Strings
String
In Java, a String is a sequence of characters used to store text such as words, sentences, or any combination of letters, numbers, and symbols.
A String is one of the most commonly used data types in Java and is part of the java.lang package.
A String variable contains a collection of characters surrounded by double quotes (" ").
Strings are used for storing text in Java programs.
Example
public class Main {
public static void main(String[] args) {
// Creating a String variable to store text
String greeting = "Hello";
// Printing the value of String variable on screen
System.out.println(greeting);
}
}
String Concatenation
String concatenation in Java means joining two or more strings together to form a single string.
It is commonly used to combine text, variables, and output messages in Java programs.
The + operator can be used between strings to combine them. This is called concatenation.
Example
public class Main {
public static void main(String[] args) {
// Creating first string with a space at the end
String firstName = "John ";
// Creating second string
String lastName = "Doe";
// Using concat() method to join both strings
System.out.println(firstName.concat(lastName));
}
}
String Methods
String methods in Java are built-in functions used to perform different operations on strings such as finding length, changing case, comparing, searching, and modifying text.
String Methods
- length() → returns the number of characters in a string
- toUpperCase() → converts string to uppercase
- toLowerCase() → converts string to lowercase
- trim() → removes extra spaces from beginning and end
- charAt() → returns character at a specific position
- indexOf() → finds the position of a character or word
- substring() → extracts part of a string
- equals() → compares two strings
- equalsIgnoreCase() → compares strings ignoring case
- contains() → checks if string contains specific text
- replace() → replaces characters or words
- startsWith() → checks starting characters
- endsWith() → checks ending characters
- isEmpty() → checks if string is empty
- concat() → joins two strings