I\'m new to Android development and I just installed Android Studio version 1.2.1.1. I created a project, HelloWorld, and chose the default blank activity, Darcula theme, an
Android gives you the option to define your own style format, which the default project you made did. It created a style named 'textViewStyle'.
If you look at the text view instead of the design view (you can switch by pressing the tab at the lower left in the part where you get the error that it can't render) you will see that the textView or the app itself contains a line android:theme="@style/textViewStyle".
You can either remove this line, or track down the error in the styles.xml file in the res/values folder. This is the file that defines the style for the app.
If this doesn't help you it could be that the style is defined in your AndroidManifest.xml file, look at the tag, it will contain a line saying android:theme="@android:style/textViewStyle", change that to android:theme="@android:style/Theme.DeviceDefault" and you should be good to go.
More info on custom themes: http://developer.android.com/guide/topics/ui/themes.html
Since you are a beginner, more on general Android development: http://developer.android.com