Variables assigned to objects

I need to know how to create an object of Dice with Die1 and Die2.
would I just start with
Dice Die1 = new Dice();
Dice Die2 = new Dice();

Here is where I would need to assign the value to Die1 and Die2 for the setUpperFace and Im not sure how to do that.

import java.util.*; // Imports scanner and random utilities public class Die2 { public static void main (String [] args) // begin main method { int UpperFace = setUpperFace(); System.out.println("your first die roll is " + Die1.getUpperFace + "your second die is a " + Die2.GetUpperFace); } public static int Roll() // begins method to generate a random number { Random generator = new Random(); // initiates the random generator int number = generator.nextInt(6) + 1; // generates a random number between 1 and n return number; // returns random number to the main method } // ends method generating random number public static int setUpperFace() { int UpperFace = Roll(); return UpperFace; } public static int getUpperFace() { return UpperFace; }

Your class is called Die2. There is no object defined for Dice, so your statements:

Dice Die1 = new Dice(); Dice Die2 = new Dice();
are syntactically correct but not correct for the situation you've shown us. With the object Die2, you would instead create Die2 objects, maybe Dice1 and Dice2, as in:

Die2 Dice1 = new Die2(); Die2 Dice2 = new Die2();
OR, you could rename the class you've written to "Dice." That might be simpler to implement and less confusing in the long run.

Tom Orr wrote:...
import java.util.*; // Imports scanner and random utilities public class Die2 { public static void main (String [] args) // begin main method { int UpperFace = setUpperFace(); System.out.println("your first die roll is " + Die1.getUpperFace + "your second die is a " + Die2.GetUpperFace); } public static int Roll() // begins method to generate a random number { Random generator = new Random(); // initiates the random generator int number = generator.nextInt(6) + 1; // generates a random number between 1 and n return number; // returns random number to the main method } // ends method generating random number public static int setUpperFace() { int UpperFace = Roll(); return UpperFace; } public static int getUpperFace() { return UpperFace; }

I don't think setUpperFace and getUpperFace are doing quite what you intend. I see two different variables called "UpperFace." One is local to the setUpperFace method, and is only being used as a temporary variable for the value returned by Roll(). The method is not setting any class or instance variable (which don't appear to exist). The other "UpperFace" variable is local to the main method, and doesn't appear to be used for anything. The getUpperFace method won't be able to return anything, because there doesn't appear to be an "UpperFace" variable defined within that scope.

Also, be careful with your syntax. Java is case sensitive, so "GetUpperFace" is not the same as "getUpperFace" -- both of which appear in line 7. But neither of these will work, because a method call also needs parentheses. That is, getUpperFace(). And by convention, Java variable and method names begin with lowercase characters.

Ok thanks for the help. I have made some changes and here is what I have.


import java.util.*; // Imports scanner and random utilities public class Dice { public static void main (String [] args) // begin main method { Dice Die1 = new Dice(); Dice Die2 = new Dice(); int UpperFace = setUpperFace(); System.out.println("your first die roll is " + Die1.getUpperFace() + "your second die is a " + Die2.getUpperFace()); } public static int setUpperFace() { int random = Roll(); return random; } public static int Roll() // begins method to generate a random number { Random generator = new Random(); // initiates the random generator int number = generator.nextInt(6) + 1; // generates a random number between 1 and n return number; // returns random number to the main method } // ends method generating random number public static int getUpperFace() { return UpperFace; } }

Let's take a step back. When you think about defining a class, think about what the object should HAVE (properties) and what it should DO (methods).

Your class is modeling a die. As you've already determined, an "upperFace" is a property it should HAVE (which defines its "state"), and "roll()" is something it can DO. These suggest something like this...
class Die { private int upperFace; //this instance variable is what you're missing public void roll() { //... } }
Notice that the object's state (upperFace) is private, which prevents it from being changed by some other object. But other objects might need to know the value of upperFace, and that's where the accessor (or "getter") method comes in. It simply returns that value.
class Die { private int upperFace; public void roll() { //... } public int getUpperFace() { return upperFace; //returns value of instance variable } }
A mutator (or "setter") method provides a way to set the value. Typically it would work like this...
public void setUpperFace(int value) { upperFace = value; //assigns parameter passed in to the instance variable }
But I'm not sure you want to be able to set a particular value passed in from outside, so you might not need a setter at all. Instead, upperFace should probably be determined only by calling roll(), which would just assign a new value to upperFace. In other words, roll() changes the state of the die.
public void roll() { upperFace = ... //assign new value here }
Work with these ideas a bit, and see if that helps.

I really do want to understand this stuff. Here is what I am trying now. I think I keep trying to rethink everything too much. Im not sure when I would use static and not use static. I dont understand where to put the {} brackets on a class vs a method and how a class and a method differ. Couldnt I just make a method that represents a die roll and it would work the same as a class that represented a die roll? Is the class just a seperate program that can be accessed by another program where a method could only be accessed from within a class? I am feeling so dumb and confused. This looks like it should be so simple and basic that I am just not getting some basic flow of the programming. UGH



import java.util.*; // Imports scanner and random utilities public class Die { private int UpperFace; UpperFace = roll(); } public static int roll() // begins method to generate a random number { Random generator = new Random(); // initiates the random generator int number = generator.nextInt(6) + 1; // generates a random number between 1 and n return number; // returns random number to the main method } // ends method generating random number public static void setFaceValue(UpperFace) // begins method to generate a random number { return FaceValue; // returns random number to the main method } public static int getFaceValue() // begins method to generate a random number { return FaceValue; // returns random number to the main method } }

Im not sure when I would use static and not use static.

Static (either variables or methods) members belong to the class which defines them. You don't need an instance of the class to access them. On the other hand non-static members belong to the each instance of the class.

I dont understand where to put the {} brackets on a class vs a method and how a class and a method differ

Well think of a class as a container of both properties (variables) and methods. And the brackets ({}) are used the same way for a class and a method i.e.: To wrap their contents.

Is the class just a seperate program that can be accessed by another program where a method could only be accessed from within a class?

Your program may consists of one or more classes, they actually define your program. And no, a method can be accessed from other class instances (depending on their visibility) as well as from the same class which defines it. Being static or non-static applies here as you can't access an instance (non-static) method from a static context.

I have the feeling you made everything static because you're calling things from the main clause.
Actually you want to create an object in Main and work from there.
import java.util.Random; public class Die { private int upperFace; public static void main (String [] args) { Die die1 = new Die(); // You instantiate the class, creating a Die object die1.Roll(); // You call the non-static method from the Die object. The rolled value gets stored in the die1 upperFace class member. Die die2 = new Die(); die2.Roll(); System.out.println("your first die roll is a " + die1.getUpperFace() + " and your second die is a " + die2.getUpperFace()); } public void Roll() // This is the setter because setting a value manually on a die is called cheating ;) { Random generator = new Random(); this.upperFace = generator.nextInt(6) + 1; } public int getUpperFace() // Read the value you rolled { return this.upperFace; } //....... }