Android engineers, how to use kotlin to provide productivity?

Kotlin Known for its simplicity , And in our practice , Being more concise means being more efficient . in fact , In the use of Kotlin Major of Android Among developers , There are as many as 67% Person representation Kotlin Has helped them improve their productivity . In the following content , I will share some Kotlin Ways to help our partner engineers improve productivity , And I'd like to introduce you to Kotlin function .

In the use of Kotlin Major of Android Among developers , There are as many as 67% Person representation Kotlin Has helped them improve their productivity

concise 、 Simple and efficient

Kotlin Simplicity has an impact on every stage of development :

• As a code writer : You can focus on the problems that need to be solved ( Not grammar ). Less code means less testing 、 Less debugging and less writing Bug The opportunity of .
• As a reviewer and maintainer : There's less code you need to read , So it's easier to understand what code does , So it's easier to review and maintain the code .

The following example comes from Flipkart The team :

“ In an internal investigation ,50% The developers mentioned , For the use of Kotlin Write modules , It is estimated that the time required to complete the function will be reduced .”

——Flipkart

Kotlin The function and productivity of

because Kotlin Simplicity and high readability of , majority Kotlin All of these functions can improve productivity . Let's look at some of the most common features .

Default parameters and builders

stay Java In programming language , When some of the parameters in your constructor are optional , You usually use one of two methods :

• Add multiple constructors ;
• Realization Builder mode .

In the use of Kotlin when , Due to the existence of default parameter function , You don't need to use both methods . Default parameters allow you to overload functions without additional template code .

Yes Kotlin The use of Cash App Teams can clean up a lot of builders , This reduces the amount of code they need to write . In some cases , The amount of code is reduced 25% As much as .

for instance , The following code is a Task Objects are implemented using the builder and default parameters, respectively . The Task The only required parameter is the task name (name):

/* Copyright 2020 Google LLC.    
   SPDX-License-Identifier: Apache-2.0 */
3
- public class Task {
-     private final String name;
-     private final Date deadline;
-     private final TaskPriority priority;
-     private final boolean completed;
-
-     private Task(String name, Date deadline, TaskPriority priority, boolean completed) {
-         this.name = name;
-         this.deadline = deadline;
-         this.priority = priority;
-         this.completed = completed;
-     }
-
-     public static class Builder {
-         private final String name;
-         private Date deadline;
-         private TaskPriority priority;
-         private boolean completed;
-
-         public Builder(String name) {
-             this.name = name;
-         }
-
-         public Builder setDeadline(Date deadline) {
-             this.deadline = deadline;
-         return this;
-         }
-
-         public Builder setPriority(TaskPriority priority) {
-             this.priority = priority;
-             return this;
-         }
-
-         public Builder setCompleted(boolean completed) {
-             this.completed = completed;
-             return this;
-         }
-
-         public Task build() {
-             return new Task(name, deadline, priority, completed);
-         }
-     }
-}
+ data class Task(
+     val name: String,
+     val deadline: Date = DEFAULT_DEADLINE,
+     val priority: TaskPriority = TaskPriority.LOW,
+     val completed: Boolean = false
+)

You can go through our article Kotlin Vocabulary | Kotlin Default parameters Learn more about default parameters .

object Keywords and singletons

The singleton pattern It's probably one of the most common design patterns used by software developers , It can help us create a single instance of an object , Other objects can access and share the instance .

When creating a singleton , You need to control how objects are created , Ensure that there is only one instance and that the code is thread safe . And in the Kotlin in , You only need to use one keyword : object.

/* Copyright 2020 Google LLC.  
   SPDX-License-Identifier: Apache-2.0 */

- public class Singleton{
-    private static volatile Singleton INSTANCE;
-    private Singleton(){}
-    public static Singleton getInstance(){
-        if (INSTANCE == null) {                // Single Checked
-            synchronized (Singleton.class) {
-                if (INSTANCE == null) {        // Double checked
-                    INSTANCE = new Singleton();
-                }
-            }
-        }
-        return INSTANCE;
-    }
-    private int count = 0;
-    public int count(){ return count++; }
- }

+ object Singleton {
+     private var count = 0
+     fun count(): Int {
+         return count++
+     }
+ }

The operator 、 String templates and more

Kotlin The simplicity and simplicity of language , It's also reflected in operators overloading 、 deconstruction And string template and other functions . These features make the code very readable .

for instance , Suppose we have a library and some books . So the operation of removing books from the library and processing and printing book titles , It can be written as follows :

/* Copyright 2020 Google LLC.  
   SPDX-License-Identifier: Apache-2.0 */

fun borrow(){
    library -= book
    val (title, author) = book
    println("Borrowed $title")
}

What we use here Kotlin Functions include :

• -= The implementation uses operators overloading ;
• val (title, author) = book Used deconstruction ;
• println ("Borrowed $title") Using a string template .

summary

Kotlin Make it easy to read and write code , It's built in with things like Single case and entrust The realization of this kind of pattern , This can help us remove those that might lead to bug Or code that increases maintenance costs . And like String template 、lambda expression 、 spread function 、 operators overloading This kind of function can make the code more concise and clear . Less code means less code to read , It also means less code to maintain 、 And fewer mistakes , To bring higher productivity .

You can read Use Kotlin Create better App To learn more about , You can also learn how developers learn from Kotlin Benefit from . If you want to use Kotlin ( One of the most popular languages in the world ) The first step , Please refer to our Getting started page .