Java.lang.RuntimeException:Can ' t create handler inside thread that have not called looper.prepare ()

1. When the program occurs, a run-time exception appears as shown in.

2. abnormal cause analysis. In the onchange method of Contentobserver, the Toast.maketext method is called. The OnChange method should run on a child thread, and the UI component cannot be directly controlled in the child thread of Android, otherwise it will be reported as an exception

The 3.Looper category is used to turn on a message loop for a thread. By default, the newly born thread in Android does not have a message loop turned on. (except for the main thread, the main thread system will automatically create a Looper object for it, turn on the message loop)

Java.lang.RuntimeException:Can ' t create handler inside thread that have not called looper.prepare ()