Invert Concordance Using Java

Invert Concordance Using Java

today I'm working with a client that creates a concordance from a text
file using Java. All I need to do is invert the concordance to essentially
recreate the text from start to finish. Now, the issue I seem to be having
is where to start and how to do each step. As of now I have tried to
create an array of words and iterate through my symbol table and assign
each key to the array. Then I end up getting just a list of words from the
concordance. For some reason this problem makes me feel very stupid
because it seems like it should be a simple solution. I can't seem to
think of any valid ideas to get me started with recreating the story. I
have included the source here:
public class InvertedConcordance {
public static ST<String, SET<Integer>> createConcordance (String[] words) {
ST<String, SET<Integer>> st = new ST<String, SET<Integer>>();
for (int i = 0; i < words.length; i++) {
String s = words[i];
if (!st.contains(s)) {
st.put(s, new SET<Integer>());
}
SET<Integer> set = st.get(s);
set.add(i);
}
return st;
}
public static String[] invertConcordance (ST<String, SET<Integer>> st) {
//This is what I have so far
//Here is what I have that doesnt work
for(String key : st.keys())
{
inv[i++] = key;
}
for(int z = 0; z< inv.length; z++)
{
System.out.println(inv[z]);
}
String[]inv = new String[st.size()];
return inv;
}
private static void saveWords (String fileName, String[] words) {
int MAX_LENGTH = 70;
Out out = new Out (fileName);
int length = 0;
for (String word : words) {
length += word.length ();
if (length > MAX_LENGTH) {
out.println ();
length = word.length ();
}
out.print (word);
out.print (" ");
length++;
}
out.close ();
}
public static void main(String[] args) {
String fileName = "data/tale.txt";
In in = new In (fileName);
String[] words = in.readAll().split("\\s+");
ST<String, SET<Integer>> st = createConcordance (words);
StdOut.println("Finished building concordance");
// write to a file and read back in (to check that serialization works)
//serialize ("data/concordance-tale.txt", st);
//st = deserialize ("data/concordance-tale.txt");
words = invertConcordance (st);
saveWords ("data/reconstructed-tale.txt", words);
}
}