java List 求两个数组的交集、求两个数组的差集

package com.e1Soft.jygl.util;

import java.util.HashMap;

import java.util.HashSet;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Set;

public class ArrayUtil {

public static void main(String[] args) {

//测试union

String[] arr1 = {"abc", "df", "abc"};

String[] arr2 = {"abc", "cc", "df", "d", "abc"};

String[] result_union = union(arr1, arr2);

System.out.println("求并集的结果如下：");

for (String str : result_union) {

System.out.println(str);

}

System.out.println("---------------------可爱的分割线------------------------");

//测试insect

List result_insect = intersect(arr1, arr2);

System.out.println("求交集的结果如下：");

for (Object str : result_insect) {

System.out.println(str);

}

System.out.println("---------------------疯狂的分割线------------------------");

//测试minus

String[] result_minus = minus(arr1, arr2);

System.out.println("求差集的结果如下：");

for (String str : result_minus) {

System.out.println(str);

}

}

//求两个字符串数组的并集，利用set的元素唯一性

public static String[] union(Object[] arr1, Object[] arr2) {

Set<String> set = new HashSet<String>();

for (Object str : arr1) {

set.add(str.toString());

}

for (Object str : arr2) {

set.add(str.toString());

}

String[] result = {};

return set.toArray(result);

}

//求两个数组的交集

public static List intersect(Object[] arr1, Object[] arr2) {

Map<String, Boolean> map = new HashMap<String, Boolean>();

LinkedList<String> list = new LinkedList<String>();

for (Object str : arr1) {

if (!map.containsKey(str)) {

map.put(str.toString(), Boolean.FALSE);

}

}

for (Object str : arr2) {

if (map.containsKey(str)) {

map.put(str.toString(), Boolean.TRUE);

}

}

for (Entry<String, Boolean> e : map.entrySet()) {

if (e.getValue().equals(Boolean.TRUE)) {

list.add(e.getKey());

}

}

return list;

}

//求两个数组的差集

public static String[] minus(String[] arr1, String[] arr2) {

LinkedList<String> list = new LinkedList<String>();

LinkedList<String> history = new LinkedList<String>();

String[] longerArr = arr1;

String[] shorterArr = arr2;

//找出较长的数组来减较短的数组

if (arr1.length > arr2.length) {

longerArr = arr2;

shorterArr = arr1;

}

for (String str : longerArr) {

if (!list.contains(str)) {

list.add(str);

}

}

for (String str : shorterArr) {

if (list.contains(str)) {

history.add(str);

list.remove(str);

} else {

if (!history.contains(str)) {

list.add(str);

}

}

}

String[] result = {};

return list.toArray(result);

}

}