In android:android4.2, there are 4 new parameters in the Relativelayout view, like Layout_alignstart

        Why is this layout_alignstart better than Layout_alignright and layout_toleftof?

The new parameters are designed to fit some areas of right-to-left reading habits. For example, when you want to fit in Arabic, start represents the right, and Chinese is left.
Other words
When I use start to set the time, if the display of Chinese, this start represents the left side; If Arabic is displayed, this start represents the right

In android:android4.2, there are 4 new parameters in the Relativelayout view, like Layout_alignstart