>> indexOf(), lastIndexOf to find the position of a letter/char in a string

               

// indexOf() : to know the position of a particular letter/char or word in the given string . And it gives the first occurance of the letter/char in the string. 
              

// index starts from 0

String word = "success";

             //0123456-> "s" is index 0 , "u" is index 1 and so on.          

               

// for example         

System.out.println("The index of u is : " +word.indexOf("u"));

               

//when two letter are together, the index of first letter is returned.

System.out.println("The index of c is : " +word.indexOf("c"));         

               

String word1="success ful";

// space are considered as a character.

System.out.println("The index of f is : " +word1.indexOf("f"));

               

//indexOf() will also take char datatype
char txt = 'c';
System.out.println("The index of c when input is provided as char : " +word1.indexOf(txt ));
//OR // let's give the input directly as char as below for f :

System.out.println("The index of f when input is provided as char : " +word1.indexOf('f'));

               

// can also find out the position of string in the given string

System.out.println("The index of ces is : " +word1.indexOf("ces"));

               

// when the given letter is not present in the word, it returns -1

System.out.println("The index of a is : " +word1.indexOf("a")); // letter

System.out.println("The index of car is : " +word1.indexOf("car")); // string

// lastIndexOf() :To know the last occurance of the letter/char in the given string.
// first occurance

System.out.println("The first occurance of u is : " +word1.indexOf("u")); 

//last occurance

System.out.println("The last occurance of u is : " +word1.lastIndexOf("u")); 

               

      

Answer:

The index of u is : 1

The index of c is : 2

The index of f is : 8
The index of c when input is provided as char : 2

The index of f when input is provided as char : 8

The index of ces is : 3

The index of a is : -1

The index of car is : -1

The first occurance of u is : 1

The last occurance of u is : 9

//occurance after given text/index

String word = "This world is beautiful.";

             

System.out.println("In normal it displays 1st occurance of i as : "+word.indexOf("i"));

             

System.out.println("Occurance of i after 5th index as : "+word.indexOf("i", 5)); 

Answer:

In normal it displays 1st occurance of i as : 2

Occurance of i after 5th index as : 11

//Another way

             

String test = new String("This world is beautiful. Fish lives in Sea.");

             

System.out.println("In normal it displays 1st occurance of is as : "+test.indexOf("is"));

             

System.out.println("Occurance of is after 15th index as : "+test.indexOf("is", 15));

Answer :

In normal it displays 1st occurance of is as : 2

Occurance of is after 15th index as : 26

//OR

             

String test = new String("This world is beautiful. Fish lives in Sea.");

String word = new String("is");

             

System.out.println("In normal it displays 1st occurance of is as : "+test.indexOf(word));

             

System.out.println("Occurance of is after 15th index as : "+test.indexOf(word, 15));    

Answer :

In normal it displays 1st occurance of is as : 2

Occurance of is after 15th index as : 26