Java Deque contains() Method with Examples

by Online Tutorials Library July 22, 2022

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 with Examples

Java Deque contains() Method

Specified by:

Syntax:

Parameter:

Return:

Throw:

Example 1

Example 2

Example 3

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