cant retrieve data.

[ken zemaitis]

Hi everyone. I'm getting the same error while compiling a few of my progams. What is wrong with this: " System.out.println(fruits[i].info());"?

public class CannotCallCorrectly {
  public static void main(String[] args) {
    Object[] fruits = new Object[0];
    fruits[0] = new Fruit();
    fruits[1] = new Apple();
    fruits[2] = new Banana();
    for (int i = 0; i < fruits.length; i++) {
      if (fruits[i] != null)
        System.out.println(fruits[i].info());
    }
  }
}
class Fruit {
  public String info() {
    return "I'm a fruit.";
  }
}
class Banana extends Fruit {
  public String info() {
    return "I'm a banana. Remove peel before eating.";
  }
}
class Apple extends Fruit {
  public String info() {
    return "I'm an apple. Don't swallow the seeds.";
  }
}

Thanks.

[marc weber]

When you put (references to) your Fruit objects into an Object array, the reference type is upcast to Object. So when you get it back out, you need to explicitly downcast it back to Fruit.

[fred rosenberger]

It would help in the future if you posted the exact error message...

but, i think what the problem is is that you have an array of Objects. your reference is of type Object, not of type Fruit. so, there is no such thing as Object.info().

in other words, since fruits is declared as an Object reference, you can only call Object methods.

if you make it

Fruit[] fruits = new Fruits[0];

you'll find a brand new problem to fix!!! (how big is the array you're declaring???)

[ken zemaitis]

Originally posted by fred rosenberger:
It would help in the future if you posted the exact error message...

but, i think what the problem is is that you have an array of Objects. your reference is of type Object, not of type Fruit. so, there is no such thing as Object.info().

in other words, since fruits is declared as an Object reference, you can only call Object methods.

if you make it

Fruit[] fruits = new Fruits[0];

you'll find a brand new problem to fix!!! (how big is the array you're declaring???)

Next time I will definitely post the exact error message. Thank you for taking the time to look at my problem and thank you for HELPING me figure it out. Something just clicked...

[ken zemaitis]

Originally posted by marc weber:
When you put (references to) your Fruit objects into an Object array, the reference type is upcast to Object. So when you get it back out, you need to explicitly downcast it back to Fruit.

Thank you again sir. I appreciate your wisdom.