Java String indexOf

The java string indexOf() method returns index of given character value or substring. If it is not found, it returns -1. The index counter starts from zero.

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Signature

There are 4 types of indexOf method in java. The signature of indexOf methods are given below:

No.	Method	Description
1	int indexOf(int ch)	returns index position for the given char value
2	int indexOf(int ch, int fromIndex)	returns index position for the given char value and from index
3	int indexOf(String substring)	returns index position for the given substring
4	int indexOf(String substring, int fromIndex)	returns index position for the given substring and from index

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Parameters

ch: char value i.e. a single character e.g. 'a'

fromIndex: index position from where index of the char value or substring is retured

substring: substring to be searched in this string

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Returns

index of the string

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Java String indexOf() method example

1. public class IndexOfExample{  
2. public static void main(String args[]){  
3. String s1="this is index of example";  
4. //passing substring  
5. int index1=s1.indexOf("is");//returns the index of is substring  
6. int index2=s1.indexOf("index");//returns the index of index substring  
7. System.out.println(index1+"  "+index2);//2 8  
8.   
9. //passing substring with from index  
10. int index3=s1.indexOf("is",4);//returns the index of is substring after 4th index  
11. System.out.println(index3);//5 i.e. the index of another is  
12.   
13. //passing char value  
14. int index4=s1.indexOf('s');//returns the index of s char value  
15. System.out.println(index4);//3  
16. }}  

Output

2  8
5
3