Programming Forums > Application Development > Java

Writlaus · Jan 4th, 2006, 2:29 AM

Is there any way to copy a class or method to another variable (Not create an instance of that class)? The reason I ask is because I want to create a list of methods from which I can choose randomly.

xavier · Jan 4th, 2006, 3:33 AM

I'm not sure if i get it, but you could create a class with static methods. So you could use it like: MyClass.MyMethod;

Darkhack · Jan 4th, 2006, 4:37 AM

I am not 100% clear on your question, but you said you wanted to be able to choose a method at random. Well you can either use an object or static methods. And simply have a random number generator and use a switch statement on it. I am not a Java programmer so I can't tell you how to do a random number generator but there are a billion tutorials for it, just google for it, and it will surely come up. Here is an example once you have your random number...

(Toggle Plain Text)

switch(randomNumber)
{
	case 1: Class.MethodOne();
	case 2: Class.MethodTwo();
	case 3: Class.MethodThree();
}

Arevos · Jan 4th, 2006, 6:17 AM

Quote:

Originally Posted by Writlaus

Is there any way to copy a class or method to another variable (Not create an instance of that class)? The reason I ask is because I want to create a list of methods from which I can choose randomly.

If you know which methods you wish to randomly choose from before runtime, then you can use Darkhack's approach. If you wish to randomly choose from a list of methods that are only decided at runtime, then you need to take a different approach.

You can use anonymous classes to wrap your functions in. e.g:

(Toggle Plain Text)

methodWrapper = new Runnable() {
    public void run() {
        yourMethod();
    }
};
methodWrapper.run();

The method wrapper object created from the anonymous class can then be stored in a list. I've used the Runnable interface as a base, but you can create your own (in fact, it's probably a better idea, to). For instance, the interface below has an 'invoke' method that takes in a string and outputs a boolean:

(Toggle Plain Text)

interface MethodWrapper {
    boolean invoke(String s);
}

alcdotcom · Jan 4th, 2006, 7:42 AM

This would be a good exercise for a functional programming language.

From a design point-of-view, the strategy design pattern might fit the bill.

Arevos · Jan 4th, 2006, 8:23 AM

Quote:

Originally Posted by alcdotcom

This would be a good exercise for a functional programming language.

Or indeed any language where functions are first class objects. Pity Java isn't one of those languages, otherwise the solution would be a lot easier.

alcdotcom · Jan 4th, 2006, 3:53 PM

Quote:

Originally Posted by Arevos

Or indeed any language where functions are first class objects. Pity Java isn't one of those languages, otherwise the solution would be a lot easier.

Java and C# have shadowed each other for years. Now that the new version of C# has OCaml-style lambda functions, maybe Java will follow suit.

Arevos · Jan 4th, 2006, 5:01 PM

Quote:

Originally Posted by alcdotcom

Java and C# have shadowed each other for years. Now that the new version of C# has OCaml-style lambda functions, maybe Java will follow suit.

Yep. Here's hoping! C#'s getters and setters look very nice, also.

Klipt · Jan 4th, 2006, 10:08 AM

Even C has function pointers...

Klipt · Jan 5th, 2006, 4:19 AM

How many years? I thought C# was pretty young compared to Java.

Jan 4th, 2006, 2:29 AM	#1
Writlaus Hobbyist Programmer Join Date: Nov 2005 Posts: 149 Rep Power: 4	classes and methods Is there any way to copy a class or method to another variable (Not create an instance of that class)? The reason I ask is because I want to create a list of methods from which I can choose randomly.

Jan 4th, 2006, 3:33 AM	#2
xavier Professional Programmer Join Date: Oct 2004 Location: .ro Posts: 406 Rep Power: 5	I'm not sure if i get it, but you could create a class with static methods. So you could use it like: MyClass.MyMethod; __________________ Don't take life too seriously, it's not permanent !

Jan 4th, 2006, 4:37 AM	#3
Darkhack Hobbyist Programmer Join Date: Dec 2005 Location: Kansas City Posts: 105 Rep Power: 3	I am not 100% clear on your question, but you said you wanted to be able to choose a method at random. Well you can either use an object or static methods. And simply have a random number generator and use a switch statement on it. I am not a Java programmer so I can't tell you how to do a random number generator but there are a billion tutorials for it, just google for it, and it will surely come up. Here is an example once you have your random number... (Toggle Plain Text) switch(randomNumber) { case 1: Class.MethodOne(); case 2: Class.MethodTwo(); case 3: Class.MethodThree(); } switch(randomNumber) { case 1: Class.MethodOne(); case 2: Class.MethodTwo(); case 3: Class.MethodThree(); }

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Jan 4th, 2006, 7:42 AM	#5
alcdotcom Programmer Join Date: Jan 2006 Location: Dallas, TX Posts: 49 Rep Power: 0	This would be a good exercise for a functional programming language. From a design point-of-view, the strategy design pattern might fit the bill.

Jan 4th, 2006, 10:08 AM	#9
Klipt Hobbyist Programmer Join Date: Dec 2005 Posts: 118 Rep Power: 0	Even C has function pointers...

Jan 5th, 2006, 4:19 AM	#10
Klipt Hobbyist Programmer Join Date: Dec 2005 Posts: 118 Rep Power: 0	How many years? I thought C# was pretty young compared to Java.

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Programming Forums > Application Development > Java

classes and methods