Android is a vast ecosystem of devices and before we can initialize our variables any further we need to know details about the device the game will be running on.

We will write some code to detect the resolution of the screen. The aim of the code when we are done is to store the horizontal and vertical resolutions in our previously declared variables, numberHorizontalPixels, and numberVerticalPixels. Also, once we have the resolution information we will also be able to do calculations for initializing gridHeight and blockSize.

First, let's get the screen resolution by using some classes and methods of the Android API. Add the highlighted code in the onCreate method as highlighted next.

/*
   Android runs this code just before
   the player sees the app.
   This makes it a good place to add
   the code that is needed for
   the one-time setup.
 */

@Override
protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);

   // Get the current device's screen resolution    Display display = getWindowManager().getDefaultDisplay();
   Point size = new Point();
   display.getSize(size);

   Log.d("Debugging", "In onCreate");
   newGame();
   draw()'
}

The code gets the number of pixels (wide and high) for the device in the following way. Look again at the first new line of code.

Display display = getWindowManager().getDefaultDisplay();

How exactly this works will be explained in more detail in Chapter 11, Collisions, Sound Effects and Supporting Different Android Versions when we discuss chaining. Simply explained, we create an object of type Display called display and initialized with the result of calling both getWindowManager then getDefaultDisplay methods in turn which are part of the Activity class.

Then we create a new object called size of the Point type. We send size as an argument to the display.getSize method. The Point type has an x and y variable already declared, and therefore, so does the size object, which after the third line of code now holds the width and height (in pixels) of the display.

These values, as we will see next will be used to initialize numberHorizontalPixels and numberVerticalPixels.

Also, notice that if you look back to the import statements at the top of the code the statements relating to the Point and Display classes are no longer greyed out because we are now using them.

The explanation just given is necessarily incomplete. Your understanding will improve as we proceed.

Now we have declared all the variables and have stored the screen resolution in the apparently elusive x and y variables hidden away in the size object, we can initialize some more variables and reveal exactly how we get our hands on the variables hidden in size.