java如何迭代值为列表的哈希映射的结果?
我创建了一个散列映射,它将组合三个参数的唯一键分组,即customer、sc和admin。我想创建一个带有服务器列表的唯一密钥列表。我已经实现了以下功能:
public static void main(String[] args) {
String items = "customer1^sc1^admin1|server1~" +
"customer1^sc1^admin1|server2~" +
"customer1^sc1^admin1|server3~" +
"customer2^sc1^admin1|server1~" +
"customer3^sc1^admin1|server3~" +
"customer3^sc1^admin1|server2~";
// Set up raw data
List<String> splitItems = Arrays.asList(items.split("\\s*~\\s*"));
// Display raw data
System.out.println("Raw List: " + items);
// Create a hash map containing customer name as key and list of logs as value
HashMap<String, List<String>> customerHashMap = new HashMap<>();
// Loop through raw data
for (String item : splitItems) {
// Create new lists. One for customers and one for logs
// List<String> customerList = new ArrayList<>();
List<String> logList;
String list[] = item.split("\\|");
String customer = list[0];
String log = list[1];
logList = customerHashMap.get(customer);
if (logList == null){
logList = new ArrayList<>();
customerHashMap.put(customer, logList);
}
logList.add(log);
// System.out.println(logList);
}
// Print out of the final hash map. Customer "a" should only have "a" logs, customer "b" with "b", etc.
System.out.println("");
List<String> hashMapList = new ArrayList<String>();
Iterator it = customerHashMap.entrySet().iterator();
while (it.hasNext()) {
Map.Entry pair = (Map.Entry) it.next();
String output = pair.getKey() + "|" + pair.getValue().toString();
hashMapList.add(output);
it.remove();
}
String hashMapResultString = hashMapList.toString();
String hashMapResultFormatted = hashMapResultString.replaceAll("[\\[\\]]", "");
System.out.println(hashMapResultFormatted);
}
原始列表:customer1^sc1^admin1|server1~customer1^sc1^admin1|server2~customer1^sc1^admin1|server3~customer2^sc1^admin1|server1~customer3^sc1^admin1|server3~customer3^sc1^admin1|server2~
哈希映射字符串:
customer2^sc1^admin1|server1, customer3^sc1^admin1|server3, server2, customer1^sc1^admin1|server1, server2, server3
现在我想使用哈希映射创建一个字符串,该字符串将被进一步解析(不要问lol)。因此,我将哈希映射的键和值设置为一个字符串,该字符串用唯一的分隔符|
分隔它们。问题是,因为键是一个List<String>
,所以在打印时,如果每个新的key
的值是一个包含多个项的列表,我无法确定它的开头,即customer3^sc1^admin1|server3, server2,
后面紧跟着customer1^sc1^admin1|server1, server2, server3
。我需要一个分隔符来分隔它们
我的理想输出如下所示:
customer2^sc1^admin1|server1~customer3^sc1^admin1|server3, server2~customer1^sc1^admin1|server1, server2, server3~...
我怎样才能做到这一点
更新:
这是我最终发现对我的特定问题有用的答案:
StringBuilder s = new StringBuilder();
for (Map.Entry<String, List<String>> entry : customerHashMap.entrySet()) {
s.append(entry.getKey() + "|");
List<String> list = entry.getValue();
for (String item : list) {
if (item != list.get(list.size() - 1)) {
s.append(item + "^");
} else {
s.append(item);
}
}
s.append("~");
}
System.out.println(s.toString());
# 1 楼答案
可以遍历地图的条目集:
为了更清晰的示例,我输出了与您要求的格式不同的格式,但这说明了如何使用列表值的映射。当适应你的需求时,看看
java.util.StringJoiner
和相关的Collectors.joining()
;这可能很有用溪流在这里很方便:
这里发生的是:
Entry<String,List<String>
流entry -> ...
将每个条目转换为形式为val1^v2^v3^...^valN|key
的字符串,即我们将Stream<Entry<>>
映射为Stream<String>
李>collect()
使用~
作为分隔符将字符串流连接成单个字符串李>