查询数组中相同元素的个数

查询数组中相同元素的个数

1.定义一个String数组

String[] txtStrs = ["L","H","C","L","L","L","H","H","C"];

2.创建一个HashMap来存放数组的信息，HashMap的键为元素，值为该元素出现的次数

HashMap<String, Integer> map = new HashMap<String, Integer>();
for(String str:txtStrs){
int i = 1;
if(map.get(str) != null){
i = map.get(str) + 1;
}
map.put(str, i);
}

3.遍历HashMap,获取元素的信息和个数，将其拼接成字符串

Iterator<Entry<String, Integer>> iter = map.entrySet().iterator();
String txtAfterFormat = "";
while (iter.hasNext()) {
Entry<String, Integer> entry = iter.next();
String key = (String) entry.getKey();
int val = (Integer) entry.getValue();
txtAfterFormat = txtAfterFormat + key + "_" + val + ";";
}

4.结果为： L_4;H_3;C_2;