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Thread: Help me learn - Polymorphism

  1. #1
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    Question Help me learn - Polymorphism

    Hey, I'm tring to learn Java, but i don't uderstand why I have do this:

    		APFour bucky[] = new APFour[2];
    		//This to define what we should use to call the methods. (bucky[0] and bucky[1] is the names)
    		bucky[0] = new APThree();
    		bucky[1] = new APTwo();
     
    		//This is just to loop thought the methods.
    		for(int x = 0; x<=1; x++){
    			bucky[x].eat();
    		}
    	}

    I don't understand why I have to put APFour[2] and not just APFour();


    My otherclasses:

    One (Sub Class):

    	void eat(){
    		System.out.println("This STARTER is great. ");
    	}

    Two (Sub Class):


    	void eat(){
    		System.out.println("This DINNER is great. ");
    	}


    Three (Super Class):


    	void eat(){
    		System.out.println("This food is great. ");
    	}


    Thanks for your time!


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    Default Re: Help me learn - Polymorphism

    Some things are done simply because that's the right way to do them. In the case of the example you've given, it's done because that's how an array variable is declared. It may make more sense to you if you use the preferred syntax:

    APFour[] bucky = new APFour[2];

    That says, "Create an array variable of type APFour called bucky and size it so that it can contain 2 APFour objects."

    Edit: "size it" means to reserve that much memory for storing those objects.

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