Java BlockingDeque addFirst()用法及代码示例

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

用法:

public void addFirst(E e)

参数：此方法接受强制参数e，该参数是要插入到BlockingDeque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

注意：BlockingDeque的addFirst()方法已从Java中的LinkedBlockingDeque类继承。

下面的程序说明BlockingQueue的addFirst()方法：

示例1:

// Java Program Demonstrate addFirst() 
// method of BlockingDeque 
  
import java.util.concurrent.LinkedBlockingDeque; 
import java.util.concurrent.BlockingDeque; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
        throws IllegalStateException 
    { 
  
        // create object of BlockingDeque 
        BlockingDeque<Integer> BD 
            = new LinkedBlockingDeque<Integer>(); 
  
        // Add numbers to front of BlockingDeque 
        BD.addFirst(7855642); 
        BD.addFirst(35658786); 
        BD.addFirst(5278367); 
        BD.addFirst(74381793); 
  
        // before removing print Dequq 
        System.out.println("Blocking Deque: " + BD); 
    } 
}

输出：

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

示例2:

// Java Program Demonstrate addFirst() 
// method of BlockingDeque 
// when it is Full 
import java.util.concurrent.LinkedBlockingDeque; 
import java.util.concurrent.BlockingDeque; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
        throws IllegalStateException 
    { 
  
        // create object of BlockingDeque 
        // size of list 
        BlockingDeque<Integer> BD 
            = new LinkedBlockingDeque<Integer>(3); 
  
        // Add numbers to front of BlockingDeque 
        BD.addFirst(7855642); 
        BD.addFirst(35658786); 
        BD.addFirst(5278367); 
  
        // it is full 
        BD.addFirst(74381793); 
  
        // before removing print Deque 
        System.out.println("Blocking Deque: " + BD); 
    } 
}

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:24)

示例3:

// Java Program Demonstrate addFirst() 
// method of BlockingDeque 
// when nill is inserted 
  
import java.util.concurrent.BlockingDeque; 
import java.util.concurrent.LinkedBlockingDeque; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
        throws IllegalStateException 
    { 
  
        // create object of BlockingDeque 
        BlockingDeque<Integer> BD 
            = new LinkedBlockingDeque<Integer>(); 
  
        // Add numbers to front of BlockingDeque 
        BD.addFirst(7855642); 
        BD.addFirst(35658786); 
        BD.addFirst(5278367); 
  
        // NULL 
        BD.addFirst(null); 
  
        // before removing print Deque 
        System.out.println("Blocking Deque: " + BD); 
    } 
}

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:24)

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

相关用法

注：本文由纯净天空筛选整理自gopaldave大神的英文原创作品 BlockingDeque addFirst() method in Java with Examples。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。