ArrayList search

In this chapter you will learn:

How to get object for index
If an ArrayList contains a certain object

Get object for index

int indexOf(Object o) Returns the index of the first occurrence, or -1 if this list does not contain the element. int lastIndexOf(Object o) Returns the index of the last occurrence, or -1 if this list does not contain the element.

import java.util.ArrayList;
//from   j a va 2  s .co  m
public class Main {
  public static void main(String args[]) {
    ArrayList<String> al = new ArrayList<String>();

    al.add("C");
    al.add("java2s.com");
    al.add("D");
    al.add("F");
    al.add(1, "java2s.com");

    System.out.println(al);
    System.out.println(al.indexOf("java2s.com"));
    System.out.println(al.lastIndexOf("java2s.com"));

  }

}

The output:

If contain a certain object

boolean contains(Object o) Returns true if this list contains the specified element.

import java.util.ArrayList;
import java.util.List;
/*from   j a va2s.co  m*/
public class Main {
  public static void main(String args[]) {
    ArrayList<String> al = new ArrayList<String>();

    al.add("C");
    al.add("A");
    al.add("E");
    al.add("java2s.com");
    al.add("D");
    al.add("F");
    al.add(1, "java2s.com");

    System.out.println(al);

    
    System.out.println(al.contains("java2s.com"));

  }

}