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Title: detailed explanation of the technical principles of Android support library solution
Introduction:
Android Support Library is a library developed by Google to support various Android devices.Among them, Annotations annotations are an important part of it. It provides a mechanism for bidding and annotations in the code to help developers write more robust and efficient code.This article will introduce the technical principles of Android Support Library Annotations.
Introduction to Annotations
Annotations annotation is a special mark that adding annotations to the Java code can provide additional information for compilers and tools.In the development of Android, Annotation's annotation provides more metadata information to help developers write better code.
2. The role of Android support library annotations
Android Support Library Annotions mainly has the following functions:
1. Auxiliary compiler conduct code check: By adding various annotations to the code, you can assist the compiler for code check, including type inspection, warning check, etc., thereby improving the quality and stability of the code.
2. Automatically generate code: Android Support Library Annitations can automatically generate some model code for developers, such as Getter and Setter methods, rewrite parent methods, etc., thereby reducing repeated labor.
3. Auxiliary IDE for code prompts and automatic completion: By using Annotations annotations, IDE can better understand the meaning and structure of the code, thereby providing more accurate code prompts and automatic completion functions to improve development efficiency.
Third, the commonly used Android support library annotations
Android Support Library Annotations provides many useful annotations. Here are several commonly used annotations:
1. @nulLABLE and @nonnull: Whether the parameters or return values used for marking methods can be empty.These annotations can help developers avoid air pointer abnormalities.
2. @Keep: It is used to mark a part of the code, indicating that the code remains unchanged during the confusion process to avoid being deleted by mistake.
3. @intdef and @StringDef: Used to limit the value range of the parameters and improve the robustness of the code.
4. @Uithread and @WorkerThread: Used for marking methods should run in UI threads or work threads to help developers avoid problems in using threads.
Fourth, example
The following is a sample code using Android Support Library Annotations:
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
public class Person {
private String name;
public Person(@NonNull String name) {
this.name = name;
}
public void setName(@Nullable String name) {
this.name = name;
}
@Nullable
public String getName() {
return name;
}
}
In the above code, the@Nonnull annotation indicates that the name parameter cannot be empty. It is used in the constructor and the setter method to avoid the problem of abnormal empty pointer.@NulLABLE annotation indicates that the return value of the getName method can be empty.
Summarize:
Android Support Library Annotations is a very practical tool in Android development that can improve the readability, stability and development efficiency of code.By using these annotations in the code, developers can better use the functions of compilers and IDEs, reduce errors and repeat labor, and generate high -quality code.
