极客教程Java BlockingQueue take()方法及示例
BlockingQueue 接口的 take() 方法用于检索和删除该队列的头部。如果队列是空的，那么它将等待，直到有元素可用。如果在线程上工作并在这个过程中使用BlockingQueue，这个方法会更有效率。因此，如果没有可用的元素，最初调用take()的线程就会进入睡眠状态，让其他线程做他们需要做的事。
语法
public E take() throws InterruptedException
返回值： 该方法返回该BlockingQueue头部的值。如果队列是空的，那么它将等待，直到一个元素变得可用。
异常： 这个方法抛出以下异常。
- InterruptedException – 如果队列是空的，在等待一个元素变得可用时发生中断。
注意 ： BlockingQueue 的 take() 方法继承自Java中的 Queue 类。
以下程序说明了BlockingQueue接口的take()方法：
程序1 :
// Java Program Demonstrate take()
// method of BlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.BlockingQueue;
public class GFG {
public static void main(String[] args)
throws InterruptedException
{
// define capacity of BlockingQueue
int capacityOfQueue = 4;
// create object of BlockingQueue
BlockingQueue<String> BQ
= new LinkedBlockingQueue<String>(capacityOfQueue);
// Add element to BlockingQueue
BQ.add("Ravi");
BQ.add("Suraj");
BQ.add("Harsh");
BQ.add("Sayan");
// print elements of queue
System.out.println("Items in Queue are " + BQ);
// remove two elements from queue from head
// Applying take() method on queue to remove element
String removedItem1 = BQ.take();
// print removedItem and queue
System.out.println("Removed Item from head is "
+ removedItem1);
// print elements of queue after removing first item
System.out.println("Remaining Items in Queue are "
+ BQ);
// Applying take() method on queue to remove another element
String removedItem2 = BQ.take();
// print removedItem and queue
System.out.println("Removed Item from head is "
+ removedItem2);
// print elements of queue after removing first item
System.out.println("Remaining Items in Queue are "
+ BQ);
}
}
输出
Items in Queue are [Ravi, Suraj, Harsh, Sayan]
Removed Item from head is Ravi
Remaining Items in Queue are [Suraj, Harsh, Sayan]
Removed Item from head is Suraj
Remaining Items in Queue are [Harsh, Sayan]
程序2
// Java Program Demonstrate take()
// method of BlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.BlockingQueue;
public class GFG {
public void takeDemo() throws InterruptedException
{
// define capacity of BlockingQueue
int capacityOfQueue = 5;
// create object of BlockingQueue
BlockingQueue<Employee> BQ
= new LinkedBlockingQueue<Employee>(capacityOfQueue);
// Add element to BlockingQueue
Employee emp1 = new Employee("Ravi", "Tester", "39000");
Employee emp2 = new Employee("Sanjeet", "Manager", "98000");
// Add Employee Objects to BQ
BQ.add(emp1);
BQ.add(emp2);
// remove elements from the queue
// and follow this process again and again
// until the queue becomes empty
while (BQ.size() != 0) {
// Remove Employee item from BlockingQueue
// using take()
Employee removedEmp = BQ.take();
// print removedItem
System.out.println("Removed Item is :");
System.out.println("Employee Name - "
+ removedEmp.name);
System.out.println("Employee Position - "
+ removedEmp.position);
System.out.println("Employee Salary - "
+ removedEmp.salary);
// find size of BQ
int size = BQ.size();
// print remaining capacity value
System.out.println("\nSize of list :" + size + "\n");
}
}
// create an Employee Object with name,
// 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();
try {
gfg.takeDemo();
}
catch (Exception e) {
e.printStackTrace();
}
}
}
输出
Removed Item is :
Employee Name - Ravi
Employee Position - Tester
Employee Salary - 39000
Size of list :1
Removed Item is :
Employee Name - Sanjeet
Employee Position - Manager
Employee Salary - 98000
Size of list :0