Java BlockingDeque removeFirstOccurrence()方法及示例

BlockingDeque 的 removeFirstOccurrence() 方法会从这个deque中删除第一次出现的指定元素。如果该deque不包含该元素，它将保持不变。如果这个deque包含指定的元素，则返回true，否则返回false。

语法

public boolean removeFirstOccurrence(Object o)

参数： 该方法接受一个强制性参数 o ，它指定了要从Deque容器中删除的元素。

返回： 如果该元素存在并从Deque容器中删除，该方法返回 true ，否则返回 false

注意 ： BlockingDeque 的 removeFirstOccurrence() 方法继承自Java中的LinkedBlockingDeque类。

以下程序说明了BlockingDeque的removeFirstOccurrence()方法。

程序1： 当元素存在时

// Java Program to demonstrate removeFirstOccurrence()// 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 InterruptedException    {         // create object of BlockingDeque        BlockingDeque<Integer> BD            = new LinkedBlockingDeque<Integer>();         // Add numbers to end of BlockingDeque        BD.add(15);        BD.add(20);        BD.add(20);        BD.add(15);         // print Deque        System.out.println("Blocking Deque: " + BD);         if (BD.removeFirstOccurrence(15))            System.out.println("First occurrence of 15 removed");        else            System.out.println("15 not present and not removed");         // prints the Deque after removal        System.out.println("Blocking Deque: " + BD);    }}

输出

Blocking Deque: [15, 20, 20, 15]First occurrence of 15 removedBlocking Deque: [20, 20, 15]

程序2： 当元素不存在时

// Java Program to demonstrate removeFirstOccurrence()// 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 InterruptedException    {         // create object of BlockingDeque        BlockingDeque<Integer> BD            = new LinkedBlockingDeque<Integer>();         // Add numbers to end of BlockingDeque        BD.add(15);        BD.add(20);        BD.add(20);        BD.add(15);         // print Deque        System.out.println("Blocking Deque: " + BD);         if (BD.removeFirstOccurrence(10))            System.out.println("First occurrence of 10 removed");        else            System.out.println("10 not present and not removed");         // prints the Deque after removal        System.out.println("Blocking Deque: " + BD);    }}

输出

Blocking Deque: [15, 20, 20, 15]10 not present and not removedBlocking Deque: [15, 20, 20, 15]

参考资料： https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingDeque.html#removeFirstOccurrence(java.lang.Object)