Java AbstractSet removeAll()用法及代碼示例

Java AbstractSet類的removeAll()方法用於從該集合中刪除所有包含在指定集合中的元素。

用法:

public boolean removeAll(Collection c)

參數：此方法將集合c作為包含要從該集合中刪除的元素的參數。

返回值：如果此集合因調用而更改，則此方法返回true。

異常：該方法引發三種類型的異常：

UnsupportedOperationException–如果這個集合不支持該操作，則拋出此錯誤。
ClassCastException–當此集合的元素的類與指定的集合不兼容時，拋出此錯誤。
NullPointerException –當此集合包含null元素並且指定的集合不允許null元素時，或者如果collection為null，則拋出此錯誤。

以下示例說明了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[] args) throws Exception 
    { 
  
        try { 
  
            // Creating object of AbstractSet<Integer> 
            AbstractSet<Integer> 
                abs_set = new TreeSet<Integer>(); 
  
            // Populating abs_set 
            abs_set.add(1); 
            abs_set.add(2); 
            abs_set.add(3); 
            abs_set.add(4); 
            abs_set.add(5); 
  
            // print abs_set 
            System.out.println("AbstractSet before "
                               + "removeAll() operation : "
                               + abs_set); 
  
            // Creating another object of ArrayList<Integer> 
            Collection<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 AbstractSet 
            // specified in arrlist2 
            // using removeAll() method 
            abs_set.removeAll(arrlist2); 
  
            // print arrlist1 
            System.out.println("AbstractSet after "
                               + "removeAll() operation : "
                               + abs_set); 
        } 
  
        catch (NullPointerException e) { 
            System.out.println("Exception thrown : " + e); 
        } 
    } 
}

輸出：

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

示例2:對於NullPointerException

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

輸出：

AbstractSet before removeAll() operation : [1, 2, 3, 4, 5]
Collection Elements to be removed : null
Exception thrown : java.lang.NullPointerException

相關用法

注：本文由純淨天空篩選整理自Chinmoy Lenka大神的英文原創作品 AbstractSet removeAll() Method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。