黑豹程序员-字符串中查找出重复的字符串

Collections.frequency(codeList, element)
字符串element，在codeList集合中重复的次数。

List<String> repList = new ArrayList<>();
for (String element : codeList) {
    if (Collections.frequency(codeList, element) > 1 && Collections.frequency(repList, element) ==0) {
        repList.add(element);
    }
}