如何从两个数组列表中删除公共值

list collections java arraylist

2022-09-01 18:07:32

如何从两个 ArrayList 中删除公共值？

让我们考虑我有两个数组列表，如下所示：

ArrayList1 = [1,2,3,4]
ArrayList1 = [2,3,4,6,7]

我希望结果为：

ArrayListFinal = [1,6,7]

我该怎么做？

答案 1

以下是您可以遵循的算法来完成任务：

构造两个数组的并集
构造两个数组的交集
从并集中减去交集以获得结果

Java 集合支持 addAll、removeAll 和 retainAll。用于构造并集、构造交集和减法，如下所示：addAllretainAllremoveAll

// Make the two lists
List<Integer> list1 = Arrays.asList(1, 2, 3, 4);
List<Integer> list2 = Arrays.asList(2, 3, 4, 6, 7);
// Prepare a union
List<Integer> union = new ArrayList<Integer>(list1);
union.addAll(list2);
// Prepare an intersection
List<Integer> intersection = new ArrayList<Integer>(list1);
intersection.retainAll(list2);
// Subtract the intersection from the union
union.removeAll(intersection);
// Print the result
for (Integer n : union) {
    System.out.println(n);
}

答案 2

你实际上是在要求对称差分。

List<Integer> aList = new ArrayList<>(Arrays.asList(1, 2, 3, 4));
List<Integer> bList = new ArrayList<>(Arrays.asList(2, 3, 4, 6, 7));
// Union is all from both lists.
List<Integer> union = new ArrayList(aList);
union.addAll(bList);
// Intersection is only those in both.
List<Integer> intersection = new ArrayList(aList);
intersection.retainAll(bList);
// Symmetric difference is all except those in both.    
List<Integer> symmetricDifference = new ArrayList(union);
symmetricDifference.removeAll(intersection);

System.out.println("aList: " + aList);
System.out.println("bList: " + bList);
System.out.println("union: " + union);
System.out.println("intersection: " + intersection);
System.out.println("**symmetricDifference: " + symmetricDifference+"**");

指纹：

aList: [1, 2, 3, 4]
bList: [2, 3, 4, 6, 7]
union: [1, 2, 3, 4, 2, 3, 4, 6, 7]
intersection: [2, 3, 4]
**symmetricDifference: [1, 6, 7]**