Table Data Type

[sehudson]

I am reading in a file char by char and keep a count of the number of occurences of each letter, and need to come up with a way to save the data in a Table ADT. I didnt think there was a table data type. How can I represent the data as a table?

[Fubarable]

What is a "Table ADT"? What specifically are your requirements?

Edit: For what it's worth, normally, I'd store this frequency data in a HashMap<Character, Integer>.

[sehudson]

not an ADT, sorry. The characters and their counts will be kept in a table data structure.

[sehudson]

so the characters would be the 'keys' of the map?

[Fubarable]

so the characters would be the 'keys' of the map?

Yes. And the value would be the count of occurrences.

[sehudson]

Ok, so if I do a myHashMap.put(A,1) for the first time I find an A, how would I update the value portion (the 1) the next time I find an A?

[Fubarable]

First you'd call get on the HashMap using your char as a key. If it returns null, then you know that this is the first time that this char was encountered and you'd put in a 1 for this char. Otherwise if it returns a viable Integer, you get the intValue, add one to it, and put the resulting incremented value.

[sehudson]

hmm.. looks like get is returning an object. Is it as simple as casting it to an int?

[sehudson]

nevermind, I see what what you are saying

[Fubarable]

hmm.. looks like get is returning an object. Is it as simple as casting it to an int?

No, try it and you'll see what happens if you try to cast a reference type to a primitive. You should be using a generic HashMap<Character, Integer>. So get will return an Integer. You get an int from this by calling intValue on the Integer returned, or you could just use it as is via auto-unboxing.

[sehudson]

so it would be like:

HashMap table = new HashMap<Character,Integer>;

[Fubarable]

so it would be like:

HashMap table = new HashMap<Character,Integer>;

No, and you might want to have a look at the generics tutorial in the Oracle Java tutorials. The HashMap declaration, the left hand side of this expression is also generic.

[sehudson]

Ok..now I have to add the characters into a 'min heap' according to frequency? I guess I can iterate over the HashMap, but I have not worked with a min heap