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upcasting and downcasting

I am having the following method: //Number is an abstract class //I am passing an object as a 1.argument and the 2nd argument is the instanzvariable itself public Number addition(Number n) { Realnumb r=(Realnumb)n;//downcasting Number n=new Realnumb(a+r.a); } public String toString() { } Main method: Number n1=new Realnumb(3.0); Number n2=new Realnumb(5.0); System.out.println(n1.addition(n2)); The result should be 8.0. My question is how to call the "toString" method in the method "addition"? As I am having a method of type "Number", what should be the return value?

15th Dec 2019, 9:30 AM
Preet
5 Réponses
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Every object has a toString() method. That's why you can print every object. System.out.println(anyObject) -> calls toString() so you don't need to write System.out.println(anyObject.toString()); Your class RealNumb need to override toString(). public class RealNumb{ private Number n; @Override public String toString{ return n.toString(); } } You can also have a look into this code: https://code.sololearn.com/cK2H7CdVEq45/?ref=app
15th Dec 2019, 1:06 PM
Denise Roßberg
Denise Roßberg - avatar
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https://code.sololearn.com/cF9J5D55GT94/?ref=app
15th Dec 2019, 1:20 PM
Preet
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Can you please check my Code? I am getting an error "String cannot be converted to Realnumber".
15th Dec 2019, 1:22 PM
Preet
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The problem is here: public Realnumber addition(Realnumber s) { Realnumber p=new Realnumber (r+s.r); // ERROR:String cannot be converted to String return toString(p); } you need to return p. toString() returns a String
15th Dec 2019, 3:34 PM
Denise Roßberg
Denise Roßberg - avatar
0
Preet Or else try like this for your requirement, Change addition and toString function return types to double. and return double value directly from toString function.
15th Dec 2019, 4:08 PM
Jayakrishna ūüáģūüá≥