Java中的 SortedSet removeAll() 方法及示例

SortedSet接口的removeAll()方法用于从这个 SortedSet 中删除指定集合中包含的所有元素。
句法：

public boolean removeAll(Collection c)

参数：此方法将集合 c作为参数，其中包含要从此 SortedSet 中删除的元素。
返回值：如果此集合因调用而更改，则此方法返回true 。
异常：如果此集合包含空元素并且指定的集合不允许空元素（可选），或者指定的集合为空，则此方法抛出NullPointerException 。
注意：SortedSet 中的 removeAll() 方法继承自Java中的 Set 接口。
下面是说明removeAll()方法的示例。
示例 1：

Java

// 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 SortedSet
            SortedSet set1
                = new TreeSet();
 
            // Populating set1
            set1.add(1);
            set1.add(2);
            set1.add(3);
            set1.add(4);
            set1.add(5);
 
            // print set1
            System.out.println(
                "Set before "
                + "removeAll() operation : "
                + set1);
 
            // Creating another object of Set
            SortedSet set2
                = new TreeSet();
            set2.add(1);
            set2.add(2);
            set2.add(3);
 
            // print set2
            System.out.println(
                "Collection Elements "
                + "to be removed : "
                + set2);
 
            // Removing elements from set
            // specified in set2
            // using removeAll() method
            set1.removeAll(set2);
 
            // print set1
            System.out.println(
                "Set after "
                + "removeAll() operation : "
                + set1);
        }
 
        catch (NullPointerException e) {
            System.out.println("Exception thrown : "
                               + e);
        }
    }
}

输出：

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

示例 2：对于NullPointerException 。

Java

// 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 SortedSet
            SortedSet set1
                = new TreeSet();
 
            // Populating set1
            set1.add(1);
            set1.add(2);
            set1.add(3);
            set1.add(4);
            set1.add(5);
 
            // print set1
            System.out.println(
                "Set before "
                + "removeAll() operation : "
                + set1);
 
            // Creating another object of SortedSet
            SortedSet set2 = null;
 
            // print set2
            System.out.println(
                "Collection Elements"
                + " to be removed : "
                + set2);
 
            System.out.println(
                "\nTrying to pass "
                + "null as a specified element\n");
 
            // Removing elements from set
            // specified in set2
            // using removeAll() method
            set1.removeAll(set2);
 
            // print set1
            System.out.println(
                "Set after "
                + "removeAll() operation : "
                + set1);
        }
 
        catch (NullPointerException e) {
            System.out.println(e);
        }
    }
}

输出：

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

Trying to pass null as a specified element

java.lang.NullPointerException

参考：https: Java Java.util.Collection)