ByteBuffer array() method in Java with Examples - GeeksforGeeks

03 Jun, 2021
The array() method of java.nio.ByteBuffer class is used to return the byte array that backs the taken buffer.Modifications to this buffer’s content will cause the returned array’s content to be modified, and vice versa.Invoke the hasArray() method before invoking this method in order to ensure that this buffer has an accessible backing array.
Syntax : 
public final byte[] array()
Return Value: This method returns the array that backs this buffer.Exception: This method throws the ReadOnlyBufferException, If this buffer is backed by an array but is read-only.
Below are the examples to illustrate the array() method:
Example 1:  
Java
// Java program to demonstrate// array() method import java.nio.*;import java.util.*; public class GFG {     public static void main(String[] args)    {         // Declaring the capacity of the ByteBuffer        int capacity = 4;         // Creating the ByteBuffer        try {             // creating object of ByteBuffer            // and allocating size capacity            ByteBuffer bb = ByteBuffer.allocate(capacity);             // putting the int to byte typecast value in ByteBuffer            bb.put((byte)20);            bb.put((byte)30);            bb.put((byte)40);            bb.put((byte)50);             // print the ByteBuffer            System.out.println("ByteBuffer:  "                               + Arrays.toString(bb.array()));             // getting byte array from ByteBuffer            // using array() method            byte[] arr = bb.array();             // print the byte array            System.out.println("\nbyte array: " +                                    Arrays.toString(arr));        }         catch (IllegalArgumentException e) {             System.out.println("Exception throws: " + e);        }    }}
ByteBuffer:  [20, 30, 40, 50]

byte array: [20, 30, 40, 50]
 
Example 2:  
Java
// Java program to demonstrate// array() method import java.nio.*;import java.util.*; public class GFG {     public static void main(String[] args)    {         // Declaring the capacity of the ByteBuffer        int capacity = 4;         // Creating the ByteBuffer        try {             // creating object of ByteBuffer            // and allocating size capacity            ByteBuffer bb = ByteBuffer.allocate(capacity);             // putting the int to byte typecast value            // in ByteBuffer            bb.put((byte)20);            bb.put((byte)30);            bb.put((byte)40);            bb.put((byte)50);            bb.rewind();             // print the ByteBuffer            System.out.println("Original ByteBuffer:  "                               + Arrays.toString(bb.array()));             // Creating a read-only copy of ByteBuffer            // using asReadOnlyBuffer() method            ByteBuffer bb1 = bb.asReadOnlyBuffer();            bb1.rewind();             // print the ByteBuffer            System.out.print("\nReadOnlyBuffer ByteBuffer : ");             while (bb1.hasRemaining())                System.out.print(bb1.get() + ", ");             // getting byte array from read-only            // ByteBuffer using array() method            System.out.println("\n\nTrying to get the array"                               + " from bb1 for editing");            byte[] arr = bb1.array();        }         catch (IllegalArgumentException e) {             System.out.println("Exception throws: " + e);        }         catch (ReadOnlyBufferException e) {             System.out.println("Exception throws: " + e);        }    }}
Original ByteBuffer:  [20, 30, 40, 50]

ReadOnlyBuffer ByteBuffer : 20, 30, 40, 50, 

Trying to get the array from bb1 for editing
Exception throws: java.nio.ReadOnlyBufferException
 
anikakapoor
Java-ByteBuffer
Java-Functions
Java-NIO package
Java
Java
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