在文档中找到的单词索引-Java

Question

I am trying to write a program that takes in a text file as input, retrieves the words, and outputs each word with each line number that they are located in. I'm having a lot of trouble with this project, although I've made some progress...

So far I have an ArrayList which holds all of the words found in the document, without punctuation marks. I am able to output this list and see all the words in the text file, but I do not know where to go from here... any ideas?

example:

myList = [A, ACTUALLY, ALMOST,....]

I need to somehow be able to associate each word with which line they came from, so I can populate a data structure that will hold each word with their associated line number(s).

I am a programming novice so I am not very familiar with all the types of data structures and algorithms out there... my instructor suggested I use a dynamic multilinked list but I don't know how I would implement that verses ArrayLists and arrays.

Any ideas would be greatly appreciated. Thanks!

Answer 1

You should use a hash table. A hash table is a key/value pair. The key can be every word in the text file, the value, an array list containing the line numbers.

Basically, loop through every word in the text file. If that word is not in your list of words, add it as the key and the line number as the value in a list into the hash table. If that word is already in the table, append the line number to the array list.

Java has good docs on a hash table here

for you to get the methods you need.