Java String lastIndexOf()

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In the last tutorial we discussed indexOf() method. In this tutorial we will discuss lastIndexOf() method which is used for finding out the index of last occurrence of a char/sub-string in a particular String.

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

Internal Implementation

public int lastIndexOf(int ch) 
   {  
       return lastIndexOf(ch, value.length - 1);  
   }

  1. lastIndexOf() : This method returns the index of the last occurrence of the character in the character sequence .

    
Syntax:
int lastIndexOf(int ch)
Parameters:
ch : a character.
Return Value:
This method returns the index.

  2. lastIndexOf(int ch, int beg) : This method returns the index of the last occurrence of the character in the character sequence represented by this object that is less than or equal to beg, or -1 if the character does not occur before that point.

    
Syntax:
public int lastIndexOf(int ch, int beg)
Parameters:
ch : a character.
beg : the index to start the search from.
Returned Value:
This method returns the index.

  3. lastIndexOf(String str) : This method accepts a String as an argument, if the string argument occurs one or more times as a substring within this object, then it returns the index of the first character of the last such substring is returned. If it does not occur as a substring, -1 is returned.

    
Syntax:
public int lastIndexOf(String str)
Parameters:
str : a string.
Returned Value:
This method returns the index.

  4. lastIndexOf(String str, int beg) : This method returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.

    
Syntax:
public int lastIndexOf(String str, int beg)
Parameters
beg : the index to start the search from.
str : a string.
Return Value
This method returns the index.

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

Returns

last index of the string

Example of lastIndexOf() method

public class Test
{
public static void main(String args[]) 
{
String str1 = new String("This is a BeginnersBook tutorial");
String str2 = new String("Beginners");
String str3 = new String("Book");
String str4 = new String("Books");
System.out.println("Last 'B' in str1: "+str1.lastIndexOf('B'));
System.out.println("Last 'B' in str1 whose index<=15:"+str1.lastIndexOf('B', 15));
System.out.println("Last 'B' in str1 whose index<=30:"+str1.lastIndexOf('B', 30));
System.out.println("Last occurrence of str2 in str1:"+str1.lastIndexOf(str2));
System.out.println("Last occurrence of str2 in str1 before 15:"+str1.lastIndexOf(str2, 15));
System.out.println("Last occurrence of str3 in str1:"+str1.lastIndexOf(str3));
System.out.println("Last occurrence of str4 in str1"+str1.lastIndexOf(str4));
System.out.println("Last occurrence of 'is' in str1:"+str1.lastIndexOf("is"));
System.out.println("Last occurrence of 'is' in str1 before 4:"+str1.lastIndexOf("is", 4));
}
}


Output:

Last 'B' in str1: 19
Last 'B' in str1 whose index<=15:10
Last 'B' in str1 whose index<=30:19
Last occurrence of str2 in str1:10
Last occurrence of str2 in str1 before 15:10
Last occurrence of str3 in str1:19
Last occurrence of str4 in str1-1
Last occurrence of 'is' in str1:5
Last occurrence of 'is' in str1 before 4:2
Java String lastIndexOf() method example

public class Test
{  
public static void main(String args[])
{  
String s1="this is index of example";
//there are 3 'i' characters in this sentence  
int index1=s1.lastIndexOf('i');
//returns last index of 's' char value  
System.out.println(index1);//8  
}
}


Output:

8
Java String lastIndexOf(int ch, int fromIndex) Method Example

Here, we are finding last index from the string by specifying fromIndex


public class Test 
{  
    public static void main(String[] args) 
   {  
        String str = "This is index of example";  
        int index = str.lastIndexOf('s',5);  
        System.out.println(index);        
    }  
}


Output:

3
Java String lastIndexOf(String substring) Method Example

It returns the last index of the substring.


public class Test
{  
    public static void main(String[] args) 
   {           
        String str = "This is last index of example";  
        int index = str.lastIndexOf("last");  
        System.out.println(index);        
    }  
}


Output:

8
Java String lastIndexOf(String substring, int fromIndex) Method Example

It returns the last index of the substring from the fromIndex.


public class Test
{  
    public static void main(String[] args) 
   {           
        String str = "This is last index of example";  
        int index = str.lastIndexOf("of", 30);  
        System.out.println(index);  
        index = str.lastIndexOf("of", 10);  
        System.out.println(index); // -1, if not found        
    }  
}


Output:

19
-1



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