CODEWITHSUNDEEP
javainheritance
user3029760
user3029760

Reputation: 185

Trying to use subclass method but it is not letting me

So say I have 3 classes, Tester, Fruit (superclass), and Apple (subclass)

I have written a new method in Apple (which extends Fruit). The method being:

public String getAppleColor()

Now say in Tester I have created an array of 10 Fruit

Fruit fruitArray = new Fruit[10]

and say I make one of them

fruitArray[3] = new Apple()

This is fine, since Apple is also of type Fruit. However I wish to use my getAppleColor() on this specific element of the array:

String appleColor = fruitArray[3].getAppleColor();

How come this is not working? When I look at useable methods on fruitArray[3] in eclipse, none of my Apple methods show up, but I made fruitArray[3] an Apple?

Upvotes: 0

Views: 145

Answers (4)

mojiayi
mojiayi

Reputation: 187

You'd better declare a method getColor() in class Fruit, override it in subclass Apple, then you can get color of apple by fruitArray[3].getColor().

Upvotes: 1

Lord M-Cube
Lord M-Cube

Reputation: 361

You have to cast it to an Apple since the compiler won't know that fruitArray[3] will contain an Apple (it might contain any other sort of Fruit). Try:

String appleColor = ((Apple)fruitArray[3]).getAppleColor();

Upvotes: 2

Sotirios Delimanolis
Sotirios Delimanolis

Reputation: 279880

The compiler cannot know that at runtime, an element declared as a Fruit is actually an Apple. As such, it won't let you call any methods declared in Apple.

Your array is 

Fruit[] fruitArray;

The compiler can only know that the elements in the array are Fruit instances, nothing more.

Upvotes: 1

Jigar Joshi
Jigar Joshi

Reputation: 240860

You can't call getAppleColor() on Fruit reference, it doesn't declare that method

better design would be have getFruitColor() defined and make Fruit abstract class / make it interface and force each Fruit implement this method

Compiler doesn't know what implementation it is going to be assigned at runtime

Upvotes: 2

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