how is the Apple.addprice working tried to switch with subtract doesn't work

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I understand that your creating a Apple class apple and passing variable applePrice to it but i want to know how the addprice works how does the operator work tried to exchange subtract but didnt work like Apple.subtractPrice(100);

package en.codegym.task.jdk13.task04.task0402; /* Price of apples */ public class Solution { public static void main(String[] args) { Apple apple = new Apple(); Apple.Price(50); Apple apple2 = new Apple(); Apple.addPrice(100); System.out.println("Apple price " + Apple.applePrice); } public static class Apple { public static int applePrice = 0; public static void addPrice(int applesPrice) { Apple.applePrice = Apple.applePrice + applesPrice; } } }

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Thomas

Level 41 , Bayreuth, Germany

24 April, 11:37

Apple.subtractPrice(100); does not work because the Apple class does not have a method subtractPrice(). If you try to access members of a class (instance, static variables or instance, static methods), then these memebers must exist. That's the same for line 10 in your code. There is no Price() method in the Apple class and if you try to compile your code the compiler will throw an error. new Apple() does not create a class. It creates an instance, an object, using the Apple class' code as a blueprint. The class is already written (lines 16 - 22) and does not need to be created.

Apple apple = new Apple();

So this will create an object which is named apple. With this name apple you can access instance methods (not static methods) of a class. That's what you need to change, too (remove static in line 19) An object has it's own set of state (instance variables). Here this feature is not used. Here the method should take a parameter and add this to a static variable applePrice. Now you can invoke the addPrice(double) method on the apple object and pass it a value (this value (applesPrice) is known only by that Apple apple and not apple2 or apple3). Inside the addPrice method you add that value known only by apple to a static varible applePrice. And that static variable is accessible by all Apple objects. I may be wrong but it may be that the names of the addPrice parameter should be the same as the static variable (applePrice). If that is the case then you write Apple.applePrice if you want to access the static (class) variable (you prefix it with the class name). Otherwise that won't make any sense. If there is no name conflict and you have unique identifiers applying Apple as perefix is redundant.