El método peek() de LinkedBlockingQueue devuelve el encabezado de LinkedBlockingQueue. Recupera el valor del encabezado de LinkedBlockingQueue pero no lo elimina. Si LinkedBlockingQueue está vacío, este método devuelve un valor nulo.
Sintaxis:
public E peek()
Valor devuelto: este método devuelve el encabezado de LinkedBlockingQueue.
Los siguientes programas ilustran el método peek() de la clase LinkedBlockingQueue:
Programa 1: Devolver el encabezado de LinkedBlockingQueue usando el método peek() donde LinkedBlockingQueue de capacidad 7 contiene una lista de nombres
// Java Program Demonstrate peek()
// method of LinkedBlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public static void main(String[] args)
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 7;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<String> linkedQueue
= new LinkedBlockingQueue<String>(capacityOfQueue);
// Add element to LinkedBlockingQueue
linkedQueue.add("John");
linkedQueue.add("Tom");
linkedQueue.add("Clark");
linkedQueue.add("Kat");
// find head of linkedQueue using peek() method
String head = linkedQueue.peek();
// print result
System.out.println("Queue is " + linkedQueue);
// print head of queue
System.out.println("Head of Queue is " + head);
// removing one element
linkedQueue.remove();
// again get head of queue
head = linkedQueue.peek();
// print result
System.out.println("\nRemoving one element from Queue\n");
System.out.println("Queue is " + linkedQueue);
// print head of queue
System.out.println("Head of Queue is " + head);
}
}
Queue is [John, Tom, Clark, Kat] Head of Queue is John Removing one element from Queue Queue is [Tom, Clark, Kat] Head of Queue is Tom
Programa 2: encontrar el encabezado de LinkedBlockingQueue que contiene una lista de empleados
// Java Program Demonstrate peek()
// method of LinkedBlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public void findPeek()
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 7;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<Employee> linkedQueue
= new LinkedBlockingQueue<Employee>(capacityOfQueue);
// Add element to LinkedBlockingQueue
Employee emp1 = new Employee("Ravi", "Tester", "39000");
Employee emp2 = new Employee("Sanjeet", "Manager", "98000");
// Add Employee Objects to linkedQueue
linkedQueue.add(emp1);
linkedQueue.add(emp2);
// print head then remove element
// and follow same process again
// until the queue becomes empty
while (linkedQueue.size() != 0) {
// find head of linkedQueue using peek() method
Employee head = linkedQueue.peek();
// print results
System.out.println("Head of list");
System.out.println("Employee Name : " + head.name);
System.out.println("Employee Position : " + head.position);
System.out.println("Employee Salary : " + head.salary);
linkedQueue.remove();
if (linkedQueue.size() != 0)
System.out.println("\nRemoving one element from Queue\n");
}
}
// create an Employee Object with
// position and salary as an attribute
public class Employee {
public String name;
public String position;
public String salary;
Employee(String name, String position, String salary)
{
this.name = name;
this.position = position;
this.salary = salary;
}
@Override
public String toString()
{
return "Employee [name=" + name + ", position="
+ position + ", salary=" + salary + "]";
}
}
// Main Method
public static void main(String[] args)
{
GFG gfg = new GFG();
gfg.findPeek();
}
}
Head of list Employee Name : Ravi Employee Position : Tester Employee Salary : 39000 Removing one element from Queue Head of list Employee Name : Sanjeet Employee Position : Manager Employee Salary : 98000
Referencia: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/LinkedBlockingQueue.html#peek–
Publicación traducida automáticamente
Artículo escrito por AmanSingh2210 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA