How to create an Android file list with working back-button?

I've used this file list for my new Android app: http://android-er.blogspot.com/2010/01/implement-simple-file-explorer-in.html

But the problem is that after I've browsed through the folders and then pressing the back-button of my phone, the app is closing instead of going to the previous folder.

(becau开发者_如何学JAVAse it's still on the same activity, only some variables are changed)

Is there a possibility to fix this file browser that I can use the back-button without creating multiple activities?

Thank you!

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You can override onBackPressed in your activity and do whatever you need there to go to a previous directory.