java求字符串数组交集、并集和差集

import java.util.HashMap;   
import java.util.HashSet;   
import java.util.LinkedList;   
import java.util.Map;   
import java.util.Map.Entry;   
import java.util.Set;   
  
public class StringArray {   
    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);   
        } 
        //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(String[] arr1, String[] arr2) {   
        Set<String> set = new HashSet<String>();   
        for (String str : arr1) {   
            set.add(str);   
        }   
        for (String str : arr2) {   
            set.add(str);   
        }   
        String[] result = {};   
        return set.toArray(result);   
    }    
    //求两个数组的交集   
    public static String[] intersect(String[] arr1, String[] arr2) {   
        Map<String, Boolean> map = new HashMap<String, Boolean>();   
        LinkedList<String> list = new LinkedList<String>();   
        for (String str : arr1) {   
            if (!map.containsKey(str)) {   
                map.put(str, Boolean.FALSE);   
            }   
        }   
        for (String str : arr2) {   
            if (map.containsKey(str)) {   
                map.put(str, Boolean.TRUE);   
            }   
        }   
  
        for (Entry<String, Boolean> e : map.entrySet()) {   
            if (e.getValue().equals(Boolean.TRUE)) {   
                list.add(e.getKey());   
            }   
        }   
        String[] result = {};   
        return list.toArray(result);   
    }   
    //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);   
    }   
}  

　　

求并集的结果如下：
d
abc
df
cc

求交集的结果如下：
abc
df

求差集的结果如下：
cc
d