Java String indexOf() Method
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 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'));
}
}
Output
Found 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.
Table of Content
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 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));
}
}
Output
Found 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 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));
}
}
Output
Found 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 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));
}
}
Output
Found geeks(after 14th index) starting at position: 19
