java Java 中的 LinkedBlockingDeque addFirst()方法

Java 中的 LinkedBlockingDeque addFirst()方法

原文:https://www . geeksforgeeks . org/link edblockingeque-addfirst-method-in-Java/

的 addFirst(E e) 方法 link edblockingeque将参数中传递的元素插入到 Deque 的前面(如果有空间的话)。如果链接锁定请求受到容量限制，并且没有空间可供插入，它将返回一个非法状态异常。

语法:

public void addFirst(E e)

参数:该方法接受一个强制参数 e ，它是要插入链接锁定请求前面的元素。

返回:这个方法不返回任何东西。

异常:

[T0】 illegalstatexception 【T1]: If the element cannot be added due to capacity limitation at this time.
[T0】 NullPointerException 【T1]: If the specified element is empty.

下面的程序说明了优先级阻塞队列的 addFirst()方法:

程序 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);
    }
}

输出:

Linked Blocking Deque: [74381793, 5278367, 35658786, 7855642]

节目 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);
    }
}

输出:

Exception in thread "main" java.lang.IllegalStateException: Deque full
    at java.util.concurrent.LinkedBlockingDeque.addFirst(LinkedBlockingDeque.java:326)
    at GFG.main(GFG.java:23)

节目 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);
    }
}

输出:

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)