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This article mainly explains "what are the advantages and disadvantages of Kotlin language". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the advantages and disadvantages of Kotlin language".

What are the advantages of the Kotlin language?

Kotlin language is praised as the Swift in the Android world.

In short, it can be summed up like this.

Fully compatible with Java

Null safe

Support for lambda expressions (better than Java8)

Support for expansion

Experience a consistent development tool chain

What does using Kotlin mean for Android developers?

For Android developers, using Kotlin has the following advantages:

Fewer null pointer exceptions

Less amount of code

Faster development speed

A more consistent development experience

What is Kotlin

The Kotlin language was developed by JetBrains, which was originally intended to generate JavaScript code quickly, but now Kotlin supports Android development and provides a series of Android development plug-ins. Due to the natural advantages of JetBrains (Android Studio is made by adding some plug-ins to IDE developed by JetBrains), Android Studio's support for the Kotlin language is also in place.

Take a look at what the Kotlin language brings to us.

Null Safe

Null pointer exceptions are indeed a problem that has plagued Java programmers for years. The Swift language cleverly solves this problem, and Kotlin uses the same solution, but the syntax is not quite the same.

Let's make a simple comparison with the Java language:

Java

Room room =...; if (null! = room & & null! = room.window) {room.window.open ();}

Kotlin

Val room: Room? =. Room?.window?.open ()

From common sense, we know that a room may or may not have windows, and if there are no windows, calling the open method will naturally result in a null pointer exception. The Java language handles null values before calling the method, while the Kotlin language uses? Operator, which means, what if? If the preceding object is empty, the null value is returned directly, and the subsequent statement is no longer executed. It has a professional name: Optinal Value (optional value)

Compared with Java language, the processing method of Kotlin language is much simpler, and more importantly, my mother no longer has to worry about null pointer exceptions in my program-_-

Careful readers should find that the Kotlin language also removes the semicolon, which is consistent with the way the Swift language handles it.

On the specific use of Optional Value, I will use a special chapter to explain to you, please look forward to my series of Kotlin language tutorials.

Function

In the Kotlin language, classes are finally no longer first-class citizens. Kotlin language began to support process-oriented programming, Kotlin language can declare global functions, inline functions, etc., but also support function nesting, using functions as method parameters and other operations. For some simple operations, creating a new class to deal with is indeed sometimes a headache, and the Kotlin language finally frees us from this awkward situation.

Let's take a look at the simple writing of function declarations and make a simple comparison with the Java language.

Java

Public Sting sayHello (String name) {return "Hello," + name;}

Kotlin

Fun String sayHello (name: String?): String {return "Hello, $name"}

The writing of the function is quite different. The Kotlin syntax is similar to that of the Swift language. Each function must be declared with the fun keyword, followed by the parameter type and the parameter name. For Java language development students can need a short adaptation process.

Similarly, I will specifically explain the Kotlin function in a later article

Lambdas

Closures should be a feature that Java programmers are looking forward to, and fortunately, Java8 has begun to support this feature. The two are very similar. Let's make a simple comparison with the closure of Java8.

Java8

Interface Sum {int add (int xpenint y);} Sum sum = (xjiny)-> x + y

Kotlin

Val sum: (Int,Int)-> Int = {xpene y-> x + y}

As you can see, the syntax of the two is very similar, and they also support type derivation and shorthand; the difference is that because the Java language is completely object-oriented, the closure must correspond to the interface one by one, while the Kotlin language naturally supports functional programming, so it can be used in the parameters without declaring the corresponding interface.

Extension

This is one of my favorite features, and the Kotlin language supports extensions to existing classes. Java programmers should be familiar with this feature, which is one of the features of the Swift language. The so-called extension is to add new methods, properties and other operations to the existing class without using inheritance, and the extension will not destroy the existing class methods, but only dynamically add them when they are used. One principle should be kept in mind: extension is better than inheritance

The Java language does not support this feature.

Kotlin

Fun MutableList.swap (index1: Int, index2: Int) {val tmp = this [index1] / / 'this' corresponds to the list this [index1] = this [index2] this [index2] = tmp}

Data Class

In the process of development, we often have to write some Model classes and constantly use development tools to generate set/get methods. Data Class is created to simplify this operation. Data classes automatically generate set/get methods instead of explicitly generating set/get methods. See the following simple usage:

Kotlin

Data class Person (var name: String?,var age: Int?)

Just use this line of code to complete the creation of the Model class, and Kotlin will automatically generate the set/get method for us, greatly simplifying the writing of the Model class. However, Java programmers do not need to envy, many Java frameworks can also achieve this, such as the Auto Value framework launched by Google, and so on.

Operator Overloading

This feature also exists in the Swift language and in the C++ language. This feature is a double-edged sword, the use of operator overloading can simplify the use, but also lose some code readability. Therefore, when using operator overloading, please consider carefully.

We won't be able to talk about the features of the Kotlin language for a while, so let's make a simple comparison with the Java language on some of the more important features:

Language feature KotlinJavaNull Safe support Java8 support global function support Lambdas support Java8 support Extension support Data Class support (dependent framework required) Operator Overloading support

Java languages are fully interoperable.

You may be worried about what to do with the previous Java code after using Kotlin. This worry is completely superfluous. JetBrains ensures that the Kotlin and Java languages can fully call each other, and Kotlin will eventually be compiled into Java bytecode.

Advantages of Kotlin language

According to netizens' statistics, using Kotlin language can reduce code writing by about 30%. At the same time, you don't have to worry about null pointer anomalies. Because of JetBrains's natural genes, Kotlin can be better maintained and upgraded. This is also a good counterattack to Oracle's frequent lawsuits against Google. After the release of the Kotlin language, many foreign developers have launched a large number of useful Kotlin frameworks, so you don't have to create wheels again. At the same time, the Kotlin language can be seamlessly connected to the Java language. What are you waiting for?

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