App.java

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;

import difflib.Delta;
import difflib.DiffUtils;
import difflib.Patch;

import static java.lang.Math.abs;

public class App {
    private static List<String> fileToLines(String filename) {
        List<String> lines = new LinkedList<String>();
        String line = "";
        try {
            BufferedReader in = new BufferedReader(new FileReader(filename));
            while ((line = in.readLine()) != null) {
                lines.add(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return lines;
    }

    private static boolean isImportant (Delta d) {

        String original = d.getOriginal().getLines().toString();
        String revised = d.getRevised().getLines().toString();

        int max = original.length() > revised.length()? original.length() : revised.length();

        String[] splitO = original.split("\\W+");
        String[] splitR = revised.split("\\W+");

        int lngth;
        String longer;
        String shorter;
        int counter;

        if(splitO.length != splitR.length) return true;
        for (int i= 0; i < splitO.length; i++){
            if (!splitO[i].equals(splitR[i])){
                if(abs(splitO[i].length() - splitR[i].length()) > 2) return true;
                if(splitO[i].length() > splitR[i].length()){
                    longer = splitO[i];
                    shorter = splitR[i];
                    lngth = splitO[i].length();
                }
                else {
                    longer = splitR[i];
                    shorter = splitO[i];
                    lngth = splitR[i].length();
                }
                counter = 0;
                for (int j = 0, k = 0; j < lngth; j++, k++){
                    if (longer.charAt(j) != shorter.charAt(k)) {
                        k--;
                        counter++;
                    }
                }
                if (counter > 2){
                    System.out.println(longer + "\n" + shorter);
                    return true;
                }
            }
        }
        return false;
    }
    public static void main(String[] args) {
        List<String> original = fileToLines(args[0]);
        List<String> revised  = fileToLines(args[1]);

        Patch patch = DiffUtils.diff(original, revised);

        for (Delta delta : patch.getDeltas())
            if(isImportant(delta)) System.out.println("Difference: " + delta.getOriginal().getLines() + delta.getRevised().getLines());
    }
}