导读：1. UI layout is in xml, default file name is main.xml under project folder#39;s res/layout2. It was called by the class extends Activity, method name is onCreate and t......
1. UI layout is in xml, default file name is main.xml under project folder's res/layout
2. It was called by the class extends Activity, method name is onCreate and the default parameter of setContentView is R.layout.main
3. R is generated by development envrionment automatically
source: http://developer.android.com/guide/topics/ui/declaring-layout.html
Note:
1. after paste source code to editor, Source->Format, or just Ctrl+Shift+F
