Java ArrayList removeAll()用法及代码示例

java.util.ArrayList类的removeAll()方法用于从此列表中删除所有包含在指定集合中的元素。

用法:

public boolean removeAll(Collection c)

参数：此方法将集合c作为包含要从此列表中删除的元素的参数。

返回值：如果此列表由于调用而更改，则此方法返回true。

异常：如果此列表包含null元素并且指定的集合不允许null元素(可选)，或者指定的collection为null，则此方法引发NullPointerException。

以下示例说明了removeAll()方法。

示例1:

// Java program to demonstrate 
// removeAll() method for Integer value 
  
import java.util.*; 
  
public class GFG1 { 
    public static void main(String[] argv) throws Exception 
    { 
  
        try { 
  
            // Creating object of ArrayList<Integer> 
            ArrayList<Integer> 
                arrlist1 = new ArrayList<Integer>(); 
  
            // Populating arrlist1 
            arrlist1.add(1); 
            arrlist1.add(2); 
            arrlist1.add(3); 
            arrlist1.add(4); 
            arrlist1.add(5); 
  
            // print arrlist1 
            System.out.println("ArrayList before "
                               + "removeAll() operation : "
                               + arrlist1); 
  
            // Creating another object of  ArrayList<Integer> 
            ArrayList<Integer> 
                arrlist2 = new ArrayList<Integer>(); 
            arrlist2.add(1); 
            arrlist2.add(2); 
            arrlist2.add(3); 
  
            // print arrlist2 
            System.out.println("Collection Elements"
                               + " to be removed : "
                               + arrlist2); 
  
            // Removing elements from arrlist 
            // specified in arrlist2 
            // using removeAll() method 
            arrlist1.removeAll(arrlist2); 
  
            // print arrlist1 
            System.out.println("ArrayList after "
                               + "removeAll() operation : "
                               + arrlist1); 
        } 
  
        catch (NullPointerException e) { 
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

输出：

ArrayList before removeAll() operation : [1, 2, 3, 4, 5]
Collection Elements to be removed : [1, 2, 3]
ArrayList after removeAll() operation : [4, 5]

示例2:对于NullPointerException

// Java program to demonstrate 
// removeAll() method for Integer value 
  
import java.util.*; 
  
public class GFG1 { 
    public static void main(String[] argv) throws Exception 
    { 
  
        try { 
  
            // Creating object of ArrayList<Integer> 
            ArrayList<Integer> 
                arrlist1 = new ArrayList<Integer>(); 
  
            // Populating arrlist1 
            arrlist1.add(1); 
            arrlist1.add(2); 
            arrlist1.add(3); 
            arrlist1.add(4); 
            arrlist1.add(5); 
  
            // print arrlist1 
            System.out.println("ArrayList before "
                               + "removeAll() operation : "
                               + arrlist1); 
  
            // Creating another object of  ArrayList<Integer> 
            ArrayList<Integer> 
                arrlist2 = null; 
  
            // print arrlist2 
            System.out.println("Collection Elements"
                               + " to be removed : "
                               + arrlist2); 
  
            System.out.println("\nTrying to pass "
                               + "null as a specified elelemnt\n"); 
  
            // Removing elements from arrlist 
            // specified in arrlist2 
            // using removeAll() method 
            arrlist1.removeAll(arrlist2); 
  
            // print arrlist1 
            System.out.println("ArrayList after "
                               + "removeAll() operation : "
                               + arrlist1); 
        } 
  
        catch (NullPointerException e) { 
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

输出：

ArrayList before removeAll() operation : [1, 2, 3, 4, 5]
Collection Elements to be removed : null

Trying to pass null as a specified elelemnt

Exception thrown : java.lang.NullPointerException

相关用法

注：本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 ArrayList removeAll() 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。