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This article introduces the relevant knowledge of "what Kotlin optimization methods are available to improve development skills". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Generate a Kotlin list with one line of code

Creating a list with default values in Kotlin is very simple. This line of code creates an array of integers of length 10, with each element initialized to 1:

IntArray (10) {1} .asList ()

But what if you want to create a list with different elements? the classic way to do this is to use a for loop, of course, but it only takes one line of code to use Kotlin:

Use the "let" function to check for nullable properties

We usually use the "if not null" control structure to check the null of the type before doing any subsequent operations. Using Kotlin's let extension functions helps avoid complex branching logic. Kotlin's let is a scoped function, and properties declared inside it cannot be used externally. You can use it to nest let or to link a set of nullable objects.

Use the Elvis operator (?:) of Kotlin to provide default values for nullable attributes. For example, in the above code, you can call doSomething (a?: 0) as a function to ensure that a has a default value.

Use the "require" or "check" functions to handle early exit conditions

The require function validates the passed argument and throws an Illegal Argument Exception if it is false.

The check function throws an Illegal State Exception when the object state is false. Both methods are useful when setting an early exit condition in Android's Kotlin code library.

For simple scenarios, method references are preferred rather than Lambda expressions

Although lambda expressions are good in most use cases, it is better to use method references when you only need to access properties. The member reference is indicated by::, the class or object is written on the left, and the called property is written on the right. Consider the following example. In this context, using member references instead of lambda expressions makes the code shorter and easier to read.

Easily split lists using the "partition" and "groupBy" operators

Partition can split a list into a pair of sublists, the first sublist containing elements that meet the specified criteria, and the rest in the second sublist. GroupBy returns the mapping of the sublist in the form of key-value pairs. You can get a list of lists by calling the values property on groupBy.

The following example demonstrates the use case for each method:

Swap two attributes with one line of code

Exchanging two variables is the first programming problem that many developers face. The traditional method is to define a temporary variable to exchange properties. Of course you can replace this approach with a = a murb and b = b mura and reduce the code to two lines, but there is a better way. By using Kotlin's common expressions, you can exchange two attributes in one line:

A = b.also {b = a}

Use the "apply" and "with" functions to reduce boilerplate code

Apply and with are two important scope functions that help eliminate explicit references to objects when setting object properties. To some extent, both functions can convert the object before it is returned. The apply function is called when the object is initialized, and the with function needs to pass the object as an argument. This reduces some boilerplate code and makes the code base clear.

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