String in Java

In Java, A String is an object that represents a sequence of characters. Unlike some other programming languages where strings are treated as primitive data types, in Java, strings are objects of the String class.
Strings in Java are immutable, meaning their values cannot be changed after they are created. This means that operations such as concatenation or substring creation will result in the creation of new string objects rather than modifying the original string.

In the below PDF we discuss about String in Java  in detail in simple language, Hope this will help in better understanding.

Creating Strings:

There are several ways to create strings in Java:

1. String literals: String literals are created by enclosing text within double quotes. For example:

String message = "Hello, world!";

2. Using the new keyword: Strings can also be created using the new keyword, though this is less common:

String message = new String("Hello, world!");


Below is an example of a String in Java:

// Java Program to demonstrate
// String
public class StringExample {

// Main Function
public static void main(String args[])
String str = new String("Topperworld");
// creating Java string by new keyword
// this statement create two object i.e
// first the object is created in heap
// memory area and second the object is
// created in String constant pool.

//output = Topperworld

1. StringBuffer:

The StringBuffer class represents mutable strings. Unlike String, StringBuffer objects can be modified after creation. It provides methods for appending, inserting, deleting, replacing, and reversing characters in the string. StringBuffer is thread-safe, meaning it can be safely used in multi-threaded applications.

StringBuffer stringBuffer = new StringBuffer();
stringBuffer.append(" ");

2. StringBuilder:

The StringBuilder class is similar to StringBuffer but is not thread-safe. It provides methods for string manipulation like StringBuffer but does not incur the synchronization overhead. StringBuilder is preferred in single-threaded environments or scenarios where thread safety is not a concern.

StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append(" ");

Common String Operations:

Java provides a rich set of methods for performing various operations on strings. Some of the most commonly used string operations include:

  • Concatenation: Combining two strings together using the + operator or the concat() method.
  • Length: Retrieving the length of a string using the length() method.
  • Substring: Extracting a portion of a string using the substring() method.
  • Comparison: Comparing strings for equality or lexicographical order using methods like equals(), equalsIgnoreCase(), compareTo(), etc.
  • Searching: Searching for specific substrings within a string using methods like indexOf(), lastIndexOf(), contains(), etc.
  • Modification: Converting cases, replacing characters, trimming whitespaces, etc., using various methods provided by the String class.


In Conclusion, Strings are essential for representing and manipulating textual data in Java programs. Understanding how to work with strings effectively is crucial for developing Java applications that handle text processing, user input, output formatting, and more.

Must Read: Array In Java

Related Question

A String in Java is a sequence of characters, such as letters, digits, and symbols, enclosed within double quotes (” “).

You declare a String variable by specifying the data type String followed by the variable name and optionally assigning it a value, like this: String myString = “Hello”;.

Yes, you can concatenate Strings in Java using the + operator or the concat() method.

You compare two Strings in Java using the equals() method for content comparison or == for reference comparison.

You can split a String into substrings using the split() method, which divides a String into an array of substrings based on a specified delimiter.


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