()

Parameters

NA

Return Value

This method returns a hash code value for this object, equal to the primitive int value represented by this Integer object.

Exception

NA

Getting HashCode of a Integer having Positive Value Example

The following example shows the usage of Integer hashCode() method to get a hashcode of an integer. We've created a Integer variable and assigned it an Integer object created using a positive int value. Then using hashCode() method, we're printing the hashcode of the Integer object.

package com.tutorialspoint;

public class IntegerDemo {
   public static void main(String[] args) {
      Integer i = new Integer("20");
    
      /* returns a hash code value for this object, equal to the primitive
         int value represented by this Integer object */
      int retval = i.hashCode();
      System.out.println("Value = " + retval);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Value = 20

Getting HashCode of a Integer having Negative Value Example

The following example shows the usage of Integer hashCode() method to get a hashcode of an integer. We've created a Integer variable and assigned it an Integer object created using a negative int value. Then using hashCode() method, we're printing the hashcode of the Integer object.

package com.tutorialspoint;

public class IntegerDemo {
   public static void main(String[] args) {
      Integer i = new Integer("-20");
    
      /* returns a hash code va
Getting Integer from a System Property Example
         int value represented by this Integer object */
      int retval = i.hashCode();
      System.out.println("Value = " + retval);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Value = -20

Getting HashCode of a Integer having Zero Value Example

The following example shows the usage of Integer hashCode() method to get a hashcode of an integer. We've created a Integer variable and assigned it an Integer object created using a zero int value. Then using hashCode() method, we're printing the hashcode of the Integer object.

package com.tutorialspoint;

public class IntegerDemo {
   public static void main(String[] args) {
      Integer i = new Integer("0");
    
      /* returns a hash code value for this object, equal to the primitive
         int value represented by this Integer object */
      int retval = i.hashCode();
      System.out.println("Value = " + retval);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Value = 0

Getting HashCode of a Integer having Negative Zero Value Example

The following example shows the usage of Integer hashCode() method to get a hashcode of an integer. We've created a Integer variable and assigned it an Integer object created using a negative zero int value. Then using hashCode() method, we're printing the hashcode of the Integer object.

package com.tutorialspoint;
public class IntegerDemo {
   public static void main(String[] args) {
      Integer i = new Integer("-0");
    
      /* returns a hash code value for this object, equal to the primitive
         int value represented by this Integer object */
      int retval = i.hashCode();
      System.out.println("Value = " + retval);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Value = 0