Commons Collections 简明教程
Apache Commons Collections - Intersection
Apache Commons Collections 库的 CollectionUtils 类提供各种实用方法，用于涵盖广泛使用场景的常见操作。它有助于避免编写样板代码。在 jdk 8 之前，该库非常有用，因为 Java 8 的 Stream API 中现在提供了类似的功能。
CollectionUtils class of Apache Commons Collections library provides various utility methods for common operations covering wide range of use cases. It helps avoid writing boilerplate code. This library is very useful prior to jdk 8 as similar functionalities are now provided in Java 8’s Stream API.
Checking intersection
CollectionUtils 的 intersection() 方法可用于获取两个集合之间的公共对象（交集）。
intersection() method of CollectionUtils can be used to get the common objects between two collections(intersection).
Declaration
以下是 org.apache.commons.collections4.CollectionUtils.intersection() 方法的声明 -
Following is the declaration for org.apache.commons.collections4.CollectionUtils.intersection() method −
public static <O> Collection<O> intersection(Iterable<? extends O> a, Iterable<? extends O> b)Parameters
-
a − The first (sub) collection, must not be null.
-
b − The second (super) collection, must not be null.
Example
以下示例展示了 org.apache.commons.collections4.CollectionUtils.intersection() 方法的用法。我们将获取两个列表的交集。
The following example shows the usage of org.apache.commons.collections4.CollectionUtils.intersection() method. We’ll get the intersection of two lists.
import java.util.Arrays;
import java.util.List;
import org.apache.commons.collections4.CollectionUtils;
public class CollectionUtilsTester {
public static void main(String[] args) {
//checking inclusion
List<String> list1 = Arrays.asList("A","A","A","C","B","B");
List<String> list2 = Arrays.asList("A","A","B","B");
System.out.println("List 1: " + list1);
System.out.println("List 2: " + list2);
System.out.println("Commons Objects of List 1 and List 2: " + CollectionUtils.intersection(list1, list2));
}
}