## 測試數(shù)據(jù)
List<String> words = Arrays.asList("a", "b", "c", "d", "a", "d");

## 具體方法
List<String> results = HashMultiset.create(words).entrySet().stream()
                .filter(w -> w.getCount() > 1)
                .map(Multiset.Entry::getElement)
                .collect(Collectors.toList());
System.out.println(results);

## 結果輸出
-- [a, d] --

/**
 * list集合中獲取重復元素
 * @param list
 * @param <E>
 * @return
 */
public static <E> List<E> getListDuplicateElements(List<E> list){
        List<E> words = list;
        Set<E> repeated = new HashSet<>();
        List<E> results = new ArrayList<>();
        for (E word : words) {
            if (!repeated.add(word)) {
                results.add(word);
            }
        }
       return  results;
  }

## 測試數(shù)據(jù)
List<String> str = new ArrayList<>();
        str.add("張三");
        str.add("張三");
        str.add("李四");
        str.add("王五");

## 方法調用
List<String> listDuplicateElements = getListDuplicateElements(str);
System.out.println(listDuplicateElements);

## 結果輸出
-- [張三] --