Android Handler Looper thread

Calls in the thread containing the creation of the handler method, will be an error, prompt:

"Need call Looper.prepare ()"--before creating, invoke the Looper.prepare () method to create a Looper

However, the method that contains the create handler may be called in the main thread or in a child thread.

When called in the main thread, you add the Looper.prepare () method to it, it may error, prompt:

"Only one Looper can be created per thread"--within each thread, there is only a single Looper

The solution:

        if (looper.mylooper () = = null) {Looper.prepare ();}

Where the return value of the Looper.mylooper () method is the Looper object of the current thread, and the return is NULL, the Looper.prepare () method is required to create the Looper

Android Handler Looper thread