String Buffer/String Builder in Java

What is String Buffer:

• StringBuffer is a mutable and thread-safe class used to modify strings.
• String Buffer is a child of the CharSequence interface
• StringBuffer is a **mutable class **in Java. When we perform operations like append or modify, it updates the same object instead of creating a new one, which improves performance.
• StringBuffer is synchronised/THREAD-SAFE (Multiple threads can't access it simultaneously)

How to create a StringBuffer Object:

• By using only new Keyword

StringBuffer s= new StringBuffer("Java");

Object will be created in heap memory, and the reference variable is pointing to it.

StringBuffer Methods:

1. append() → Add data Adds text at the end

StringBuffer sb = new StringBuffer("Java");
sb.append(" World");

System.out.println(sb);
O/P:Java World

1. insert() → Insert at specific position Adds text at a given index

StringBuffer sb = new StringBuffer("Java");
sb.insert(2, "XX");

System.out.println(sb);
o/P: JaXXva

1. replace() → Replace part of string Replaces characters between indexes

StringBuffer sb = new StringBuffer("Java");
sb.replace(1, 3, "XX");

System.out.println(sb);
O/P: JXXa

1. delete() → Delete characters Removes characters between indexes

StringBuffer sb = new StringBuffer("Java");
sb.delete(1, 3);

System.out.println(sb);
O/P: Ja

1. reverse() → Reverse the string

StringBuffer sb = new StringBuffer("Java");
sb.reverse();

System.out.println(sb);
O/P: avaJ

1. capacity() → Check memory capacity Default capacity = 16 + string length

StringBuffer sb = new StringBuffer("Java");
System.out.println(sb.capacity());
O/P: 20

1. length() → Length of string

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

1. charAt() → Get character

System.out.println(sb.charAt(1));

1. setCharAt() → Change character

StringBuffer sb = new StringBuffer("Java");
sb.setCharAt(0, 'M');

System.out.println(sb);
O/P: Mava

1. ensureCapacity() → Increase capacity

sb.ensureCapacity(50);
Ensures buffer can hold at least 50 characters

What is StringBuilder:

• String Builder is a child of the CharSequence interface
• String Builder is a MUTABLE object
• StringBuilder is NON-Synchronised/NOT THREAD-SAFE(Multiple threads can access)

Methods are the same as StringBuffer