Find out which classes of a given API are used

Question

In a Java Project of mine, I would like to find out programmatically which classes from a given API are used. Is there a good way to do that? Through source code parsing or

Answer 1

Something like this perhaps:

import java.io.*;
import java.util.Scanner;
import java.util.regex.Pattern;

public class FileTraverser {

    public static void main(String[] args) {
        visitAllDirsAndFiles(new File("source_directory"));
    }

    public static void visitAllDirsAndFiles(File root) {
        if (root.isDirectory())
            for (String child : root.list())
                visitAllDirsAndFiles(new File(root, child));
        process(root);
    }

    private static void process(File f) {

        Pattern p = Pattern.compile("(?=\\p{javaWhitespace}*)import (.*);");
        if (f.isFile() && f.getName().endsWith(".java")) {
            try {
                Scanner s = new Scanner(f);
                String cls = "";
                while (null != (cls = s.findWithinHorizon(p, 0)))
                    System.out.println(cls);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
    }
}

You may want to take comments into account, but it shouldn't be too hard. You could also make sure you only look for imports before the class declaration.