Skip to main content

String Overview & Creation

What is a String?​

A String in Java is a sequence of characters used to represent text.

In Java, strings are objects of the String class located in the java.lang package.

String = Immutable sequence of characters

Once a string object is created, its value cannot be changed.

Key Characteristics of String​

  • Strings are immutable (cannot be modified after creation)
  • Stored in the String Constant Pool (SCP)
  • Frequently used for handling text data
  • Part of the java.lang package (no import needed)

Ways to Create a String

There are two main ways to create a String in Java.

  1. Using String Literal
  2. Using the new keyword (Constructor)

1. Creating String Using Literal​

String s = "Hello";

How it works​

  • The string "Hello" is stored in the String Constant Pool
  • If the same string already exists, Java reuses the existing object

Example:

String s1 = "Java";
String s2 = "Java";

System.out.println(s1 == s2); // true

Both variables reference the same object in the String Pool.

2. Creating String Using new Keyword​

String s = new String("Hello");

How it works​

  • Creates a new object in heap memory
  • Even if "Hello" exists in the String Pool, a new object is created

Example:

String s1 = new String("Java");
String s2 = new String("Java");

System.out.println(s1 == s2); // false

Because both objects are stored in different memory locations.

String Creation Using Character Array

Strings can also be created from a character array.

char[] ch = {'J','a','v','a'};

String s = new String(ch);

System.out.println(s); // Java

String Creation Using StringBuilder or StringBuffer

A string can be created from StringBuilder or StringBuffer objects.

StringBuilder sb = new StringBuilder("Hello");

String s = sb.toString();

System.out.println(s);

String Memory Concept

When a string is created using a literal, it goes to the String Pool.

Example:

String s1 = "Java";
String s2 = "Java";

Only one object exists, both variables reference it.

When to Use Each Creation Method

MethodUsage
String LiteralPreferred for memory efficiency
new String()Creates a new object explicitly
char[]Useful when converting character arrays
StringBuilder/StringBufferWhen building dynamic strings

Summary

  • String represents text in Java.
  • Strings are immutable objects.
  • They can be created using:
    • String literals
    • new keyword
    • character arrays
    • StringBuilder / StringBuffer
  • Literals are stored in the String Constant Pool to save memory.