Is the "quality" of Android interviews so high these days? Really the tattoo artist closed his eyes and showed me a face.....∑(っ°Д°;)っ

What is high quality?

There are back and forth, see tricks and tricks. All interviewers hope to show their abilities as much as possible within their own abilities (I’m not bad, send me an Offer soon), and I hope to chat with some of the interviewers, and the conversations are not bad. This is the same as when everyone first started looking for the other half. A common "language" and a common "topic" are the basis for further in-depth. A good interviewer is like a host, more of a guide, allowing you to show your talents .

At present, the app development of large companies must design the architecture based on the ideas of modularization, hierarchy, componentization and control, and the foundation of all this is based on the realization of the underlying principles of the Android Framework system framework. Factory interview questions.

For example: Framework that high salary must ask

• 1. What are the methods of multi-process communication in Android?
• 2. Which process communication have you used? What is the principle? (ByteDance, Xiaomi)
• 3. Describe the principle of the Binder mechanism? (Oriental Headlines)
• 4. What is the working process of the Binder thread pool? (Oriental Headlines)
• 5. How does Handler communicate with threads, and what is the principle? (Oriental Headlines)
• 6. Handler is blocking or non-blocking if there is no message processing? (ByteDance, Xiaomi)
• 7.handler.post(Runnable) How is runnable executed? (ByteDance, Xiaomi)
• 8. Both the handler's Callback and handlemessage exist, but the callback returns true, will handleMessage still be executed? (ByteDance, Xiaomi)
• 9. What is the difference between sendMessage and postDelay of Handler? (byte beating)
• 10.What is IdleHandler? How to use it and what problems can it solve?
• 11. Why does Looper.loop not block the main thread? (Tencent)
• 12. Why does the Looper infinite loop have no ANR (station B)
• 13. How is Looper created in the child thread? (ByteDance, Xiaomi)
• 14. Relationship between Looper, handler, and threads. For example, how many Loopers can one thread correspond to how many Handlers? (ByteDance, Xiaomi)
• 15. How to update the UI, why can't the child thread update the UI? (Meituan)
• 16. The principle of ThreadLocal, and how is it applied in Looper? (ByteDance, Xiaomi)
• 17. What ways does Android store data?
• 18. SharedPreference principle, what is the difference between commit and apply? What precautions should be taken when using it? (Tencent)
• 19. How to judge whether an APP is in the foreground or the background?
• 20. How to keep the application alive?
• 21. The size of a picture 100x100 in memory? (byte beating)
• 22. The principle and function of Intent, what types of parameters can be passed? I
  
  believe that many interviewers who have interviewed in large factories have encountered these questions. In addition, Framework, as the Android framework layer, provides many APIs for App to call, but many The mechanisms are all packaged by the Framework for the app to use. If you don't know the principles of these mechanisms, it is difficult to optimize on this basis.

For example : what kind of StartingWindow to customize; when can the width and height of the picture be obtained; how to do DelayLoad to be more appropriate; when the Service starts without affecting the startup speed; is it really visible when the Activity onResume callback is called? Why does Redex speed up app startup?

Another example is the Handler, MessageQueue, and Looper that we often say. Looking at the source code, you can better understand those concepts: what does ThreadLocal do; the relationship between Thread and Handler; why can't the UI be updated in the child thread?

Why do big factories have to ask Framework in interviews?

Some classmates said: I didn't say that I was proficient and good at Framework, and I couldn't escape these problems. Because the current app development of large companies should be based on the ideas of modularization, hierarchy, componentization, and control to design the architecture, and the foundation of all this is based on the realization of the underlying principles of the Android Framework system framework , so it is related to it. knowledge is very important.

And at present, the apps of the first-tier enterprises are multi-threaded and multi-process, and the Android inter-process communication mechanism is Binder, and the native inter-thread communication is Handler. Binder and Handler are a knowledge point that must be mastered to understand the Android operating mechanism. It is a must-see knowledge point for first-line enterprise interviews!

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• The first Binder series - the beginning
• Section II Binder Driver Preliminary Exploration
• Section 3 Binder Driver Revisited
• Section 4 Binder starts ServiceManager
• Section 5 Get ServiceManager
• Section 6 Registration Service (addService)
• Section 7 Get Service (getService)
• Section 8 Framework Layer Analysis
• Section 9 How to use Binder
• Section 10 How to use AIDL
• Section 11 Binder Summary
• Section 12 Full Analysis of Binder Interview Questions
• …

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finally

Being a programmer is easy, but being an excellent programmer requires continuous learning, from junior programmers to senior programmers, from junior architects to senior architects, or to management, from technical managers to technical directors. Different abilities are required. Determine your career direction early, in order to get rid of your peers in work and ability improvement.

• No matter what your current level is, you must [continue to learn] without chicken soup, others seem effortless, but in fact it takes a lot of effort, these four words are my suggestions! ! ! ! ! ! ! ! !
• I hope that every IT engineer who works hard to live will get what he wants, because we work hard and we deserve it.