The allocate() method of java.nio.ByteBuffer class is used to allocate a new byte buffer.
The new buffer’s position will be zero, its limit will be its capacity, its mark will be undefined, and each of its elements will be initialized to zero. It will have a backing array, and its array offset will be zero.
Syntax :
public static ByteBuffer allocate(int capacity)
Parameters: This method takes capacity, in bytes as parameter.
Return Value: This method returns the new byte buffer .
Throws: This method throws IllegalArgumentException, If the capacity is a negative integer
Below are the examples to illustrate the allocate() method:
Examples 1:
// Java program to demonstrate// allocate() 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 using putInt() method 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())); } catch (IllegalArgumentException e) { System.out.println("IllegalArgumentException catched"); } catch (ReadOnlyBufferException e) { System.out.println("ReadOnlyBufferException catched"); } }} |
Output:
Original ByteBuffer: [20, 30, 40, 50]
Examples 2:
// Java program to demonstrate// allocate() method import java.nio.*;import java.util.*; public class GFG { public static void main(String[] args) { // Declaring the capacity with negative // value of the ByteBuffer int capacity = -4; // Creating the ByteBuffer try { // creating object of ByteBuffer // and allocating size capacity System.out.println("Trying to allocate negative"+ " value in ByteBuffer"); ByteBuffer bb = ByteBuffer.allocate(capacity); // putting int to byte typecast value // in ByteBuffer using putInt() method 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())); } catch (IllegalArgumentException e) { System.out.println("Exception thrown : " + e); } catch (ReadOnlyBufferException e) { System.out.println("Exception thrown : " + e); } }} |
Output:
Trying to allocate negative value in ByteBuffer Exception thrown : java.lang.IllegalArgumentException
