CharBuffer is part of the java.nio package and is a buffer for handling characters. It is useful for character-based input/output operations, such as text parsing, network communication, or file processing. It works similarly to ByteBuffer but specifically stores 16-bit char values.
Commonly Used Methods
Simple Program using CharBuffer
Writing and Reading Characters
import java.nio.CharBuffer;
public class SimpleCharBufferDemo {
public static void main(String[] args) {
// Create CharBuffer with capacity 10
CharBuffer buffer = CharBuffer.allocate(10);
// Put characters
buffer.put('H');
buffer.put('e');
buffer.put('l');
buffer.put('l');
buffer.put('o');
// Flip to switch to read mode
buffer.flip();
System.out.println("Reading characters from buffer:");
while (buffer.hasRemaining()) {
System.out.print(buffer.get());
}
}
}Problem Statement:
LotusJavaPrince is developing a text-processing application. Mahesh challenges him to implement a filter that reads characters from a CharBuffer, removes vowels, and rewrites the remaining characters. The application should:
- Use
CharBufferfor both input and output - Process each character one by one
- Demonstrate usage of key buffer methods:
get(),put(),flip(),clear(),rewind()
import java.nio.CharBuffer;
public class CharBufferCaseStudy {
public static void main(String[] args) {
String input = "Welcome Mahesh and LotusJavaPrince!";
System.out.println("Original: " + input);
// Wrap input string in CharBuffer
CharBuffer inputBuffer = CharBuffer.wrap(input);
CharBuffer outputBuffer = CharBuffer.allocate(input.length());
while (inputBuffer.hasRemaining()) {
char ch = inputBuffer.get();
if (!isVowel(ch)) {
outputBuffer.put(ch); // Write only consonants
}
}
// Prepare output buffer for reading
outputBuffer.flip();
// Convert to string
StringBuilder result = new StringBuilder();
while (outputBuffer.hasRemaining()) {
result.append(outputBuffer.get());
}
System.out.println("Without vowels: " + result.toString());
}
// Helper method to check for vowels
private static boolean isVowel(char ch) {
return "AEIOUaeiou".indexOf(ch) != -1;
}
}Output:
Original: Welcome Mahesh and LotusJavaPrince!
Without vowels: Wlcm Mhsh nd LtsJvPrnc!The CharBuffer class in Java NIO is a specialized buffer for handling sequences of characters efficiently. As part of the java.nio package, it provides a structured way to manage character data in memory, offering a more flexible and performant alternative to traditional character streams.
Built on top of the abstract Buffer class, CharBuffer maintains the core properties — position, limit, capacity, and mark — which give developers precise control over character read/write operations. It supports both read-only and read-write modes and allows slicing, duplicating, and compacting for complex data manipulation scenarios.