Slide Show with Recursion in Android

I was developing an app and the tutorial consisted of wire frame illustrations that needed to be displayed as a slideshow when the user wants to view the tutorial. Several pictures, one slideshow. Simple enough right? Apparently not …

I came across this link by fellow blogger david. It is a neat solution to the problem and definitely more fault tolerant. But writing that much code for swiping through only a few pictures quite quickly? (in my case I had 10 slides).

So I decided to use a countdown timer and some recursion. While my solution (arguably) is clumsy, I think it’s cool. So here you go.

THE .XML: Same as david’s. Using a frame layout and stacking your ImageView‘s on top of one another.
mactivity.xmland so on. The special part is in a separate class called ‘ImageSlider’ which contains a countDownTimer which progressively makes the other pictures visible.


code2Notice that I put all the ImageView’s into an array and then switch through each one during the recursion. Slide # 1 is excluded because this is the one you start on. But after that, you go from 1 to 2, 2 to 3, 3 to 4 … and so on. The recursion is on line #54. Notice the if prevents an out of bounds error.

While it may seem clumsy, I think this is a simple solution. You can literally take this function and plop it into your main activity or any activity that needs a series of pictures to fade in/out. Notice that this class is not an activity.

The countDownTimer is a very powerful class. Hope you enjoyed this little demonstration.

Please do ask me if you require further clarification.



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