Introduction

• The StringBuffer class in Java represents a sequence of characters that can be modified after creation (mutable strings).
• It was introduced in JDK 1.0 version.
• StringBuffer class is present in java.lang package.
• Syntax :-

  package java.lang;
  
  public final class StringBuffer extends AbstractStringBuilder implements Serializable, CharSequence
  {
      // Fields
      // Constructors
      // Methods
  }

• Unlike String, StringBuffer objects are mutable, meaning you can change their content without creating a new object.

  StringBuffer sb = new StringBuffer("Deepak");
  sb.append(" Panwar");     // Modifies the same object
  System.out.println(sb);  // Output: Deepak Panwar

Methods of StringBuffer Class:

• Below are some common and important methods of StringBuffer class with examples:

StringBuffer sb = new StringBuffer("Hello");
sb.append(" World");
System.out.println(sb);

StringBuffer sb = new StringBuffer("Hello World");
sb.insert(6, "Java ");
System.out.println(sb);

StringBuffer sb = new StringBuffer("Hello World");
sb.replace(6, 11, "Java");
System.out.println(sb);

StringBuffer sb = new StringBuffer("Hello Java");
sb.delete(5, 10);
System.out.println(sb);

StringBuffer sb = new StringBuffer("Hello");
sb.reverse();
System.out.println(sb);

StringBuffer sb = new StringBuffer("Hello");
System.out.println(sb.charAt(1));

StringBuffer sb = new StringBuffer("Hello");
sb.setCharAt(0, 'Y');
System.out.println(sb);

StringBuffer sb = new StringBuffer("Hello");
System.out.println(sb.length());

StringBuffer sb = new StringBuffer("Hello");
System.out.println(sb.capacity());

StringBuffer sb = new StringBuffer("Hello World");
sb.setLength(5);
System.out.println(sb);

StringBuffer sb = new StringBuffer("Hello World");
System.out.println(sb.substring(0, 5));

Properties of StringBuffer Class:

1. Mutable:
   • StringBuffer objects are mutable, meaning their content can be changed after creation without creating a new object.
2. Stored in Heap Memory:
   • StringBuffer objects are stored in heap memory, unlike string literals which are stored in the String Constant Pool (SCP).
3. Thread-Safe (Synchronized):
   • StringBuffer methods are synchronized, making it safe to use in multi-threaded environments.
4. Dynamic Resizing:
   • StringBuffer automatically increases its capacity as more characters are added, improving performance during multiple modifications.
5. Unicode Support:
   • StringBuffer stores text as UTF-16 encoded Unicode characters, supporting multiple languages and symbols.