Java BlockingQueue put()方法及示例

如果队列没有满， BlockingQueue 接口的 put(E e) 方法将作为参数传递给方法的元素插入到这个BlockingQueue的尾部。如果队列已满，那么该方法将等待空间可用，在空间可用后，它将把元素插入BlockingQueue。

语法

public void put(E e) throws InterruptedException

参数： 该方法需要一个强制性的参数 e ，它是要插入LinkedBlockingQueue中的元素。

返回值： 该方法不返回任何东西。

异常： 该方法抛出以下异常。

• InterruptedException – 当等待队列可用时发生中断。
• NullPointerException – 如果传递给方法的元素是空的。

注意 ： BlockingQueue 的 put() 方法继承自Java中的 Queue 类。

以下程序说明了BlockingQueue类的put(E e)方法：

程序1 :

// Java Program Demonstrate put(E e)
// 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 using put() method
        BQ.put("Karan");
        BQ.put("Suraj");
        BQ.put("Harsh");
        BQ.put("Rahul");
 
        // print elements of queue
        System.out.println("Items in Queue are " + BQ);
    }
}

输出

Items in Queue are [Karan, Suraj, Harsh, Rahul]

程序2

// Java Program Demonstrate put()
// method of BlockingQueue
 
import java.util.Iterator;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.BlockingQueue;
public class GFG {
 
    public void PutDemo() 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("Ranjeet", "Tester", "29000", 27);
        Employee emp2 = new Employee("Sanjeet", "Manager", "98000", 34);
        Employee emp3 = new Employee("Karan", "Analyst", "44000", 30);
 
        // Add Employee Objects to BQ
        // Using put(E e)
        BQ.put(emp1);
        BQ.put(emp2);
        BQ.put(emp3);
 
        System.out.println("Details of Employees:");
        // print details of BQ
        Iterator itr = BQ.iterator();
        while (itr.hasNext())
            System.out.println(itr.next());
    }
 
    // 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.PutDemo();
        }
        catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

输出

Details of Employees:
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]

程序3

// Java Program Demonstrate put(E e)
// 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);
 
        // try to put null value in put method
        try {
            BQ.put(null);
        }
        catch (Exception e) {
            // print error details
            System.out.println("Exception: " + e);
        }
    }
}

输出

Exception: java.lang.NullPointerException

**参考资料: ** https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingQueue.html#put(E)