Everything you need to know about finding index of item in list with java

In this article, we will discuss finding the index of the list. List<T> is an interface in java that provides many helpful methods for operating items of lists. The IndexOf() method returns the index of an item if the item found else it return -1.

There are two methods we can use for finding index:

• indexOf(Object obj):- This method returns the first index of an item if it is present in the list.

FindIndex.java

import java.util.Arrays;
import java.util.List;

public class FindIndex {
    public static void main(String[] args) {
        List<String> list = Arrays.asList(
        	"Are", "you", "programmer","?", "you", "are", "awesome!."
        );
        String findMe = "you";
        System.out.println("Index of "+ findMe +": " +list.lastIndexOf(findMe));
    }
}        

Output:

• lastIndexOf(Object obj):- This method returns the first index from the of an item if it is present in the list.

FindIndex.java

import java.util.Arrays;
import java.util.List;

public class FindIndex {
    public static void main(String[] args) {
        List<String> list = Arrays.asList(
        	"Are", "you", "programmer","?", "you", "are", "awesome!."
        );
        String findMe = "you";
        System.out.println("Last Index of "+ findMe +": " +list.lastIndexOf(findMe));
    }
}

       

Output: