El método addFirst(E e) de LinkedBlockingDeque inserta el elemento pasado en el parámetro al frente de Deque si hay espacio. Si LinkedBlockingDeque tiene una capacidad restringida y no queda espacio para la inserción, devuelve una excepción IllegalStateException .
Sintaxis:
public void addFirst(E e)
Parámetros: este método acepta un parámetro obligatorio e que es el elemento que se insertará al frente de LinkedBlockingDeque.
Devoluciones: Este método no devuelve nada.
Excepción:
- IllegalStateException : si el elemento no se puede agregar en este momento debido a restricciones de capacidad
- NullPointerException : si el elemento especificado es nulo
Los siguientes programas ilustran el método addFirst() de PriorityBlockingQueue:
Programa 1:
// Java Program Demonstrate addFirst()
// method of LinkedBlockingDeque
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
// create object of LinkedBlockingDeque
LinkedBlockingDeque<Integer> LBD
= new LinkedBlockingDeque<Integer>();
// Add numbers to front of LinkedBlockingDeque
LBD.addFirst(7855642);
LBD.addFirst(35658786);
LBD.addFirst(5278367);
LBD.addFirst(74381793);
// before removing print queue
System.out.println("Linked Blocking Deque: " + LBD);
}
}
Producción:
Linked Blocking Deque: [74381793, 5278367, 35658786, 7855642]
Programa 2:
// Java Program Demonstrate addFirst()
// method of LinkedBlockingDeque
// when it is Full
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
// create object of LinkedBlockingDeque
// size of list
LinkedBlockingDeque<Integer> LBD
= new LinkedBlockingDeque<Integer>(3);
// Add numbers to front of LinkedBlockingDeque
LBD.addFirst(7855642);
LBD.addFirst(35658786);
LBD.addFirst(5278367);
// it is full
LBD.addFirst(74381793);
// before removing print queue
System.out.println("Linked Blocking Deque: " + LBD);
}
}
Producción:
Exception in thread "main" java.lang.IllegalStateException: Deque full
at java.util.concurrent.LinkedBlockingDeque.addFirst(LinkedBlockingDeque.java:326)
at GFG.main(GFG.java:23)
Programa 3:
// Java Program Demonstrate addFirst()
// method of LinkedBlockingDeque
// when nill is inserted
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
// create object of LinkedBlockingDeque
LinkedBlockingDeque<Integer> LBD
= new LinkedBlockingDeque<Integer>();
// Add numbers to front of LinkedBlockingDeque
LBD.addFirst(7855642);
LBD.addFirst(35658786);
LBD.addFirst(5278367);
// NULL
LBD.addFirst(null);
// before removing print queue
System.out.println("Linked Blocking Deque: " + LBD);
}
}
Producción:
Exception in thread "main" java.lang.NullPointerException
at java.util.concurrent.LinkedBlockingDeque.offerFirst(LinkedBlockingDeque.java:342)
at java.util.concurrent.LinkedBlockingDeque.addFirst(LinkedBlockingDeque.java:325)
at GFG.main(GFG.java:22)
Referencia: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingDeque.html#add(E)