Java ArrayList contains() Method example

ArrayList contains() method is used for checking the specified element existence in the given list.

public boolean contains(Object element)

It returns true if the specified element is found in the list else it gives false.

Example

Here we are testing the contains() method on two arraylists, First we have created an ArrayList of Strings, added some elements to it and then we are checking whether certain specific strings exist in this arraylist using the contains().

In the second part of this program we have an ArrayList of Integers so here we are performing the test on some numbers. The example is pretty self explanatory. I have explained the output at the end of the program.

package beginnersbook.com;
import java.util.ArrayList;
public class ContainsExample {
   public static void main(String[] args) {

      ArrayList<String> al = new ArrayList<String>();
      al.add("pen");
      al.add("pencil");
      al.add("ink");
      al.add("notebook");

      System.out.println("ArrayList contains the string 'ink pen': "
                                           +al.contains("ink pen"));
      System.out.println("ArrayList contains the string 'pen': "
                                             +al.contains("pen"));
      System.out.println("ArrayList contains the string 'pencil': "
                                          +al.contains("pencil"));
      System.out.println("ArrayList contains the string 'book': "
                                           +al.contains("book"));

      ArrayList<Integer> al2 = new ArrayList<Integer>();
      al2.add(1);
      al2.add(99);
      al2.add(56);
      al2.add(13);
      al2.add(44);
      al2.add(6);

      System.out.println("'1' is present in arraylist: "+al2.contains(1));
      System.out.println("'55' is present in arraylist: "+al2.contains(55));
      System.out.println("'44' is there in arraylist: "+al2.contains(44));
      System.out.println("'7' is there in arraylist: "+al2.contains(7));
   }
}

Output:

ArrayList contains the string 'ink pen': false
ArrayList contains the string 'pen': true
ArrayList contains the string 'pencil': true
ArrayList contains the string 'book': false
'1' is present in arraylist: true
'55' is present in arraylist: false
'44' is there in arraylist: true
'7' is there in arraylist: false

You can observe the output of the above program, since the element pen and pencil were present in the ArrayList al, contains() method returned true for them and the elements ink pen and book were not present in the Arraylist al, method returned false for them.

Similarly for the integer Arraylist al2, the contains() method returned true for numbers 1 and 44 as they exist in the arraylist and false for numbers 55 and 7 as they do not present in the arraylist.

Reference:

Javadoc