Strings in Java

In Java, a string is a sequence of characters. Strings are used to represent text in programs, and are one of the most common data types in Java.

Strings are represented by the “String” class in Java. Here’s an example of how to create a string in Java:

String message = "Hello, world!";

In this example, the variable “message” is a string containing the text “Hello, world!”. The string is created using double quotes, and is assigned to the variable using the “=” operator.

Strings in Java are immutable, which means that once a string is created, its value cannot be changed. However, you can create new strings by concatenating existing strings or by using methods to manipulate the contents of a string.

Here’s an example of how to concatenate strings in Java:

String name = "John";
String greeting = "Hello, " + name + "!";
System.out.println(greeting);

In this example, two strings are concatenated to create a new string containing the text “Hello, John!”. The “+” operator is used to concatenate the strings.

Java provides a number of built-in methods for working with strings, such as “length”, “charAt”, “substring”, and “indexOf”. Here are a few examples:

In these examples, the “length” method returns the number of characters in the string, the “charAt” method returns the character at a specific index, the “substring” method returns a new string containing a portion of the original string, and the “indexOf” method returns the index of a specific substring within the string.

Strings are used in many different ways in Java, such as displaying output to the user, reading input from the user, storing data in memory, and communicating with external systems over a network. Understanding how to work with strings is an important part of programming in Java.