List all the classes used - compile time

Question

Is there any way to make java compiler list all the classes used in the compiled source code?

For example, for code:

import foo.bar.Hello;
import java.util.List;

...

Hello hello = ...
String string = ...
List list = ...

I would like to get

java.lang.String
java.util.List
foo.bar.Hello

Edit

• I want it at compile time (or after compilation finishes), not runtime.

Related

• Obtaining a list of all classes used while running a Java application? is related, but it is about runtime, and I don't want to run the program, just compile.

• Java find out what imports a .class has

Answer 1

During the compilation is not possible. You will have two choices close to the idea:

• use a program which print the imports after class compilation. You can write one using BCEL for instance.

• if you're only interested by the annotation, you can try to add an annotation processor during compilation using APT.

Answer 2

Get all the declared fields. It will return you a Field array from where you can get your desired information about the fields such as field type, field name, filed modifier etc.

For more info read about Field JavaDoc

Try this simple code

    Class<?> clazz = null;
    try {
        clazz = Class.forName("com.x.y.z.ClassName");

        for (Field field : clazz.getDeclaredFields()) {
            System.out.println(field.getName());
            System.out.println(field.getType());

        }
    } catch (Throwable e) {
        e.printStackTrace();
    }