ByteBuffer hashCode() method in Java with Examples

The hashCode() method of java.nio.ByteBuffer class is used to return the current hash code of this buffer. The hash code of a byte buffer depends only upon its remaining elements; that is, upon the elements from position() up to, and including, the element at limit() – 1. Because buffer hash codes are content-dependent, it is inadvisable to use buffers as keys in hash maps or similar data structures unless it is known that their contents will not change. 

Syntax:

public int hashCode()

Return Value: This method returns the current hash code of this buffer. Below are the examples to illustrate the hashCode() method: Examples 1:

Java

// Java program to demonstrate
// hashCode() method

import java.nio.*;
import java.util.*;

public class GFG {

    public static void main(String[] args)
    {
        // creating object of ByteBuffer
        // and allocating size capacity
        ByteBuffer bb = ByteBuffer.allocate(12);

        // putting the int value in the bytebuffer
        bb.asIntBuffer()
            .put(10)
            .put(20)
            .put(30);

        // rewind the Bytebuffer
        bb.rewind();

        // print the ByteBuffer
        System.out.println("Original ByteBuffer: ");
        for (int i = 1; i <= 3; i++)
            System.out.print(bb.getInt() + " ");

        // rewind the Bytebuffer
        bb.rewind();

        // Reads the Int at this buffer's current position
        // using hashCode() method
        int value = bb.hashCode();

        // print the int value
        System.out.println("\n\nByte Value: " + value);
    }
}

Output:

Original ByteBuffer: 
10 20 30 

Byte Value: -219122491

Examples 2:

Java

// Java program to demonstrate
// hashCode() method

import java.nio.*;
import java.util.*;

public class GFG {

    public static void main(String[] args)
    {
        // creating object of ByteBuffer
        // and allocating size capacity
        ByteBuffer bb = ByteBuffer.allocate(12);

        // Reads the Int at this buffer's current position
        // using hashCode() method
        int value = bb.hashCode();

        // print the int value
        System.out.println("Byte Value: " + value);
    }
}

Output:

Byte Value: -293403007

Reference: https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#hashCode–