LeetCode--Group Anagrams--Java

Given an array of strings, group anagrams together.

For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"], 
Return:

[
  ["ate", "eat","tea"],
  ["nat","tan"],
  ["bat"]
]

Note:

1. For the return value, each inner list‘s elements must follow the lexicographic order.
2. All inputs will be in lower-case.

Update (2015-08-09):
The signature of the function had been updated to return list<list<string>> instead of list<string>, as suggested here. If you still see your function signature return alist<string>, please click the reload button  to reset your code definition.

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public class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        List<List<String>>result = new ArrayList<>();
        if(strs == null || strs.length == 0)
           return result;
        //将字典序的字符串作为key，将其同位词组转到一个List中存储到HashMap中
        HashMap<String,List<String>>map = new HashMap<>();  

        for(int i = 0; i < strs.length; i++) {
           char[] chars = strs[i].toCharArray();
           // 字典序排序
           Arrays.sort(chars);
           String temp = new String(chars);  

           if (!map.containsKey(temp)) {
               List<String> result_list = new ArrayList<>();
               result_list.add(strs[i]);
               map.put(temp, result_list);
           } else {
               map.get(temp).add(strs[i]);
           }
        }  

        //遍历map，对ArrayList进行字典序排序
        Iterator<Map.Entry<String,List<String>>>iterator = map.entrySet().iterator();
        while(iterator.hasNext()) {
           Map.Entry<String,List<String>> entry = iterator.next();
           List<String> temp_list = entry.getValue();
           Collections.sort(temp_list);
           result.add(temp_list);
        }
        return result;
    }
}  

public class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
       Map<String,ArrayList<String>> map = new HashMap<String,ArrayList<String>>();
       for(String str : strs){
           String sortedstr = Sortstr(str);
           if(map.containsKey(sortedstr)){
               map.get(sortedstr).add(str);
           }
           else{
               map.put(sortedstr,new ArrayList<String>());
               map.get(sortedstr).add(str);
           }
       }
       List<List<String>> result = new ArrayList<List<String>>(map.values());
       for(List<String> res : result){
           Collections.sort(res);
       }
       return result;
    }
    private String Sortstr(String str){
        char[] char1 = str.toCharArray();
        Arrays.sort(char1);
        return new String(char1);
    }
}