Getting classes from variables in Java

Question

I'm making a small (for fun) game where virtual robots fight each other. I have an array of names of the classes of these robots, but I don't know how to load them. It's probably clearer in codes:

String[] classes={"Bot1","Bot2","Bot123"};
Object[] bots=new Object[classes.length];

for(int i=0;i<classes.length;i++){
  bots[i]=UnknownFunction(classes[i]);
}

Additional details:

package Arena;

public class Bot {
    public void main(String args[]){

    }

    public void init(){
        System.out.print("Loaded");
    }
}

In the main file:

bot=Class.forName("Arena.Bot").newInstance();
bot.init();

Do you want to get to a Class object like the one you get from String.class or do you want an instance of that class like in new String()? — zapl
– zapl, Commented Nov 22, 2012 at 21:21

Rohit Jain · Accepted Answer · 2012-11-22 21:19:21Z

1

You need Class.forName() method to load your class, and then newInstance() method to instantiate them. Assuming that you have a 0-arg constructor in them: -

bots[i] = Class.forName(classes[i]).newInstance();

Also note that, those class names has to be fully qualified names.

answered Nov 22, 2012 at 21:19

Rohit Jain

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9 Comments

Leo Jiang Over a year ago

Thanks for your response. How would I get the fully qualified names?

Rohit Jain Over a year ago

@Linksku.. That you would have to give. Fully qualified class names means package.subpackage.classname. For e.g: - pkg1.YourClass.

Leo Jiang Over a year ago

I think I've managed to load the classes (try/catch does not return any errors), but I'm unable to run any methods in the classes. I always get "The method init() is undefined for the type Object".

Rohit Jain Over a year ago

@Linksku.. What method are you invoking? Can you post the code? Edit your question to add it.

Leo Jiang Over a year ago

I edited the question. I'm trying to run init(), but it always returns an error.

|

Eng.Fouad · Accepted Answer · 2012-11-22 21:21:27Z

0

String[] classes = {"Bot1", "Bot2", "Bot123"};
Object[] bots = new Object[classes.length];

for(int i = 0; i < classes.length; i++)
{
    bots[i] = Class.forName(classes[i]).newInstance();
}

answered Nov 22, 2012 at 21:21

Eng.Fouad

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