Question

I’m writing a program in Java and I have a method with a header such as public void doSomething(Object o) and I want to check if o is the appropriate type for a parameter of another method. So what I have is:

public void doSomething(Object o)
{
    Method m = //get method of another method (using reflection)
    Class<?> cl = m.getParameterTypes()[0];  //Get the class of the 0th parameter
    if(o instanceof cl)         //compile error here
         //do something
}

However this doesn’t work. Can someone help please. Thanks

Answer 1

instanceof takes a static type as a parameter, what you’re looking for is a dynamic check if o will work as a parameter to the method;

Object o = ...
Method m = ...
Class cl = m.getParameterTypes()[0];
if(cl.isAssignableFrom(o.getClass()))  // Is an 'o' assignable to a 'cl'?
{
}