Java实现数组的交集、并集、差集

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/** * 数组交集，并集，差集 * @author Administrator * */public class cal3 {    public static void main(String[] args) {        String[] arr1 = {"abc", "df", "abc"};           String[] arr2 = {"abc", "cc", "df", "d", "abc"};           intersect(arr1, arr2);    }    //并集    public static Set 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);           }          return set;    }    //差集(在数组A中不在数组B中)    public static List<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);                   }               }           }          return list;    }       //交集    public static List<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());                   System.out.println(e.getKey());            }           }           return list;    }   }
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