removeIf java_Java CopyOnWriteArraySet removeIf()用法及代码示例

CopyonWriteArraySet方法的removeIf()方法从此CopyOnWriteArraySet中移除满足指定条件的元素。

用法:

public boolean removeIf (Predicate filter)

参数：此方法接受强制性参数过滤器，该过滤器是基于从该集合中删除哪些元素的谓词值。

返回值：如果CopyOnWriteArraySet更改，则此方法返回布尔值，例如true。否则，此方法返回false。

异常：如果指定的谓词过滤器为null，则此方法将引发NullPointerException。

以下示例程序旨在说明CopyOnWriteArrayList类的removeIf()函数：

示例1:

// Java Program to illustrate the CopyOnWriteArraySet

// removeIf() method in Java

import java.util.concurrent.CopyOnWriteArraySet;

import java.util.*;

public class GFG {

public static void main(String[] args)

{

// create object of CopyOnWriteArraySet

CopyOnWriteArraySet ArrSet

= new CopyOnWriteArraySet();

// Add elements

ArrSet.add(10);

ArrSet.add(20);

ArrSet.add(30);

ArrSet.add(40);

ArrSet.add(50);

ArrSet.add(60);

ArrSet.add(70);

ArrSet.add(80);

ArrSet.add(90);

// print CopyOnWriteArraySet

System.out.println("CopyOnWriteArraySet: "

+ ArrSet);

// if a number in the set is

// divisible by 3, then remove it

ArrSet.removeIf(number -> number % 3 == 0);

// print updated CopyOnWriteArraySet

System.out.println("Updated CopyOnWriteArraySet: "

+ ArrSet);

}

}

输出：

CopyOnWriteArraySet: [10, 20, 30, 40, 50, 60, 70, 80, 90]

Updated CopyOnWriteArraySet: [10, 20, 40, 50, 70, 80]

示例2:

// Java Program to illustrate the CopyOnWriteArraySet

// removeIf() method in Java

import java.util.concurrent.CopyOnWriteArraySet;

import java.util.*;

public class GFG {

public static void main(String[] args)

{

// create object of CopyOnWriteArraySet

CopyOnWriteArraySet ArrSet

= new CopyOnWriteArraySet();

// Add elements

ArrSet.add("GeeksforGeeks");

ArrSet.add("GFG");

ArrSet.add("Geeks");

ArrSet.add("Gfg");

// print CopyOnWriteArraySet

System.out.println("CopyOnWriteArraySet: "

+ ArrSet);

try {

// if a number in the set is

// divisible by 3, then remove it

// This will throw NullPointerException

ArrSet.removeIf(null);

}

catch (Exception e) {

System.out.println(e);

}

}

}

输出：

CopyOnWriteArraySet: [GeeksforGeeks, GFG, Geeks, Gfg]

java.lang.NullPointerException