使用HashMap来计算实例

问题描述

我有以下代码来计算数组中不同字符串的实例：

I have the following code to count the instances of different strings in an array;

String words[] = {"the","cat","in","the","hat"};
HashMap<String,Integer> wordCounts = new HashMap<String,Integer>(50,10);
for(String w : words) {
    Integer i = wordCounts.get(w);
    if(i == null) wordCounts.put(w, 1);
    else wordCounts.put(w, i + 1);
}

这是做这件事的正确方法吗？对于一项简单的任务似乎有点冗长。 HashMap 结果对我很有用，因为我会用字符串对它进行索引。

Is this a correct way of doing it? It seems a bit long-winded for a simple task. The HashMap result is useful to me because I will be indexing it by the string.

我很担心line

I am worried that the line

else wordCounts.put(w, i + 1);

可以插入第二个键值由于这样的事实：

could be inserting a second key-value pair due to the fact that

new Integer(i).equals(new Integer(i + 1));

会是假的，所以两个整数会最终在同一个字符串键桶之下，对吧？或者我只是想自己到了一个角落？

would be false, so two Integers would end up under the same String key bucket, right? Or have I just over-thought myself into a corner?

推荐答案

是的，你正在做正确的做法。如果提供了相同的密钥，HashMap将替换值。

Yes you are doing it correct way. HashMap replaces values if same key is provided.

从Java文档

From Java doc of HashMap#put

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