Deque contains() method in Java
The contains(E e) method of Deque Interface check for the presence of the element e in the Deque container. If the Deque contains one occurrence of the element, then it returns true else it returns false.
Syntax:
boolean contains(Object o)
Parameters: This method accepts a mandatory parameter o which is the element that needs to be tested if it is present in the Deque or not.
Return Value: The method returns True if the element is present in the Deque otherwise it returns False.
Exceptions: The function throws two exceptions as shown below:
-
ClassCastException – if the type of the specified element is incompatible with this deque. It is optional.
- NullPointerException – if the specified element is null and this Deque does not permit null elements (optional). It is optional.
Below programs illustrate the contains() method in Java:
Program 1: With the help of LinkedList.
import java.util.*;
public class GFG {
public static void main(String args[])
{
Deque<String> de_que = new LinkedList<String>();
de_que.add( "Welcome" );
de_que.add( "To" );
de_que.add( "Geeks" );
de_que.add( "4" );
de_que.add( "Geeks" );
System.out.println( "Deque: " + de_que);
System.out.println( "Does the deque contains 'Geeks'? "
+ de_que.contains( "Geeks" ));
System.out.println( "Does the deque contains '4'? "
+ de_que.contains( "4" ));
System.out.println( "Does the deque contains 'No'? "
+ de_que.contains( "No" ));
}
}
|
Output:
Deque: [Welcome, To, Geeks, 4, Geeks]
Does the deque contains 'Geeks'? true
Does the deque contains '4'? true
Does the deque contains 'No'? false
Program 2:
import java.util.*;
public class GFG {
public static void main(String args[])
{
Deque<Integer> de_que = new LinkedList<Integer>();
de_que.add( 10 );
de_que.add( 15 );
de_que.add( 30 );
de_que.add( 20 );
de_que.add( 5 );
System.out.println( "Deque: " + de_que);
System.out.println( "Does the Deque contains '15'? "
+ de_que.contains( 15 ));
System.out.println( "Does the Deque contains '2'? "
+ de_que.contains( 2 ));
System.out.println( "Does the Deque contains '10'? "
+ de_que.contains( 10 ));
}
}
|
Output:
Deque: [10, 15, 30, 20, 5]
Does the Deque contains '15'? true
Does the Deque contains '2'? false
Does the Deque contains '10'? true
Program 3: With the help of ArrayDeque.
import java.util.*;
public class GFG {
public static void main(String args[])
{
Deque<Integer> de_que = new ArrayDeque<Integer>();
de_que.add( 10 );
de_que.add( 15 );
de_que.add( 30 );
de_que.add( 20 );
de_que.add( 5 );
System.out.println( "Deque: " + de_que);
System.out.println( "Does the Deque contains '15'? "
+ de_que.contains( 15 ));
System.out.println( "Does the Deque contains '2'? "
+ de_que.contains( 2 ));
System.out.println( "Does the Deque contains '10'? "
+ de_que.contains( 10 ));
}
}
|
Output:
Deque: [10, 15, 30, 20, 5]
Does the Deque contains '15'? true
Does the Deque contains '2'? false
Does the Deque contains '10'? true
Program 4: With the help of ConcurrentLinkedDeque.
import java.util.*;
import java.util.concurrent.ConcurrentLinkedDeque;
public class GFG {
public static void main(String args[])
{
Deque<Integer> de_que = new ConcurrentLinkedDeque<Integer>();
de_que.add( 10 );
de_que.add( 15 );
de_que.add( 30 );
de_que.add( 20 );
de_que.add( 5 );
System.out.println( "Deque: " + de_que);
System.out.println( "Does the Deque contains '15'? "
+ de_que.contains( 15 ));
System.out.println( "Does the Deque contains '2'? "
+ de_que.contains( 2 ));
System.out.println( "Does the Deque contains '10'? "
+ de_que.contains( 10 ));
}
}
|
Output:
Deque: [10, 15, 30, 20, 5]
Does the Deque contains '15'? true
Does the Deque contains '2'? false
Does the Deque contains '10'? true
Program 5: With the help of LinkedBlockingDeque.
import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;
public class GFG {
public static void main(String args[])
{
Deque<Integer> de_que = new LinkedBlockingDeque<Integer>();
de_que.add( 10 );
de_que.add( 15 );
de_que.add( 30 );
de_que.add( 20 );
de_que.add( 5 );
System.out.println( "Deque: " + de_que);
System.out.println( "Does the Deque contains '15'? "
+ de_que.contains( 15 ));
System.out.println( "Does the Deque contains '2'? "
+ de_que.contains( 2 ));
System.out.println( "Does the Deque contains '10'? "
+ de_que.contains( 10 ));
}
}
|
Output:
Deque: [10, 15, 30, 20, 5]
Does the Deque contains '15'? true
Does the Deque contains '2'? false
Does the Deque contains '10'? true
Note: The exceptions are compiler dependent, hence cannot be shown in the program.
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/Deque.html#contains-java.lang.Object-
Last Updated :
21 Sep, 2018
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