Introduction

• The StringBuilder class in Java represents a sequence of characters that can be modified after creation (mutable strings).
• StringBuilder is non-synchronized, which means it is not thread-safe but offers better performance than StringBuffer in single-threaded applications.
• It was introduced in JDK 1.5 as a faster alternative to StringBuffer.
• StringBuilder class is present in java.lang package.
• Syntax :-

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

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

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

Methods of StringBuilder Class:

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

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

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

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

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

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

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

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

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

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

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

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

Properties of StringBuilder Class:

1. Mutable:
   • StringBuilder objects are mutable, meaning their content can be changed after creation without creating a new object.
2. Stored in Heap Memory:
   • StringBuilder objects are stored in heap memory, unlike string literals which are stored in the String Constant Pool (SCP).
3. Non-Synchronized (Not Thread-Safe):
   • StringBuilder methods are not synchronized, so it is not safe in multi-threaded environments. However, this makes it faster and more efficient than StringBuffer in single-threaded applications.
4. Dynamic Resizing:
   • StringBuilder automatically increases its capacity as more characters are added, reducing overhead of frequent object creation.
5. Unicode Support:
   • StringBuilder stores text as UTF-16 encoded Unicode characters, supporting multiple languages and symbols.