Java String indexOf() Method
Last Updated : 19 Nov, 2024
In Java, the String indexOf() method returns the position of the first occurrence of the specified character or string in a specified string. In this article, we will learn various ways to use indexOf() in Java.
Example:
Below is the simplest way that returns the index of the first occurrence of a specified character in a string, or -1 if the character does not occur.
Java // Java code to demonstrate the working of String indexOf() // using indexOf(char ch) public class Index1 { public static void main(String args[]) { String s = new String("Welcome to geeksforgeeks"); System.out.print("Found g first at position: "); System.out.println(s.indexOf('g')); } } OutputFound g first at position: 11
Explanation:
In the above example, it finds the first occurrence of the character g in the string "Welcome to geeksforgeeks" and prints its index i.e. 11.
Different Variants of indexOf() Method in Java
There are 3 variants of the indexOf() method are mentioned below:
1. indexOf(char ch, int strt)
This method returns the index of the first occurrence of the specified character by starting the search at the specified index.
Example:
Java // Java code to demonstrate the working of String indexOf(char ch, int strt) public class Index2 { public static void main(String args[]) { String s = new String("Welcome to geeksforgeeks"); System.out.print( "Found g after 13th index at position: "); System.out.println(s.indexOf('g', 13)); } } OutputFound g after 13th index at position: 19
2. indexOf(String str)
This method returns the index of the first occurrence of the specified substring in the string.
Example:
Java // Java code to demonstrate the working of String indexOf(String str) public class Index3 { public static void main(String args[]) { String s = new String("Welcome to geeksforgeeks"); // Initializing search string String s1 = new String("geeks"); // print the index of initial character of Substring System.out.print( "Found geeks starting at position: "); System.out.print(s.indexOf(s1)); } } OutputFound geeks starting at position: 11
3. indexOf(String str, int strt)
This method returns the index of the first occurrence of the specified substring by starting the search at the specified index.
Example:
Java // Java code to demonstrate the working of String indexOf(String str, int strt) public class Index4 { public static void main(String args[]) { String s = new String("Welcome to geeksforgeeks"); // Initializing search string String s1 = new String("geeks"); // print the index of initial character // of Substring after 14th position System.out.print( "Found geeks(after 14th index) starting at position: "); System.out.print(s.indexOf(s1, 14)); } } OutputFound geeks(after 14th index) starting at position: 19