Use StringBuffer Instead of String in Java

In Java, both String and StringBuffer classes are used to represent sequences of characters. However, the String class is immutable, which means once a String object is created, its value cannot be changed, while the StringBuffer class is mutable. It allows us to modify the contents of the string without creating a new object.

In this article, we will discuss why we should use the StringBuffer class instead of String in Java.

Why Use StringBuffer Instead of String?

A few reasons why StringBuffer is often preferred over String is given below:

• A StringBuffer is thread-safe because its methods are synchronized. We can use it when multiple threads are modifying the same buffer.
• Unlike a String class, the StringBuffer class represents a mutable sequence of characters. Therefore, all modification operations like appending, inserting, or deleting happen on the same object.
• We can also use StringBuffer when repeated string concatenations inside loops are required. It provides better performance since it avoids creating multiple intermediate String objects.
• The StringBuffer class offers a different set of methods than the String class, all of which operate directly on the buffer that contains the string. Some of its methods are: append(), insert(), replace(), and delete().
• A StringBuffer can be defined simply by the use of the new operator and passing the string value inside a StringBuffer constructor.

Example: Disadvantages of String

The System.identityHashCode() returns a unique memory reference for the String object. If the hash codes before and after modification do not match, that means a new String object was created instead of modifying the original one. In the following example, we are checking whether the same String is being modified or not.

public class StringDemo {
   public static void main(String[] args) {
      String str = "Java Tutorials Point"; 
      System.out.println("Original String: " + str);
      System.out.println("Original String HashCode: " + System.identityHashCode(str));
      // Modify the string
      str = "Tutorialspoint Java";  
      System.out.println("New String: " + str);
      System.out.println("New String HashCode: " + System.identityHashCode(str));
   }
}

On running the above Java program, you will get two different HashCodes as shown below:

Original String: Java Tutorials Point
Original String HashCode: 2038148563
New String: Tutorialspoint Java
New String HashCode: 2008966511

Example: Using StringBuffer in Java

In the below Java program, we initially created an instance of the StringBuffer class and appended a string to the StringBuffer class using the append() method. It will modify the same object rather than creating a new one.

public class StringBufferDemo {
   public static void main(String arg[]){
      StringBuffer sb = new StringBuffer();
      sb.append("Java Tutorials Point");
      System.out.println(sb);
   }
}

Output of the above code is as follows:

Java Tutorials Point