从不同的类动态调用方法

Question

I have a requirement where in i need to invoke method from class in a particular pattern which is obtained as input argument.

   public RandomMethod(String ClassName){
        //Eg For Class Name Abc , there is a method AbcProcessor which i need to invoke
        ClassName.ClassNameProcessor    
        }

Since i am getting the argument as String , i am not able to figure out how to cast String into a form where i can call something like Abc.AbcProcessor()

I believe there is some way to do this using reflections. But i am not sure how to proceed.

Answer 1

You need to use reflecton, indeed :

public void randomMethod(String fullyQualifiedClassName, String methodName) throws ReflectiveOperationException {
    Class<?> clazz = Class.forName(fullyQualifiedClassName);

    clazz.getMethod(methodName).invoke(null);
}

which would work assuming you are calling public static method with no arguments

Answer 2

By reflection you can do that, try following sample:

Class A:

public class A {
    public void print(){
        System.out.println("A");
    }
}

Class B:

public class B {
    public void print(){
        System.out.println("B");
    }    
}

Invoking print() from A and B:

public class Test {

    public static void callPrint(String className){
        try {
            Class clazz = Class.forName(className);
            Object obj = clazz.newInstance();
            clazz.getDeclaredMethod("print").invoke(obj);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static void main(String[] args) {
        callPrint("test.A");
        callPrint("test.B");
    }
}