Posts Tagged ‘Java’

These posts contain code written in Java or are somehow related to Java.

Android OpenGL: Texture from Canvas

Click here to read Android OpenGL: Texture from Canvas

Another post about Android programming, although this time, it’s going to incorporate some OpenGL techniques. The code below shows how to draw a Canvas into a Bitmap, and then, load it as a OpenGL texture object. This means that it is possible to use all Canvas methods to draw into a texture, like drawCircle(), drawPoints() or drawText(). This is useful to render text to a texture and to dynamically generate textures.

So here’s the code: (more…)

How to get Android local files URI

Click here to read How to get Android local files URI

When programming applications for Android that requires the playback of audio or video files, sometimes, there’s the need to obtain the URI of those media files instead of using a String for the absolute path. But what is a URI? A URI (Uniform Resource Identifier) is an address to an local or internet resource. It’s more like a standardized path syntax that allows pointing to a specific resource that’s available over the internet, however we are going to use it to point it to a local resource.

A URI is specially useful, when using the VideoView class to load a video located on the res folder or in the SD card. Passing the video file to the VideoView as a String won’t even work on an emulated Android device. This way, we need to get the URI of the file.


Extra life after a certain amount of points

Click here to read Extra life after a certain amount of points

Finally, a post directly related to game programming! I will explain how to write a piece of code responsible for giving an extra life to the player’s character after a certain amount of points. The  following code was written in Java, because it’s it would be shorter and easier to explain. Since this a generic algorithm, let’s assume that the game logic runs inside a method called Update() that is a member of the GameLogic class, responsible for our hypothetical game logic. Additionally, we need to have in mind that this method is being constantly called inside the game loop.

So here’s the code: (more…)

Access Activity class from View

Click here to read Access Activity class from View

So, it begins! This is the first on this blog!

Let’s start with a Android Programming tip: how to access the Activity from an instantiated View object.

The first thing to do is consider if you really need to call an Activity from a View. Take some time to analyze your classes and their relationships. Probably, the variable/method you need to access doesn’t have to be a member of the Activity class. In that case, think about placing that variable/method inside the View or create a new class that has variables/methods which can be accessed by both Activity and View. Unless an Activity variable or method (e.g. Activity.finish() ) needs to be called from the View, there is no need to try to access the Activity from the current View.

But if you need to access a method/variable of the calling Activity from the View, here is how it’s done: