Basic Concepts and Usage in J2Objc Annitations Framework

J2OBJC is a tool for converting Java code into Objective-C code, enabling developers to use the Java language on the iOS platform for development.In order to better support this conversion process, J2OBJC provides a set of Annotion framework to add meta data to Java code to guide the conversion process and improve the quality of the Objective-C code generated. The basic concepts and usage in the J2Objc Annotions framework are as follows: 1. @mapping: @mapping Note is used to specify the Objective-C mapping of the method and attributes in the Java code.This is very useful for the methods or attributes that have special naming requirements in Objective-C.By providing a mapping relationship, developers can clearly tell how J2OBJC should generate corresponding code in Objective-C.The following is an example: @Mapping("UIViewController(customeCategory)") public class CustomViewController extends UIViewController { @Mapping("initWithNibName:bundle:") public CustomViewController(String nibName, NSBundle bundle) { super(nibName, bundle); } } In the above code,@MAPPING ("UIViewController (CUSTOMECATEGORY)") indicates that J2OBJC maps the Java class CustomViewController to Objective-C UIViewController and classifies it as "CustomCat Egory "category. 2. @block: @block annotation is used to mark the Java method as an Objective-C barrier interface.This is very useful for processing the callback function and commission mode.By using @block annotations, developers can specify the parameters and return types of the method, and indicate the type type used in the Java code.The following is an example: public class MyViewController extends UIViewController { @Block("void(^)(BOOL)") public void completionHandler(boolean success) { // Implementation } } In the above code,@Block ("Void (^) (BOOL)") indicates that J2Objc converts the parameters and return types of the CompletionHandler method to Objective-C block type (VOID (^) (BOOL)). 3. @Notimplemended: @NotimpleMenTED annotation is used to mark the unrealized method in the Java code.This is very useful for temporarily left empty implementation or providing instructions for future implementation.When using @NotimpleMented annotations, J2OBJC will generate unrealized place occupies in the conversion Objective-C code.The following is an example: public class MyViewController extends UIViewController { @NotImplemented public void placeholderMethod() { // Will not be implemented yet } } In the above code, when converting to Objective-C code, a unrealized place occupies in the corresponding method PlaceholderMethod. To sum up, the J2Objc Annotations framework allows developers to use annotations in the Java code to specify certain metadata to improve the code generation during the conversion process.@Mapping annotations are used to specify the Objective-C mapping relationship of Java code elements,@Block annotations are used to mark block callback interfaces, and@notimplemented annotations are used to mark the unrealized methods.By using these annotations, developers can more flexibly control the quality and structure of the generated Objective-C code. I hope the introduction of the basic concept and usage of the J2Objc Annotations framework is helpful to you!