arraylist indexOf, lastIndexOf example

package com.concretepage;

import java.util.ArrayList;

public class TestOneFour {
public static void main(String[] args) {
    ArrayList<Object> ref = new ArrayList<>();
    ref.add(1);ref.add(2);ref.add("Three");ref.add(4);ref.add(5);
    ref.add(6);ref.add("Seven");ref.add("Three");ref.add("Three");ref.add(8);ref.add(9);
    System.out.println(ref.indexOf("Three"));
    System.out.println(ref.lastIndexOf("Three"));
    System.out.println(ref.indexOf("Seven"));
}
}