[ANDROID] Searching a file and get the path to my GUI.TextField?

Friends, good afternoon!
I need your help. I am creating a way to get the path of a file when you click a button. I know Java to use the default option for the device, BUT AS I DO IN The Unity 3D?

How do I do a search for a file, and when the SELECT, grab the string of his way and in a TextField?

Come together to advance!

You have expierence with Java?

Why you dont build a Java Android plugin in Eclipse?