Java LinkedBlockingDeque removeIf()方法及示例

LinkedBlockingDeque的 removeIf() 方法会从这个LinkedBlockingDeque中删除满足指定条件的元素。

语法

public boolean removeIf (Predicate<? super E> filter)

参数： 该方法接受一个强制参数filter，它是基于哪些元素被从这个Deque中删除的谓词值。

返回： 如果LinkedBlockingDeque被改变，该方法返回一个 布尔值 ，如true。否则，此方法返回false。

异常： 如果指定的Predicate过滤器为空，该方法会抛出 NullPointerException 。

下面的程序说明了LinkedBlockingDeque类的removeIf()函数。

程序1 :

// Java Program Demonstrate removeIf()
// method of LinkedBlockingDeque
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws InterruptedException
    {
  
        // Create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to end of LinkedBlockingDeque
        LBD.add(7855642);
        LBD.add(35658786);
        LBD.add(5278367);
        LBD.add(74381793);
  
        // Print Deque
        System.out.println("Linked Blocking Deque: "
                           + LBD);
  
        // If a number in the List is
        // divisible by 3, then remove it
        LBD.removeIf(number -> number % 3 == 0);
  
        System.out.println("Linked Blocking Deque: "
                           + LBD);
    }
}

输出:

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

示例2

// Java Program Demonstrate removeIf()
// method of LinkedBlockingDeque
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws InterruptedException
    {
  
        // Create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to end of LinkedBlockingDeque
        LBD.add(7855642);
        LBD.add(35658786);
        LBD.add(5278367);
        LBD.add(74381793);
  
        // Print Dequeue
        System.out.println("Linked Blocking Deque: "
                           + LBD);
  
        try {
            // if the predicate is null,
            // then it will throw NullPointerException
            LBD.removeIf(null);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出:

Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793]
java.lang.NullPointerException

参考资料: https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/LinkedBlockingDeque.html#removeIf-java.util.function.Predicate-