Find classes in a package

Question

I'm new to java. What's the best way to find all classes in a standard package (e.g. java.awt). I'm trying to create a list for classes in a package in java.
thanks

Answer 1

I guess you're talking about finding them in a running program (like scanning).
Well, I'm searching a solution for a similar problem.
Unfortunately, java classes are loaded on demand. That is, if you're not using kung.foo.MyClass in your code, its not known by the vm, so you can't find it using VM calls.
Since this behavior is the same for packages, you can test this behavior if you're scanning packages using Package.getPackages():
public class PackageTester {
  // drops the package info on screen.
  public static void listAll (String message , Package [] data) {
    System.out.println ( ) ;
    System.out.println ( message) ;
    System.out.println ( "Amount of passed classes : "+data.length) ;
    for (int i = 0 ; i < data.length; i++)
          System.out.println ( data.toString()) ;
public static void main (Strinbg [] args) {
// get a list of all known packages
Package [] state1 = Package.getPackages() ;
// load a yet unknown class
MyClass kong.foo.myClass = new kong.foo.MyClass () ;
// reload all packages
Package [] state2 = Package.getPackages() ;
// print lists to screen
listAll ("packages before loading MyClass" , state1) ;
listAll ("packages after loading MyClass" , state2) ;
Didnt check, but the code should compile.
This means that, if you want to scan for classes in the vm, you'll have to say the vm which classes you're scanning for. Of course, this is nonsense.
The most complete way is to scan all files starting at the classpath-entries, and looking for .class-files in directories and .jar/.zip-files. This is much work to do, but it seems to be the only useful solution to solve this nasty problem. You could use tools, which surely are available; but its not an elegant solution.
Sorry.