**`java.nio.CharBuffer`** is a class that can be used to store a buffer of characters. The **`put()`** method of the `java.nio.CharBuffer` class is used to write a character to a buffer. The `CharBuffer.put()` method writes the character at the current #key# position: The index of the next element of the buffer that will be read or written #key# of the buffer and increments the position by one.


# Declaration
The `CharBuffer.put()` method can be declared as:
```java
buff1.put(x);
```
* `buff1`: The `CharBuffer` in which the character `x` will be written.
* `x`: The character that will be written to `buff1`.

# Return value
The `CharBuffer.put()` method returns the `CharBuffer` `buff1` after writing the character `x` to it.

> Note:
>* If the position of `buff1` is not less than the #key# limit: The first index of the buffer that should not be read or written #key# of `buff1`, the `BufferOverflowException` is thrown.
>* If `buff1` is read-only, the `ReadOnlyBufferException` is thrown.

# Example
## Example 1
Consider the code snippet below, which demonstrates the use of the `CharBuffer.put()` method.

import java.nio.*;
import java.util.*;
public class main {
   public static void main(String[] args) {
      int n1 = 5;
      int n2 = 4;
      try {
         CharBuffer buff1 = CharBuffer.allocate(n1);
         buff1.put('a');
         buff1.put('c');
         System.out.println("buff1: " + Arrays.toString(buff1.array()));
         System.out.println("position: " + buff1.position());
         
      } catch (IllegalArgumentException e) {
         System.out.println("Error!!! IllegalArgumentException");
      } catch (ReadOnlyBufferException e) {
         System.out.println("Error!!! ReadOnlyBufferException");
      }
   }
}

## Explanation
* A `CharBuffer` `buff1` is declared in *line 8*.
* An element is written to `buff1` using the `CharBuffer.put()` method in *line 9*. After adding the first element, the position of `buff1` is incremented from 0 to 1.
* Another element is written to `buff1` using the `CharBuffer.put()` method in *line 10*. After adding the second element, the position of `buff1` is incremented from 1 to 2.

## Example 2

As explained above, using the `CharBuffer.put()` method on a read-only buffer throws the `ReadOnlyBufferException`. Consider the code snippet below that demonstrates this.

import java.nio.*;
import java.util.*;
public class main {
   public static void main(String[] args) {
      int n1 = 5;
      int n2 = 4;
      try {
         CharBuffer buff1 = CharBuffer.allocate(n1);

         CharBuffer buff2 = buff1.asReadOnlyBuffer();
         buff2.put('a');
         buff2.put('c');
         System.out.println("buff2: " + Arrays.toString(buff2.array()));
         System.out.println("position: " + buff2.position());
         
      } catch (IllegalArgumentException e) {
         System.out.println("Error!!! IllegalArgumentException");
      } catch (ReadOnlyBufferException e) {
         System.out.println("Error!!! ReadOnlyBufferException");
      }
   }
}

## Explanation
* A `CharBuffer` `buff1` is declared in *line 8*.
* A `CharBuffer` `buff2` is declared in *line 10* that is the read-only copy of `buff1`.
* The `CharBuffer.put()` method is used in *line 11* to try writing a value to `buff2`. `ReadOnlyBufferException` is thrown because `buff2` is read-only and cannot be modified. 

What is the CharBuffer put() method in Java?

Declaration

Return value

Example

Example 1

Explanation

Example 2

Explanation