What is the difference between String and StringBuilder in Java?

Introduction

In this shot, we will discuss the difference between String and StringBuilder in Java. Before moving ahead, let’s look at the table of differences between String and StringBuilder.

String vs. StringBuilder


Parameter


String


StringBuilder



Storage

String pool


Heap memory


Mutability

Immutable


Mutable

Performance

Slower than StringBuilder

Faster than String


Usage in threaded

environment

Not used in a threaded environment

Used in a single threaded environment


Syntax

String variable=”String”;


String variable= new String(“String”);

StringBuilder variable= new StringBuilder(“String”);

Solution approach

  • We can approach comparing String and StringBuilder by creating an instance of the String and StringBuilder classes.

  • We will perform concatenation of String instances with the += operator and concatenation of StringBuilder instances with the .append() method.

append() is used to add the specified string with the string passed as an argument.

This is how we will compare the performance of String and StringBuilder.

Code

Let’s look at the code snippet below.

class Main {
    public static void main(String[] args) {
        String s = new String("This ");
        
        s+="is ";
        s+="String object";
        
        System.out.println(s);
        StringBuilder sb = new StringBuilder("This ");
        
        sb.append("is ");
        sb.append("StringBuilder object");
        
        System.out.println(sb);
    }
}

Explanation

  • In line 1, we create a Main class with the main() function.

  • In line 3, we initialize the String class instance and concatenate it with the other strings in lines 5 and 6.

  • Each time the code performs a string operation (+=), a new string is created in the string pool.

  • In line 8, we display the concatenated string.

  • In line 10, we initialize an instance of the StringBuilder class.

  • The StringBuilder object will alter 2 times in lines 12 and 13. Each time the code attempts a StringBuilder operation without creating a new object, i.e., using the StringBuilder class can boost performance when concatenating many strings together in a loop.

  • In line 15, we display the concatenated string.

In this way, we analyzed the difference between String and StringBuilder in Java.

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