java 查找list中重复数据

查找一个List集合中所有重复的数据，重复的数据可能不止一堆，比如：aa, bb, aa, bb, cc , dd, aa这样的数据。如果有重复数据，则给这些重复数据加上编号，上述数据改为：aa1, bb1, aa2, bb2, cc, dd.

算法如下：

public static void same(List<String> list) {
    String [] indexArr ;
    Map<String, String> map = new HashMap<String, String>();
    for (int i = 0; i < list.size(); i++) {
      String key = list.get(i);
      String old = map.get(key);
      if (old != null) {
        map.put(key, old + "," + (i + 1));
      } else {
        map.put(key, "" + (i + 1));
      }
    }
    Iterator<String> it = map.keySet().iterator();
    int index = -1;
    while (it.hasNext()) {
      String key = it.next();
      String value = map.get(key);
      if (value.indexOf(",") != -1) {
        System.out.println(key + " 重复,行： " + value);
        indexArr = value.split(",");
 
        for (int i = 0; i < indexArr.length; i++) {
          index = Integer.parseInt(indexArr[i])-1;
          list.set(index, list.get(index)+(1+i));
        }
      }
    }
 
    for (String val : list) {
      System.out.println("val = "+val);
    }
    System.out.println("..................");
 
  }

Java遍历Map效率对比

https://blog.csdn.net/whgyxy/article/details/88806090