El método contains(E e) de la interfaz Deque verifica la presencia del elemento e en el contenedor Deque. Si el Deque contiene una aparición del elemento, devuelve verdadero; de lo contrario, devuelve falso.
Sintaxis:
boolean contains(Object o)
Parámetros: Este método acepta un parámetro obligatorio o cual es el elemento que se necesita probar si está presente en el Deque o no.
Valor devuelto: el método devuelve True si el elemento está presente en Deque; de lo contrario, devuelve False.
Excepciones: la función lanza dos excepciones como se muestra a continuación:
- ClassCastException : si el tipo del elemento especificado es incompatible con esta deque. es opcional
- NullPointerException : si el elemento especificado es nulo y este Deque no permite elementos nulos (opcional). es opcional
Los siguientes programas ilustran el método contains() en Java:
Programa 1: Con la ayuda de LinkedList .
// Java code to illustrate contains()
// method of Deque in Java
import java.util.*;
public class GFG {
public static void main(String args[])
{
// Creating an empty Deque
Deque<String> de_que = new LinkedList<String>();
// Use add() method to add elements into the Queue
de_que.add("Welcome");
de_que.add("To");
de_que.add("Geeks");
de_que.add("4");
de_que.add("Geeks");
// Displaying the Deque
System.out.println("Deque: " + de_que);
// Check for "Geeks" in the deque
System.out.println("Does the deque contains 'Geeks'? "
+ de_que.contains("Geeks"));
// Check for "4" in the deque
System.out.println("Does the deque contains '4'? "
+ de_que.contains("4"));
// Check if the deque contains "No"
System.out.println("Does the deque contains 'No'? "
+ de_que.contains("No"));
}
}
Producción:
Deque: [Welcome, To, Geeks, 4, Geeks] Does the deque contains 'Geeks'? true Does the deque contains '4'? true Does the deque contains 'No'? false
Programa 2:
// Java code to illustrate contains()
// method of Deque in Java
import java.util.*;
public class GFG {
public static void main(String args[])
{
// Creating an empty Deque
Deque<Integer> de_que = new LinkedList<Integer>();
// Use add() method to add elements into the Queue
de_que.add(10);
de_que.add(15);
de_que.add(30);
de_que.add(20);
de_que.add(5);
// Displaying the Deque
System.out.println("Deque: " + de_que);
// Check for '15' in the Deque
System.out.println("Does the Deque contains '15'? "
+ de_que.contains(15));
// Check for '2' in the Deque
System.out.println("Does the Deque contains '2'? "
+ de_que.contains(2));
// Check if the Deque contains '10'
System.out.println("Does the Deque contains '10'? "
+ de_que.contains(10));
}
}
Producción:
Deque: [10, 15, 30, 20, 5] Does the Deque contains '15'? true Does the Deque contains '2'? false Does the Deque contains '10'? true
Programa 3: Con la ayuda de ArrayDeque .
// Java code to illustrate contains()
// method of Deque in Java
import java.util.*;
public class GFG {
public static void main(String args[])
{
// Creating an empty Deque
Deque<Integer> de_que = new ArrayDeque<Integer>();
// Use add() method to add elements into the Queue
de_que.add(10);
de_que.add(15);
de_que.add(30);
de_que.add(20);
de_que.add(5);
// Displaying the Deque
System.out.println("Deque: " + de_que);
// Check for '15' in the Deque
System.out.println("Does the Deque contains '15'? "
+ de_que.contains(15));
// Check for '2' in the Deque
System.out.println("Does the Deque contains '2'? "
+ de_que.contains(2));
// Check if the Deque contains '10'
System.out.println("Does the Deque contains '10'? "
+ de_que.contains(10));
}
}
Producción:
Deque: [10, 15, 30, 20, 5] Does the Deque contains '15'? true Does the Deque contains '2'? false Does the Deque contains '10'? true
Programa 4: Con la ayuda de ConcurrentLinkedDeque .
// Java code to illustrate contains()
// method of Deque in Java
import java.util.*;
import java.util.concurrent.ConcurrentLinkedDeque;
public class GFG {
public static void main(String args[])
{
// Creating an empty Deque
Deque<Integer> de_que = new ConcurrentLinkedDeque<Integer>();
// Use add() method to add elements into the Queue
de_que.add(10);
de_que.add(15);
de_que.add(30);
de_que.add(20);
de_que.add(5);
// Displaying the Deque
System.out.println("Deque: " + de_que);
// Check for '15' in the Deque
System.out.println("Does the Deque contains '15'? "
+ de_que.contains(15));
// Check for '2' in the Deque
System.out.println("Does the Deque contains '2'? "
+ de_que.contains(2));
// Check if the Deque contains '10'
System.out.println("Does the Deque contains '10'? "
+ de_que.contains(10));
}
}
Producción:
Deque: [10, 15, 30, 20, 5] Does the Deque contains '15'? true Does the Deque contains '2'? false Does the Deque contains '10'? true
Programa 5: Con la ayuda de LinkedBlockingDeque .
// Java code to illustrate contains()
// method of Deque in Java
import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;
public class GFG {
public static void main(String args[])
{
// Creating an empty Deque
Deque<Integer> de_que = new LinkedBlockingDeque<Integer>();
// Use add() method to add elements into the Queue
de_que.add(10);
de_que.add(15);
de_que.add(30);
de_que.add(20);
de_que.add(5);
// Displaying the Deque
System.out.println("Deque: " + de_que);
// Check for '15' in the Deque
System.out.println("Does the Deque contains '15'? "
+ de_que.contains(15));
// Check for '2' in the Deque
System.out.println("Does the Deque contains '2'? "
+ de_que.contains(2));
// Check if the Deque contains '10'
System.out.println("Does the Deque contains '10'? "
+ de_que.contains(10));
}
}
Producción:
Deque: [10, 15, 30, 20, 5] Does the Deque contains '15'? true Does the Deque contains '2'? false Does the Deque contains '10'? true
Nota: Las excepciones dependen del compilador, por lo que no se pueden mostrar en el programa.
Referencia: https://docs.oracle.com/javase/8/docs/api/java/util/Deque.html#contains-java.lang.Object-