Why learn kotlin

Now that the proportion of kotlin used in android development is getting higher and higher, coupled with the grievances between google and oracle, it is foreseeable that kotlin will become the mainstream language for android development in the future.

At the same time, as an excellent high-level language, kotlin has many features that are in common with other languages, including groovy, swift, dart, etc. After learning kotlin, you will have a feeling of knowing a little bit before learning other languages.

development toolsidea

why idea instead of android studio

idea can choose to create a java project, which can test kotlin code features very quickly, and the time-consuming of a single compilation is almost negligible.

If you test kotlin in the android project, it is no problem, but it takes a long time to wait for the project to compile each time.

View kotlin's bytecode

Idea has a built-in plugin to view the bytecode compiled by kotlin, double-click shift and enter kotlin bytecode

Since bytecode is generally difficult to grasp quickly, we can choose to decompile to generate java code to help understand some implementations of kotlin features.

THIS IS IMPORTANT!!! THIS IS IMPORTANT!!!

Version selection

Choose idea community edition for free,

download link

If it is a mac, pay attention to select the corresponding chip type

project

file - new - create a new java project
kotlin/jvm

script selection

Create a new kotlin file, mainly do not select class
Feel free to run and test kotlin features

fun main(){
    println("hello world")
}
复制代码

Script debugging

In the process of testing kotlin features, we will create multiple kotlin files. If we need to run different kotlin files, we need to do two things

Declare the main method in the file, that is fun main(){}, it is actually converted into a java entry function class, so that the compiler can recognize that it is a kotlin file that can be executed separately
Select edit configuration in the run configuration, and enter the name of your newly created file in the pop-up configuration window. For example, if the file name is test.kt, enter uppercase TestKt to debug the code in the test.kt script.

A ceremonial HelloWorld