Small details to be noticed during Android Development

1. The main UI thread cannot be updated in the Child thread. It must be updated using the Handler, AsyncTask, or View postDelay () method.

2. The Toast cannot be displayed in the Child thread. (This is similar to the first point)

3. If an activity is set to the singletask mode. This will affect the sequence of startActivityForResult () calls. Therefore, onActivityResult () cannot be used normally ().

4. The scaleType attribute of ImageVIew is invalid for the src attribute and must be set to the background attribute.

5. Differences between android: layout_gravity and android: gravity

From the name, we can see that android: gravity refers to the element itself, and the text of the element itself is displayed in any place by changing the attribute settings, but not set to the left by default.

Android: layout_gravity is relative to its parent element, indicating where the element is displayed.