Android应用需要大量时间才能启动

Question

I've an Android app. In the onCreate() method of splash screen I've add

    final Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            Log.i(SplashActivity.APP_NAME, "Executing post-delayed code");
        }
    , 100);

So, what I expect is that this code will get executed after 100ms after onCreate is exited.

But I can see that my app is taking 3 seconds after onCreate() to execute the post-delayed code (also UI appears after 3seconds):

08-30 19:00:45.614 4559-4559/com.example.my I/My Example: OnCreate is exited
08-30 19:00:45.621 4559-4683/com.example.my D/OpenGLRenderer:   Use EGL_SWAP_BEHAVIOR_PRESERVED: true
08-30 19:00:45.654 4559-4683/com.example.my I/Adreno: QUALCOMM build                   : 166ada0, Ifd751822f5
                                                            Build Date                       : 01/26/16
                                                            OpenGL ES Shader Compiler Version: XE031.06.00.05
                                                            Local Branch                     : AU12_SBA
                                                            Remote Branch                    : 
                                                            Remote Branch                    : 
                                                            Reconstruct Branch               : 

**08-30 19:00:45.662** 4559-4683/com.example.my I/OpenGLRenderer: Initialized     EGL, version 1.4

**08-30 19:00:48.646** 4559-4559/com.example.my I/My Example: Executing post-delayed code

Can someone please tell me why an app can take 3 seconds after onCreate() to execute post-delayed code and UI to start appearing?

Please suggest me tips on how I can optimize this time?

One more question , does handler.postDelayed() execute after onStart() / UI is shown?

Answer 1

Consider to add little larger timeout because even default android studio template set timeout time to 300 ms. You can see the comment in android fullscreen application template

/**
 * Some older devices needs a small delay between UI widget updates
 * and a change of the status and navigation bar.
 */
private static final int UI_ANIMATION_DELAY = 300;

Also much depends on your layout because Android draws it in main thread and if your UI have much nesting levels or hard drawing code it can also reduce performance.