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AbstractList lastIndexOf() method in Java with Examples

  • Last Updated : 21 Nov, 2019

The lastIndexOf() method of java.util.AbstractList class is used to return the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the highest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.

Syntax:

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public int lastIndexOf(Object o)

Parameters: This method takes Object o as a parameter which is the element to search for.

Returns Value: This method returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.



Exception: This method throws NullPointerException if the specified element is null and this list does not permit null elements.

Below are the examples to illustrate the lastIndexOf() method.

Example 1:




// Java program to demonstrate
// lastIndexOf() method
// for String value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
        try {
  
            // Creating object of AbstractList<String>
            AbstractList<String>
                arrlist1 = new ArrayList<String>();
  
            // Populating arrlist1
            arrlist1.add("A");
            arrlist1.add("B");
            arrlist1.add("A");
            arrlist1.add("B");
            arrlist1.add("E");
  
            // print arrlist1
            System.out.println("ArrayList : "
                               + arrlist1);
  
            // getting the index of last occurrence
            // using lastIndexOf() method
            int lastindex = arrlist1.lastIndexOf("A");
  
            // printing the Index
            System.out.println("Last index of A : "
                               + lastindex);
        }
  
        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}
Output:
ArrayList : [A, B, A, B, E]
Last index of A : 2

Example 2:




// Java program to demonstrate
// lastIndexOf() method
// for NullPointerException
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            // Creating object of AbstractList<String>
            AbstractList<String> arrlist1 = null;
  
            // print arrlist1
            System.out.println("ArrayList : "
                               + arrlist1);
  
            // getting the index of last occurrence
            // using lastIndexOf() method
            System.out.println("\nTrying to get"
                               + " the index from"
                               + " null ArrayList");
            int lastindex = arrlist1.lastIndexOf("B");
  
            // printing the Index
            System.out.println("Last index of B : "
                               + lastindex);
        }
  
        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}
Output:
ArrayList : null

Trying to get the index from null ArrayList
Exception thrown : java.lang.NullPointerException



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