CharBuffer allocate() method in Java with Examples

The allocate() method of java.nio.CharBuffer Class is used to allocate a new char buffer next to the existing 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 CharBuffer allocate(int capacity)

Parameter: This method takes the new buffer’s capacity, in char, as a parameter.

Return Value: This method returns the new char buffer.

Exception: This method throws the IllegalArgumentException if the capacity is a negative integer.

Below program illustrates the allocate() method:

Examples 1:

Java

// 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 CharBuffer
        char capacity = 10;

        // Creating the CharBuffer

        // creating object of Charbuffer
        // and allocating size capacity
        CharBuffer fb = CharBuffer.allocate(capacity);

        // putting the value in charbuffer
        fb.put('a');
        fb.put(3, 'b');

        // Printing the CharBuffer
        System.out.println("ChartBuffer: "
                           + Arrays.toString(fb.array()));
    }
}

Output:

ChartBuffer: [a, , , b, , , , , , ]

Examples 2: To demonstrate IllegalArgumentException

Java

// 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 CharBuffer
        // by negative integer
        int capacity = -10;

        // Creating the CharBuffer
        try {

            // creating object of CharBuffer
            // and allocating size with negative integer
            System.out.println("Trying to allocate a negative integer");

            CharBuffer fb = CharBuffer.allocate(capacity);
        }
        catch (IllegalArgumentException e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

Output:

Trying to allocate a negative integer
Exception thrown: java.lang.IllegalArgumentException