Java 中 LinkedBlockingQueue size()方法
原文:https://www . geeksforgeeks . org/linkedblockingqueue-size-method-in-Java/
LinkedBlockingQueue 的 size() 方法返回 LinkedBlockingQueue 包含的元素个数。当队列为空队列时，size()返回 0，当队列已满时，size()返回队列的容量。
语法:
public int size()
返回值:该方法返回链接锁定队列中该时刻的元素数量。返回类型是 int。
下面的程序说明了 LinkedBlockingQueue 类的 size()方法:
程序 1: 在 LinkedBlockingQueue 上执行添加和删除操作，每次操作后使用 size()
// Java Program Demonstrate size()
// method of LinkedBlockingQueue
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public static void main(String[] args)
throws InterruptedException
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 4;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<String> linkedQueue
= new LinkedBlockingQueue<String>(capacityOfQueue);
// Add element using put() method
linkedQueue.put("Karan");
linkedQueue.put("Suraj");
// get size of queue using size() method
int size = linkedQueue.size();
// print elements of queue and size of queue
System.out.println("Items in Queue are " + linkedQueue);
System.out.println("Size of Queue is " + size);
// add more elements
linkedQueue.put("Harsh");
linkedQueue.put("Rahul");
// get size of queue using size() method
size = linkedQueue.size();
// print elements of queue and size of queue
System.out.println("Items in Queue are " + linkedQueue);
System.out.println("Size of Queue is " + size);
// try to remove element fom Queue
boolean try1 = linkedQueue.remove("Karan");
System.out.println("String name Karan is removed :"
+ try1);
// get size of queue using size() method
size = linkedQueue.size();
// print elements of queue and size of queue
System.out.println("Items in Queue are " + linkedQueue);
System.out.println("Size of Queue is " + size);
}
}
打印队列大小输出:
Items in Queue are [Karan, Suraj]
Size of Queue is 2
Items in Queue are [Karan, Suraj, Harsh, Rahul]
Size of Queue is 4
String name Karan is removed :true
Items in Queue are [Suraj, Harsh, Rahul]
Size of Queue is 3
程序 2: 对包含 Employee 对象的 LinkedBlockingQueue 执行添加和删除操作，每次操作后使用 size()
// Java Program Demonstrate size()
// method of LinkedBlockingQueue
import java.util.Iterator;
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
public void sizeDemo() throws InterruptedException
{
// define capacity of LinkedBlockingQueue
int capacityOfQueue = 5;
// create object of LinkedBlockingQueue
LinkedBlockingQueue<Employee> linkedQueue
= new LinkedBlockingQueue<Employee>(capacityOfQueue);
// get size of queue using size() method
int size = linkedQueue.size();
System.out.println("Size of Queue " + size);
// Add element to LinkedBlockingQueue
Employee emp1 = new Employee("Ranjeet", "Tester", "29000", 27);
Employee emp2 = new Employee("Sanjeet", "Manager", "98000", 34);
Employee emp3 = new Employee("Karan", "Analyst", "44000", 30);
// Add Employee Objects to linkedQueue
// Using put(E e)
linkedQueue.put(emp1);
linkedQueue.put(emp2);
linkedQueue.put(emp3);
// print details of linkedQueue
System.out.println("\nAfter Adding some Elements queue has");
Iterator itr = linkedQueue.iterator();
while (itr.hasNext())
System.out.println(itr.next());
// get size of queue using size() method
size = linkedQueue.size();
System.out.println("\nAfter Adding Size of Queue " + size);
// remove employee2 name Sanjeet and Ranjeet from linkedQueue
linkedQueue.remove(emp2);
linkedQueue.remove(emp1);
// print details of linkedQueue
System.out.println("\nAfter removing Some Elements");
itr = linkedQueue.iterator();
while (itr.hasNext())
System.out.println(itr.next());
// get size of queue using size() method
size = linkedQueue.size();
System.out.println("\nAfter removing size of Queue " + size);
}
// create an Employee Object with name,
// position, salary and age as attributes
public class Employee {
public String name;
public String position;
public String salary;
public int Age;
Employee(String name, String position,
String salary, int age)
{
this.name = name;
this.position = position;
this.salary = salary;
this.Age = age;
}
@Override
public String toString()
{
return "Employee [name=" + name + ", position="
+ position + ", salary=" + salary + ", Age=" + Age + "]";
}
}
// Main Method
public static void main(String[] args)
{
GFG gfg = new GFG();
try {
gfg.sizeDemo();
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
输出:
Size of Queue 0
After Adding some Elements queue has
Employee [name=Ranjeet, position=Tester, salary=29000, Age=27]
Employee [name=Sanjeet, position=Manager, salary=98000, Age=34]
Employee [name=Karan, position=Analyst, salary=44000, Age=30]
After Adding Size of Queue 3
After removing Some Elements
Employee [name=Karan, position=Analyst, salary=44000, Age=30]
After removing size of Queue 1
打印队列的大小
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