When we need to click or select a control, it is checked and unchecked states in different styles, we can use the state list of relevant knowledge.
Sample code is as follows:
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="true" android:drawable="@mipmap/aaa"/>
<item android:drawable="@mipmap/bbb"/>
</selector>Other state-related as follows
| Status Type | Explanation | Commonly used controls |
| state_pressed | Whether Press | Button Button |
| state_checked | Check whether | Radio button RadioButton, CheckBox checkbox |
| state_focused | Whether gets focus | EditText text edit box |
| state_selected | Check whether | Each control can be |