Explanation of JetBoy example for dev.android.com?

I have developed many applications for desktop or web in java, but never for android.

What little I have practiced with was weird because I am used to SWING. Since it uses .xml files for applications I was wondering if you needed this also in games?

For example there is a a good example at http://developer.android.com/resources/samples/JetBoy/index.html. I was hoping someone could explain two things for me.

1. How is the image drawn to the screen?
2. How do you listen开发者_StackOverflow for user input? (Eg. Clicks, drawing, swiping, ect...)

I have made games on the desktop so you don't have to get in depth, but I found it hard to understand the code. (What I was suppose to do special for android.)

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(Another way to put it:)

I guess basically what I am asking is how to I draw an image that will in turn listen to clicks and such without adding a button? Or do I need to add an invisible button? Then if I did have to add a button how would I listen for swiping and drawing?

Also I saw some methods like doDraw(), but did not see where they were putting the image so it would appear on the android device.

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JetBoy is rather complicated for a beginner, check these simple examples which are based on the same principles as JetBoy: How can I use the animation framework inside the canvas?

Everything is done by drawing bitmaps on the view's canvas and an event which detects when and where the sreen was touched.

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I think this will tell you everything you need to know, in a comprehensive, 31 part series detailing the creation of Light Racer 3d for Android.

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If you are not going to use any Game Engine ,
basically you extend android.view.SurfaceHolder
and then overide these methods,
public boolean onTouchEvent(MotionEvent event)
protected void onDraw(Canvas canvas)

go through these articles.It teaches everything you need from the scratch