Java Deque contains() Method

The contains() method of Java Deque Interface returns true if the deque contains the specified element.

Specified by:

contains in interface Collection<E>

Syntax:

Parameter:

The above method consists of only one parameter:

a.) The element 'o' which is already present in the deque and is tested.

Return:

The above method returns a Boolean value, i.e., true if the specified element is already present in the deque .

Throw:

ClassCastException- If the class of the given element is incompatible with the deque.

NullPointerException- If the specified element is a null and the deque does not allow the null elements.

Example 1

import java.util.ArrayDeque;
import java.util.Deque;
public class JavaDequecontainsExample1 {
   public static void main(String[] args) {
	Deque<Float> deque = new ArrayDeque<>();
	System.out.println("The list of the elements is given as : ");
	deque.add(45f);
	deque.add(31f);
	deque.add(456f);
	deque.add(29f);
  System.out.println("The final result of the deque is given as : "+deque);
	 boolean b1 = deque.contains(45f);
	 if(b1==true)
	 {
		 System.out.println("The first element is in the list.");
	 }
	 else
	 {
		 System.out.println("The first element is not in the list.");
	 } 
	 boolean b2 = deque.contains(100f);
	 if(b2==true)
	 {
		 System.out.println("The second element is in the list.");
	 }
	 else
	 {
		 System.out.println("The second element is not in the list.");
	 }
   }
}

Test it Now

Output:

The list of the elements is given as : 
The final result of the deque is given as : [45.0, 31.0, 456.0, 29.0]
The first element is in the list.
The second element is not in the list.

Example 2

import java.util.ArrayDeque;
import java.util.Deque;
public class JavaDequecontainsExample2 {
   public static void main(String[] args) {
	Deque<Character> deque = new ArrayDeque<>();
	System.out.println("The list of the elements is given as : ");
	deque.add('A');
	deque.add('J');
	deque.add('M');
	deque.add('O');
  System.out.println("The final result of the deque is given as : "+deque);
	 boolean b1 = deque.contains('Z');
	 if(b1==true)
	 {
		 System.out.println("The first element is in the list.");
	 }
	 else
	 {
		 System.out.println("The first element is not in the list.");
	 } 
	 boolean b2 = deque.contains('I');
	 if(b2==true)
	 {
		 System.out.println("The second element is in the list.");
	 }
	 else
	 {
		 System.out.println("The second element is not in the list.");
	 }
   }
}

Test it Now

Output:

The list of the elements is given as : 
The final result of the deque is given as : [A, J, M, O]
The first element is not in the list.
The second element is not in the list.

Example 3

import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Scanner;
public class JavaDequecontainsExample3 {
   public static void main(String[] args) {
	Scanner scanner = new Scanner(System.in);
	Deque<Character> deque = new ArrayDeque<>();
     System.out.println("The list of vowels is given as : ");
     deque.add('a'); 
     deque.add('e'); 
     deque.add('i'); 
     deque.add('o'); 
     deque.add('u'); 
     System.out.println(deque);
   Object b = null;
boolean val = deque.contains(b);
   if (val == true) {
	   System.out.println("The alphabet is a vowel.");
   }
   else {
	   System.out.println("The alphabet is not a vowel.");
   }
   
   
   }
}

Test it Now

Output:

The list of vowels is given as : 
[a, e, i, o, u]
The alphabet is not a vowel.

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Java Deque contains() Method

Specified by:

Syntax:

Parameter:

Return:

Throw:

Example 1

Example 2

Example 3