nullable 是个好东西，但可惜 Java 没有呀～

'AttachCurrentThread' in '_JavaVM'; did you mean 'attachCurrentThread'?
auto result = JVM.load()->AttachCurrentThread(&env, nullptr);
^~~~~~~~~~~~~~~~~~~
attachCurrentThread
/opt/android-sdk/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/include/jni.h:1058:10: note: 'attachCurrentThread' declared here
jint attachCurrentThread(JNIEnv** p_env, void* thr_args)

JNI 是个好东西，但是用起来千万要小心。

0x00 Background

It is common for a list to have a specific order, assuming you have a bunch of contacts in your list, you might want to sort them in alphabet order, or if you have some kind of notes, you like to sort them in time order. These sorting requirements are common and easy, you can just use a list and a comparator, just use the compare() method, however some are much complicated, like different kind of data, different sort rules, how to deal with the duplicated names. Also, you need to handle all the changes like insert, remove and updates. Sometimes it can be annoying, no worry, we have SortedList.

This is mainly for Phone UI and Tablet UI. Since Android has supported split screen since Android OS 7.0. It's not suitable to use isTablet to check whether App runs on a tablet. It might be a tablet but shows a phone UI.

2018 年 Google IO 大会给我们带来了最新的 Android Things 1.0 版本，也为与会者提供了一份完整的 Android Things develop kit。刚好有一个好朋友也去参加了这一次的 IO（羡慕ing），拿到了一套，并且慷慨的送给了我，在此先谢谢方大神！

With the power of Markdown.

0x00 Requirements background

When an application released and get used by customers, crashes and ANRs are usually the most annoying issues for developers, it's hard to get the specific context of the entire usage.

0x00 Background

When we developing and releasing an Android Application, we might encounter issues like Frozen Frames(FF) or Janks(according to Android Developer), to detect Janks during developing or logging, we can add a simple detector to check whether an application is going through a Jank.