How does one access a method from an external jar at runtime?

Question

This is a continuation of the question posted in: How to load a jar file at runtime

I am uncertain as to how to continue to the method invocation level. From my und

Answer 1

Here is some reflection code that doesn't cast to an interface:

public class ReflectionDemo {

  public void print(String str, int value) {
    System.out.println(str);
    System.out.println(value);
  }

  public static int getNumber() { return 42; }

  public static void main(String[] args) throws Exception {
    Class clazz = ReflectionDemo.class;
    // static call
    Method getNumber = clazz.getMethod("getNumber");
    int i = (Integer) getNumber.invoke(null /* static */);
    // instance call
    Constructor ctor = clazz.getConstructor();
    Object instance = ctor.newInstance();
    Method print = clazz.getMethod("print", String.class, Integer.TYPE);
    print.invoke(instance, "Hello, World!", i);
  }
}

Writing the reflected classes to an interface known by the consumer code (as in the example) is generally better because it allows you to avoid reflection and take advantage of the Java type system. Reflection should only be used when you have no choice.