gistfile1.txt

interface Command { 
  void execute(); 
}

interface DrawLineCommand extends Command { }

interface DrawBoxCommand extends Command { }

Command drawALine() {
  return ()->doLineDrawing();
}

Command drawABox() {
  return ()->doBoxDrawing();
}

I want to return an instance of DrawLineCommand from drawALine and DrawBoxCommand from drawABox

Obviusly I can not use lamdas, and just do new DrawLineCommand() { void execute() {...}}; etc

I would do it this way:

    static interface Command {

        void execute();
    }

    static interface DrawLineCommand extends Command {
    }

    static interface DrawBoxCommand extends Command {
    }

    static DrawLineCommand drawALine() {
        return () -> System.out.println("drawALine");
    }

    static DrawBoxCommand drawABox() {
        return () -> System.out.println("drawABox");
    }

    static List<Command> renderSomething() {
        List<Command> commands = new ArrayList<>();
        commands.add(drawALine());
        commands.add(drawABox());
        return commands;
    }

    @Test
    public void testMatteo() {
        for (Command command : renderSomething()) {
            System.out.println(command instanceof DrawLineCommand);
            System.out.println(command instanceof DrawBoxCommand);
        }
    }