問題描述

我應(yīng)該在另一個 HashMap 中創(chuàng)建一個 HashMap 如下所示，它可以根據(jù)鍵將值存儲在內(nèi)部 HashMap 中運(yùn)行時外層HashMap

I am supposed to created a HashMap inside another HashMap as shown below which can store the value inside the inner HashMap based on the key of the outer HashMap at the runtime

即程序所需的輸出應(yīng)該是格式

i.e. required output for program should be of the format

   { 1 = {11 = "aaa",15 = "bbb"}, 2 = {13 = "ccc", 14 = "ddd"} }

其中 1,2 是 Outer HashMap 的鍵值.

where 1,2 are Key values for Outer HashMap.

下面是為其提供的代碼有沒有更好的方法來提高性能

Below is the Code provided for it Is there any better approach to improve performance

HashMap<Integer, HashMap<Integer, String>>Outer 
                   = new HashMap<Integer, HashMap<Integer,String>>();

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    int count = Integer.parseInt(br.readLine());
    for(int i =0;i<count;i++)
    {
        String input[] = br.readLine().split("\s");

        //HashMap<Integer,String>inner = new HashMap<Integer, String>();
        int key = Integer.parseInt(input[0]);
        if(Outer.isEmpty() || !Outer.containsKey(key))
        {
            HashMap<Integer, String> inner = new HashMap<Integer, String>();
            inner.put(Integer.parseInt(input[1]),input[2]);
            Outer.put(key, inner);
        }
        else if(Outer.containsKey(key))
            {
                HashMap<Integer, String> inner = (HashMap<Integer, String>) Outer.get(key).clone();
                inner.put(Integer.parseInt(input[1]), input[2]);
                Outer.put(key, inner);
            }
    }

推薦答案

類似于 Vadim 的答案，但進(jìn)一步改進(jìn) - 因?yàn)樗恍枰瑫r調(diào)用 containsKey 和 獲取:

Similar to Vadim's answer, but further improved - as it doesn't require a call to both containsKey as well as get:

Map<Integer, Map<Integer, String>> outer = new HashMap<Integer, Map<Integer, String>>();
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int count = Integer.parseInt(br.readLine());

Pattern splitter = Pattern.compile("\s");

for(int i = 0; i < count; i++){
    String input[] = splitter.split(br.readLine());

    int key = Integer.parseInt(input[0]);

    Map<Integer, String> inner = outer.get(key);
    if(inner == null){
        inner = new HashMap<Integer, String>();
        outer.put(key, inner);
    }
    inner.put(Integer.parseInt(input[1]), input[2]);
}

它還對命名約定以及使用 Collections 接口而不是具體類型進(jìn)行了一些小的改進(jìn).

It also has some minor improvements for naming conventions, and use of the Collections interfaces instead of concrete types.

我還刪除了對 clone 的調(diào)用.這可能會節(jié)省一點(diǎn)點(diǎn) - 我認(rèn)為它不會給您帶來預(yù)期的結(jié)果.

I also removed the call to clone. This could be a slight savings - and I don't think it would have given you your expected results.

最后 - 我更改的另一件事可能會略有改進(jìn)，即使用預(yù)編譯模式將字符串拆分為字段.

Finally - one other thing that I changed that could be a slight improvement is using a pre-compiled Pattern for the splitting of your String into fields.

這篇關(guān)于將 HashMap 存儲在另一個 HashMap 中并提高性能的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！