Passing functions as parameters?

[greedyzebra]

Hi,

I know that in JavaScript you can assign reference to a function and access it's members like any other object, but can this be done with Java? And if so, what would be its functionality?

My situation is this: I'm wanting a function that will call multiple functions. The issue is how to decide which of those functions to call. While it is possible to use a switch statement and call the appropriate function based on a "key" provided as a parameter, there are many possible functions and the number of "cases" would be prohibitive.

If there is some way to reference a function call, then perhaps I could call the function with that reference after the reference has been passed as a parameter.

I'm sure there are other ways to achieve this that I haven't thought of... any suggestions are welcome.

Thanks!

 

[palbano]

>> can this be done with Java?

No.

>> any suggestions are welcome

Java is Object Oriented so first, stop thinking from a “function” standpoint. It sounds like you could use an interface and then several objects that implement that interface to provide different implementations of it.

The interface might declare a single function then you can have multiple classes that implement the interface. Each instance of those classes can be passed to a function that takes the “interface” type as a parameter

 interface foo{
	public abstract int getInt(String data);
}

class MyFoo implements foo{
	public int getInt(String data){
		return data.length();
	}
}

class UrFoo implements foo{
	public int getInt(String data){
		return data.length() / 2;
	}
}

class TheMain{
	protected static void HereIsAfoo(foo f){
		System.out.println("foo: " + f.getInt("Hello"));
	}
	
	public static void doit(){
		HereIsAfoo( new UrFoo());
		HereIsAfoo( new MyFoo());
	}
}

-pete