Java求字符串数组交集、并集和差集

//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);
}