How can a HashMap consist only of one entry/object?

Question

I would like to have a HashMap with only one key-value object.

I have created the following HashMap:

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

In the HashMap I would like to have only one entry/object. The key type is an Integer. The value type is a String.

e.g. = <1,"foo.txt">

Every time I find a specific word in a file I would like to

1. Increment the counter in key

2. Add the new file in the value

e.g. Let's say that I'm searching for the word "Hello" in a DocsCollection, I have to store for every appearance of the word "Hello" the term frequency and concatenate the new file to the previous value.

<3,"foo.txt,hello.txt,test.txt">

3 means that I've found the word "Hello" in three files.

and the Value consists of the files where the word was found

If I use the method put, a new entry is created in the HashMap cause the key changes. It's not stable. It begins with "1" but when I find the word second time , the key increments and then the put method inserts a new entry with a new key But i would like to have only one entry and modify the key. Can this be done? How can i have only one object in a HashMap and modify the key every time?

   DocsCollection.put(2,"foo.txt,hello.txt"); 

Thanks, in advance

Answer 1

Try this way:

DocsCollection = Collections.singletonMap(2, "foo.txt,hello.txt");

this Map can't be modified, if you want to to that just do this:

DocsCollection = Collections.singletonMap(3, "foo.txt,hello.txt");

Answer 2

The Map approach might not be the best. The issue is you are changing your key value.

Note it might be better to just have a List<String>, and everytime you match the word, just add the file to the list. You can get the count easily with list.size()