better way for creating multiple instances from children abstract class without using class.newInstance java

I create school project in Greenfoot and I try creating one method which has two parameters, one for numbers of instances and second for a name of a class from which I want to create instances. Here is the concrete code:

private <T extends Actor> void manyActors(int many, Class<T> cls)
    {          
        try
        {
        for(int i=0;i<many;i++)
        {
            addObjectRnd( cls.newInstance() ); 
        }
    }
    catch(InstantiationException e)
    {
        some not important code
    }
    catch(IllegalAccessException e){
       ...
    }

I think this is not a good solution but I can't figure out how this problem solve in another way and possibly better. exist different and possibly better solution or only another option is it using a structure like array or List?