Java 中的抽象集合 removeAll()方法，示例
原文:https://www . geesforgeks . org/abstract collection-remove all-method-in-Java-with-example/
Java . util . abstract Collection . remove all(Collection col)方法用于从抽象集合中移除指定集合中存在的所有元素。
语法:
AbstractCollection.removeAll(Collection col)
参数:该方法接受一个强制参数列，它是要从抽象集合中移除其元素的集合。
返回值:如果抽象集合由于操作而改变，该方法返回真，否则返回假。
异常:如果指定的集合为空，该方法将抛出空指针异常。
下面的程序说明了方法:
程序 1:
// Java code to illustrate removeAll()
import java.util.*;
public class AbstractCollectionDemo {
public static void main(String args[])
{
// Creating an empty AbstractCollection
AbstractCollection<String> collection
= new ArrayList<String>();
// Use add() method to add
// elements in the AbstractCollection
collection.add("Geeks");
collection.add("for");
collection.add("Geeks");
collection.add("10");
collection.add("20");
// Output the AbstractCollection
System.out.println("AbstractCollection: "
+ collection);
// Creating an empty AbstractCollection
AbstractCollection<String> colcollection
= new ArrayList<String>();
// Use add() method to add
// elements in the AbstractCollection
colcollection.add("Geeks");
colcollection.add("for");
colcollection.add("Geeks");
// Remove the head using remove()
boolean changed
= collection.removeAll(colcollection);
// Print the result
if (changed)
System.out.println("Collection removed");
else
System.out.println("Collection not removed");
// Print the final AbstractCollection
System.out.println("Final AbstractCollection: "
+ collection);
}
}
Output:
AbstractCollection: [Geeks, for, Geeks, 10, 20]
Collection removed
Final AbstractCollection: [10, 20]
程序 2:
// Java code to illustrate removeAll()
import java.util.*;
public class AbstractCollectionDemo {
public static void main(String args[])
{
// Creating an empty AbstractCollection
AbstractCollection<Integer> collection
= new ArrayList<Integer>();
// Use add() method to
// add elements in the AbstractCollection
collection.add(1);
collection.add(2);
collection.add(3);
collection.add(10);
collection.add(20);
// Output the AbstractCollection
System.out.println("AbstractCollection: "
+ collection);
// Creating an empty AbstractCollection
AbstractCollection<Integer> colcollection
= new ArrayList<Integer>();
// Use add() method to add elements
// in the AbstractCollection
colcollection.add(30);
colcollection.add(40);
colcollection.add(50);
// Remove the head using remove()
boolean changed
= collection.removeAll(colcollection);
// Print the result
if (changed)
System.out.println("Collection removed");
else
System.out.println("Collection not removed");
// Print the final AbstractCollection
System.out.println("Final AbstractCollection: "
+ collection);
}
}
Output:
AbstractCollection: [1, 2, 3, 10, 20]
Collection not removed
Final AbstractCollection: [1, 2, 3, 10, 20]
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