java 交集 差集 并集

package com.wish.datastrustudy;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
public class StringArray {
public static void main(String[] args) {
//测试union
String[] arr1 = {"abc", "df", "abc","dd","bdfe"};
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);
}

//测试insect
String[] result_insect = intersect(arr1, arr2);
System.out.println("求交集的结果如下：");
for (String str : result_insect) {
System.out.println(str);
}
//测试 substract
String[] result_minus = substract(arr1, arr2);
System.out.println("求差集的结果如下：");
for (String str : result_minus) {
System.out.println(str);
}
}

//并集（set唯一性）
public static String[] union (String[] arr1, String[] arr2){
Set<String> hs = new HashSet<String>();
for(String str:arr1){
hs.add(str);
}
for(String str:arr2){
hs.add(str);
}
String[] result={};
return hs.toArray(result);
}

//交集(注意结果集中若使用LinkedList添加，则需要判断是否包含该元素，否则其中会包含重复的元素)
public static String[] intersect(String[] arr1, String[] arr2){
List<String> l = new LinkedList<String>();
Set<String> common = new HashSet<String>();
for(String str:arr1){
if(!l.contains(str)){
l.add(str);
}
}
for(String str:arr2){
if(l.contains(str)){
common.add(str);
}
}
String[] result={};
return common.toArray(result);
}
//求两个数组的差集
public static String[] substract(String[] arr1, String[] arr2) {
LinkedList<String> list = new LinkedList<String>();
for (String str : arr1) {
if(!list.contains(str)) {
list.add(str);
}
}
for (String str : arr2) {
if (list.contains(str)) {
list.remove(str);
}
}
String[] result = {};
return list.toArray(result);
}
}