What is the lastIndexOf() method in Java?

import java.util.*;

class Program {
    public static void main( String args[] ) {
      String str = "educative";
      int lastIndex = str.lastIndexOf('e');
      System.out.println("The last index of this character is: " + lastIndex);
    }
}

import java.util.*;
class Program {
    public static void main( String args[] ) {
      String str = "Welcome to educative.";
      int lastIndex = str.lastIndexOf("to");
      System.out.println("The last index of this sub-string is: " + lastIndex);
    }
}

import java.util.*;
class Program {
    public static void main( String args[] ) {
      String str = "welcome to educative!";
      // The string is only searched backwards from the 9th char.
      int lastIndex = str.lastIndexOf('e', 9);
      System.out.println("The last index of this character is: " + lastIndex);
      // The string is only searched backwards from the 14th char.
      lastIndex = str.lastIndexOf('e', 14);
      System.out.println("The last index of this character is: " + lastIndex);
    }
}