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I need to call the main method of a Java class from another main method using reflection.
Usage of reflection is a must so as to remove compile time dependency of the main class being called. Straightforward approach is not yielding as it recognizes only 'public' and 'non-static' method. Suggestions?
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Call a Method Inside main , call the myMethod() method: public class Main { static void myMethod() { System.out.println("I just got executed!"); } public static void main(String[] args) { myMethod(); } } // Outputs "I just got executed!"
First, to find the main() method the code searches for a class with the name "main" with a single parameter that is an array of String Since main() is static , null is the first argument to Method. invoke() . The second argument is the array of arguments to be passed.
Solution: Though Java doesn't prefer main() method called from somewhere else in the program, it does not prohibit one from doing it as well. So, in fact, we can call the main() method whenever and wherever we need to.
Shouldn't be any more complicated than calling any other function:
public static void main(String[] args) throws ClassNotFoundException, SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException { Class<?> cls = Class.forName("pkg1.pkg2.classname"); Method meth = cls.getMethod("main", String[].class); String[] params = null; // init params accordingly meth.invoke(null, (Object) params); // static method doesn't have an instance } But I don't really see many uses for that, the only thing it buys you is that you can compile the program without linking the other one as long as you never use that specific code path, but if that's what you need, here we go ;)
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