How to run a method on the main thread from a side thread?

Question

Java

I am writing a program in which it is necessary to check for devices connected to a smartphone. If the device is connected, a picture should appear on the screen. I check with a timer. But I can't show a picture from a neighboring thread. How do I run a method on the main thread via a side thread?

Answer 1

You can pass the Handler of the main thread
In the main thread, create:

Handler handler = new Handler(Looper.getMainLooper());
// Передаем его в побочный поток

In the side we use:

handler.post(new Runnable() {
  public void run() {
    // Код для основного потока
    // ...
  }
});

Or, as advised above, it's easier, through runOnUiThread

Answer 2

runOnUiThread.

Answer 3

Observer/Observable from JDK7+. If JDK6, then implement this template yourself.