java - 如何在 Collection 中找到相同的对？

Question

如果我有集合集合。而且我必须在 Collection 中找到相同的对，即：

收藏：

• 设置 {Object_A，Object_B，Object_C}
• 设置 {Object_A、Object_B、Object_F}

如何在 Collection> 中找到对：Object_A-Object_B？可以为此目的使用什么 Java 库？

Answer 1

如果你想使用一个库，你可以使用Google Guava，然后简单地调用：

Sets.intersection(setOne, setTwo);

见。Sets.intersection()

例如：

Sets.SetView<String> intersectionView = Sets.intersection(
    ImmutableSet.of("Object_A", "Object_B", "Object_C"),
    ImmutableSet.of("Object_A", "Object_B", "Object_D"));
Set<String> intersectionSet = intersectionView.immutableCopy();

intersectionView将只是一个视图"Object_A"并"Object_B"作为元素，由两个原始集支持。intersectionSet将是一组不可变的交集。

根据您的需要（可变性等），请参阅 Guava 文档以获取更多详细信息和替代方案。

Answer 2

以下示例将有所帮助。

import java.util.Collection;
import java.util.HashSet;
import java.util.Arrays;

class Identical {
      public static void main( String  [] args ) {

          Collection<String> listOne = Arrays.asList("Object_A","Object_B",
                                                    "Object_C");

          Collection<String> listTwo = Arrays.asList("Object_A","Object_B",
                                                    "Object_F");

          Collection<String> similar = new HashSet<String>( listOne );
          Collection<String> different = new HashSet<String>();
          different.addAll( listOne );
          different.addAll( listTwo );

          similar.retainAll( listTwo );
          different.removeAll( similar );

      }
}

Answer 3

Set<String> setA = new HashSet<>(Arrays.asList("one", "two", "three"));
Set<String> setB = new HashSet<>(Arrays.asList("one", "two", "four"));

Set<String> intersection = new HashSet<>(setA);
intersection.retainAll(setB);
System.out.println("intersection: " + intersection);