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Preface

Mobile R&D is hot, and more and more people are starting to learn android development. However, many people feel that it is easy to get started and it is difficult to grow. They are rather confused about the future. They don't know how to improve their skills and what needs to be added to the next stage. The market is also mostly talking about knowledge graphs, lacking a system and a sense of growth rhythm. I hereby compile an advanced road to android R&D, I hope it can be helpful to everyone.

Here I divide the siege lion into four stages: elementary, intermediate, advanced, and senior, and make requirements for R&D and design capabilities, tool use, system principles, and architecture.

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The JVM language has to put its own position in consideration, considering both its own ability and the historical process.

Java is a pro-son and the "indigenous people" of JVM, dominating the development direction of JVM, the tree has deep roots and luxuriant branches, "this sincerity cannot compete with each other".

Compared with other JVM languages, Kotlin is able to put itself in a more upright position. It does not have the ambition of "the princes will have a kindness" and replace it with Java. Instead, it always insists on the strong compatibility with Java. Use the Java API extensively, wrap the bloated Java code into short sentences, silently doing the work of the "paper maker". So far, Kotlin is quite capable of this role, type inference, expansion, null safety, higher-order functions , which is not practical and powerful syntax enhancement?

In my opinion, the biggest change in Kotlin for Java developers is not to reduce the time wasted on writing code, but a series of changes in thinking:

• Rather than let the developer manually control the loop, it is better to encapsulate the loop inside the class library . The three-stage for loop and while loop of the C-like language are simply the culprits of bugs and complex code;
• Object-oriented, but can't be tied up by classes and objects, liberating functions!
• Every line of code must be used on the cutting edge, to minimize template code and redundant declarations;
• The programming language should design the "default configuration" and guide developers to use the "default configuration" , such as the default class is not inheritable, the access control symbol defaults to public, the collection defaults to read-only, the type defaults to not null, etc.;
• ** Immutable objects are better than mutable objects, ** use more val and less var, more read-only collections less mutable collections, more non-null types and less nullable types;
• **Classes should "return to their heart" and only undertake the functions of "abstract objects". **Kotlin encourages the use of extensions, less stuffing APIs and implementations in classes, and try to use "class basic framework + external extension function" Pattern.

These things are implicitly communicated to developers in the process of learning Kotlin and writing Kotlin, and can guide traditional and conservative Java developers to embrace modern programming languages.

Kotlin is not a science, but a set of tools . Unlike Scala, it is not as heavy as a book, and all features are born for practicality and simplicity;

Kotlin is not a revolutionist, but a reformer . It is not Go. It has no ambition to take the world and replace it. It only has a solid goal of "making Java easier to use".

Kotlin is not perfect, but it is constantly improving . Unlike Java, which is controlled by the Oracle family, it does not allow any uncontrolled features to appear. The birth and development of Kotlin cannot be separated from the promotion of the community. More and more new features are being developed. Urged to join;

Kotlin will not cover everything, but will make up for the shortcomings of Java . Kotlin will not become C++.

Due to space reasons, this interview book has been sorted into a PDF document. If you need a complete set of the Android interview book, please like it + click on GitHub to get the information for free!

This article is included in the open source project: GitHub , which contains self-learning programming routes in different directions, interview questions/faces, and a series of technical articles, etc. The resources are continuously being updated...

Including self-learning programming routes in different directions, a collection of interview questions/faces, and a series of technical articles, etc. The resources are continuously being updated...