wrap(byte[] array)
The wrap() method of java.nio.ByteBuffer Class is used to wraps a byte array into a buffer. The new buffer will be backed by the given byte array; that is, modifications to the buffer will cause the array to be modified and vice versa. The new buffer’s capacity and limit will be array.length, its position will be zero, and its mark will be undefined. It’s backing array will be the given array, and its array offset will be zero.
Syntax:
public static ByteBuffer wrap(float[] array)
Parameters: This method takes a float array as parameter which is the array that will back this buffer.
Return Value: This method returns the new byte buffer.
Below are the examples to illustrate the wrap() method:
Examples 1:
// Java program to demonstrate// wrap() method import java.nio.*;import java.util.*; public class GFG { public static void main(String[] args) { // Declare and initialize the byte array byte[] bbb = { 10, 20, 30 }; // print the byte array length System.out.println("Array length : " + bbb.length); // print the byte array element System.out.println("\nArray element : " + Arrays.toString(bbb)); // wrap the byte array into byteBuffer // using wrap() method ByteBuffer byteBuffer = ByteBuffer.wrap(bbb); // Rewind the ByteBuffer byteBuffer.rewind(); // print the byte buffer System.out.println("\nbyteBuffer : " + Arrays.toString(byteBuffer.array())); // print the ByteBuffer capacity System.out.println("\nbyteBuffer capacity : " + byteBuffer.capacity()); // print the ByteBuffer position System.out.println("\nbyteBuffer position: " + byteBuffer.position()); }} |
Array length : 3 Array element : [10, 20, 30] byteBuffer : [10, 20, 30] byteBuffer capacity : 3 byteBuffer position: 0
Reference: https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#wrap-byte:A-
wrap(byte[] array, int offset, int length)
The new buffer will be backed by the given byte array; that is, modifications to the buffer will cause the array to be modified and vice versa. The new buffer’s capacity will be array.length, its position will be offset, its limit will be offset + length, and its mark will be undefined. It’s backing array will be the given array, and its array offset will be zero.
Syntax :
public static ByteBuffer wrap(byte[] array,
int offset, int length)
Parameters: This method takes following parameters:
- array: The array that will back the new buffer.
- offset: The offset of the subarray to be used; must be non-negative and no larger than array.length. The new buffer’s position will be set to this value.
- length: The length of the subarray to be used; must be non-negative and no larger than array.length – offset. The new buffer’s limit will be set to offset + length.
Return Value: This method returns the new byte buffer.
Throws: This method throws the IndexOutOfBoundsException(If the preconditions on the offset and length parameters do not hold) .
Below are the examples to illustrate the wrap() method:
Examples 1:
// Java program to demonstrate// wrap() method import java.nio.*;import java.util.*; public class GFG { public static void main(String[] args) { // Declare and initialize the byte array byte[] bbb = { 10, 20, 30 }; // print the byte array length System.out.println("Array length : " + bbb.length); // print the byte array element System.out.println("\nArray element : " + Arrays.toString(bbb)); // wrap the byte array into ByteBuffer // using wrap() method ByteBuffer byteBuffer = ByteBuffer.wrap(bbb, 0, bbb.length); // Rewind the bytebuffer byteBuffer.rewind(); // print the byte buffer System.out.println("\nbyteBuffer : " + Arrays.toString(byteBuffer.array())); // print the ByteBuffer capacity System.out.println("\nbyteBuffer capacity : " + byteBuffer.capacity()); // print the ByteBuffer position System.out.println("\nbyteBuffer position: " + byteBuffer.position()); }} |
Array length : 3 Array element : [10, 20, 30] byteBuffer : [10, 20, 30] byteBuffer capacity : 3 byteBuffer position: 0
Examples 2: To demonstrate NullPointerException
// Java program to demonstrate// asReadOnlyBuffer() method import java.nio.*;import java.util.*; public class GFG { public static void main(String[] args) { // Declare and initialize the byte array byte[] bbb = { 10, 20, 30 }; // print the byte array length System.out.println("Array length : " + bbb.length); // print the byte array element System.out.println("\nArray element : " + Arrays.toString(bbb)); try { // wrap the byte array into byteBuffer // using wrap() method System.out.println("\nHere " + "offset and length does not hold" + " the required condition "); ByteBuffer byteBuffer = ByteBuffer.wrap(bbb, 1, bbb.length); // Rewind the bytebuffer byteBuffer.rewind(); // print the byte buffer System.out.println("\nbyteBuffer : " + Arrays.toString(byteBuffer.array())); // print the byteBuffer capacity System.out.println("\nbytebuffer capacity : " + byteBuffer.capacity()); // print the byteBuffer position System.out.println("\nbytebuffer position: " + byteBuffer.position()); } catch (IndexOutOfBoundsException e) { System.out.println("Exception throws: " + e); } }} |
Array length : 3 Array element : [10, 20, 30] Here offset and length does not hold the required condition Exception throws: java.lang.IndexOutOfBoundsException
Reference: https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#wrap-byte:A-int-int-
