Question

I am using a MSDOS to pipe in a file.. I am trying to write a program that counts how many times each word pair appears in a text file. A word pair consists of two consecutive words (i.e. a word and the word that directly follows it). In the first sentence of this paragraph, the words “counts” and “how” are a word pair.

What i want the program to do is, take this input :

abc def abc ghi abc def ghi jkl abc xyz abc abc abc ---

Should produce this output:

abc:
abc, 2
def, 2
ghi, 1
xyz, 1

def:
abc, 1
ghi, 1

ghi:
abc, 1
kl, 1

jkl:
abc, 1

xyz:
abc, 1

BTW: i am excluding “a”, “the”, “and” which has nothing to do with the word pair..

What is the best way to do this? please be nice, I am new to java..
this is what i have so far..

import java.util.Scanner;
import java.util.ArrayList;
import java.util.TreeSet;
import java.util.Iterator;
import java.util.HashSet;

public class Project1
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in); 
        String word;
        String grab;
        int number;

        // ArrayList<String> a = new ArrayList<String>();
        // TreeSet<String> words = new TreeSet<String>();
        HashSet<String> uniqueWords = new HashSet<String>();

        System.out.println("project 1\n");

        while (sc.hasNext()) 
        {
            word = sc.next();
            word = word.toLowerCase();

            if (word.matches("a") || word.matches("and") || word.matches("the"))
            {
            }
            else
            {
                uniqueWords.add(word);
            }

            if (word.equals("---"))
            {
                break;
            }
        }

        System.out.println("size");
        System.out.println(uniqueWords.size());

        System.out.println("unique words");
        System.out.println(uniqueWords.size());

        System.out.println("\nbye...");
    }
}

Sorry about the formatting. Its hard to get it right in here…

Answer 1

What about using a Map:

Map<String, List<String>> words = new HashMap<String, List<String>>();

The keys in the map would be unique words, and the values would each be lists of words that followed that unique word. The data structure might look like:

Key    |    Value
--------------------------
abc    |    def, ghi, jkl
def    |    jkl, mno