I listed seven common tasks that Android developers often face, it’s the kind of stuff that interrupts your train of tought and makes you think “Oh God.. this is boring and I have other things to do, let’s google for some code”.
And here it is. In no particular order.
Just copy and paste, no questions asked.
How to rotate a Bitmap in Android
This will rotate any
Bitmap to the desired angle, in degrees.
How to copy a file in Android
The smart way, without that nasty
new buffer thing.
How to delete a directory in Android
Yes, the directory itself and all the files and subdirectories recursively.
How to convert a byte array into an hexadecimal String
I will probably google this in the future and find my own post.
How to convert Android dps to pixels
You are welcome.
How to copy a directory in Android
Again yes, the directory itself and all the files and subdirectories recursively.
How to extract a zip archive in Android
This will extract any zip archive to the desired location on the filesystem.
Recently I had to implement some custom UI controls for one of our customers, and some of these controls involved drawing
Bitmaps with rounded corners.
Android provides a handy approach to this problem, all the magic can be done with a little help from a class named
BitmapShader you can draw bitmaps in any shape and even more, here’s an example:
BitmapShaderdoes is basically providing a pixel source to a
Paint object, when you draw something on a
Canvasyou have to specify the
Paintinstance that will be used to paint your stuff, if that
Paintis bound to a
BitmapShader you’ll get your stuff painted using the
Bitmap that the
BitmapShaderwas created with.
Here’s how to create a
BitmapShaderin place you can now draw anything you want using a
Paint which is bound to the shader, the binding can be achieved with the
setShader() method of the
Now everything is in place and you can start drawing your bitmaps, following is a list of what I did in the example screenshot above and the code I used to achieve each sample, also note that in order to draw on a
Canvas I created a custom
View subclass and I added the drawing code inside the
onDraw() method, in a real scenario however try to avoid allocating stuff inside the
Bottom corners rounded
Top corners rounded
Here’s one piece of code that comes very handy in some situations, just copy and paste this to get the SHA1 hash sum from a text String. The Hash is returned as an hex encoded human readable String, see below for an example of use:
Here’s how to use this:
The code above will print this output:
String: Hello World
SHA1 HASH: 0a4d55a8d778e5022fab701977c5d840bbc486d0
Here’s a simple code snippet that enables you to run a Runnable object on the main thread, or UI thread. This is very handy if you have to update your UI from a background thread or an AsyncTask. It does not require something in particular, this code can be run from everywhere inside your application: