Java LinkedBlockingDeque addFirst()用法及代码示例

如果有空间，LinkedBlockingDeque的addFirst(E e)方法会将参数中传递的元素插入到Deque的前面。如果LinkedBlockingDeque受容量限制并且没有剩余空间可插入，则它返回IllegalStateException。

用法:

public void addFirst(E e)

参数：此方法接受强制参数e，该参数是要插入LinkedBlockingDeque前面的元素。

返回值：此方法不返回任何内容。

异常：

IllegalStateException：如果由于容量限制此时无法添加元素
NullPointerException ：如果指定的元素为null

下面的程序说明PriorityBlockingQueue的addFirst()方法：

示例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]

示例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)

示例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)

参考： https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingDeque.html#add(E)

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注：本文由纯净天空筛选整理自gopaldave大神的英文原创作品 LinkedBlockingDeque addFirst() method in Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。