交并LinkedList

Question

我有两个列表，它们都添加了整数。我想把这两份名单和工会联系起来。我有我的代码，但出于某种原因，它无法编译。

对于为什么我不能简单地使用LinkedList.intersection(argument, argument)，有什么建议吗？

import java.util.HashSet;
import java.util.LinkedList;
import java.util.Set;

public class IntegerSet 
{


    public static void main(String args[]) {


        LinkedList<Double> list1 = new LinkedList<Double>();
        list1.add((double) 5);
        list1.add((double) 15);
        list1.add((double) 3);
        list1.add((double) 15);


        LinkedList<Double> list2 = new LinkedList<Double>();
        list2.add((double) 15);
        list2.add((double) 8);
        list2.add((double) 16);
        list2.add((double) 11);

        // Calculating Intersection of two Set in Java
        LinkedList<Double> intersection = LinkedList.intersection(list1, list2);
        System.out.printf("Intersection of two Set %s and %s in Java is %s %n",
                list1.toString(), list2.toString(), intersection.toString());
        System.err.println("Number of elements common in two Set : "
                           + intersection.size());

        // Calculating Union of two Set in Java
        LinkedList<Double> union = LinkedList.union(list1, list2);
        System.out.printf("Union of two Set %s and %s in Java is %s %n",
                list1.toString(), list2.toString(), union.toString());
        System.out.println("total number of element in union of two Set is : "
                            + union.size());
    }

}

Answer 1

此外，尝试在intersection和union方法上使用linked list是您在复杂性方面所能做的最糟糕的事情之一。另外，

// Calculating Union of two Set in Java
LinkedList<Double> union = LinkedList.union(list1, list2);

Set与List不一样。此外，这也存在于API接口中。

col.retainAll(otherCol) // for intersection
col.addAll(otherCol) // for union

还请看这篇文章：Java中ArrayLists的交并

第三方图书馆：Apache共用CollectionUtils