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StringBuffer

What Is StringBuffer?​

StringBuffer is a class in Java used to create mutable strings that are thread-safe.

Unlike String, which is immutable, StringBuffer allows modification of the same object without creating new objects.

StringBuffer = Mutable and thread-safe sequence of characters

It is mainly used in multi-threaded environments where thread safety is required.

Simple Example​

StringBuffer sb = new StringBuffer("Hello");

sb.append(" World");

System.out.println(sb); // Hello World

Common StringBuffer Methods

1. append()​

Adds text to the end of the string.

StringBuffer sb = new StringBuffer("Java");

sb.append(" Programming");

System.out.println(sb); // Java Programming

2. insert()​

Inserts text at a specified index.

StringBuffer sb = new StringBuffer("Java");

sb.insert(4, " Language");

System.out.println(sb); //  Java Language

3. replace()​

Replaces characters between specified indexes.

StringBuffer sb = new StringBuffer("Java Programming");

sb.replace(5, 16, "Language");

System.out.println(sb); //  Java Language

4. delete()​

Deletes characters from the string.

StringBuffer sb = new StringBuffer("Java Programming");

sb.delete(4, 16);

System.out.println(sb); // Java

5. reverse()​

Reverses the characters in the string.

StringBuffer sb = new StringBuffer("Java");

sb.reverse();

System.out.println(sb); // avaJ

6. capacity()​

Returns the current capacity of the buffer.

StringBuffer sb = new StringBuffer();

System.out.println(sb.capacity()); // 16

Default capacity is 16 characters.

7. length()​

Returns the number of characters in the string.

StringBuffer sb = new StringBuffer("Java");

System.out.println(sb.length()); //4

8. charAt()​

Returns the character at a specified index.

StringBuffer sb = new StringBuffer("Java");

System.out.println(sb.charAt(2)); // v

9. setCharAt()​

Changes the character at a specified index.

StringBuffer sb = new StringBuffer("Java");

sb.setCharAt(0, 'R');

System.out.println(sb); // Rava

10. toString()​

Converts StringBuffer to String.

StringBuffer sb = new StringBuffer("Java");

String str = sb.toString();

System.out.println(str); // Java

Summary​

  • StringBuffer is mutable
  • It is thread-safe (synchronized)
  • Used in multi-threaded environments