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FirewolfTheBrave
FirewolfTheBrave wrote ...

2021/3/29

Using a variable in place of a class name in a method

FirewolfTheBrave FirewolfTheBrave

2021/3/29

#
I'm trying to write a method that can quickly add a given amount of objects from a given class on random free spaces on the map. For this, I've come up with the following code: 
public void place (int amount, Class objectType)
    {
        for (int i = 0; i < amount; i++)
        {
            objectType placeThis = new objectType;   //This is the problematic line
            int x, y;
            do {
                x = Greenfoot.getRandomNumber (getWidth());
                y = Greenfoot.getRandomNumber (getHeight());
            } while (getObjectsAt (x, y, Actor.class).size() != 0);
            addObject (placeThis, x, y);
        }
    }
The problem: The compiler won't accept "objectType" as a valid class for the new object, even though its type is Class. How can I fix this?
danpost danpost

2021/4/2

#
One way to instantiate a class is something like this: 
Actor placeThis = null;
try { placeThis = objectType.newInstance(); }
catch (Exception e) { break; }
This is to replace line 5. The break statement should exit the for loop should a problem arise during instantiation of the class.
FirewolfTheBrave FirewolfTheBrave

2021/4/3

#
I did need to do an additional typecasting in your second line (bc Object != Actor), but overall, it worked. Thank you!
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