Common problems and solutions in the J2Objc Annotions framework

Common problems and solutions in the J2Objc Annotations framework J2OBJC is a tool to convert Java code into Objective-C code.It provides a set of annotation framework to help developers' bids in Java code that requires elements that need to be retained in the Objective-C code, and mapping rules during code conversion.However, some common problems may be encountered when using the J2Objc Annotations framework.This article will introduce these problems and provide corresponding solutions. 1. Lack of J2Objc Annotations library dependencies Before using the J2Objc Annitations framework, you need to add dependence on the J2Objc Annotations library to the project construction tool.For example, in the Gradle project, you can add the following dependencies to the Build.gradle file: dependencies { Implementation 'com.google:j2objc-annotations:X.x.x' // } 2. Can't convert Java code to Objective-C code If an error occurs during the conversion of J2OBJC, it may be because some elements that cannot be converted into Objective-C are used in the code.For example, J2OBJC does not support the characteristics of Java's reflection mechanism, thread synchronization and dynamic class loading.When writing code, you need to avoid using these unsupported features. 3. Can't find the corresponding mapping rules in the Objective-C code J2Objc Annotions framework uses annotations to mark specific information that should be retained during code conversion.If the corresponding mapping rules cannot be found in the Objective-C code, it may be because the relevant annotations are not used correctly.To solve this problem, you need to check the code carefully and ensure that all elements that need to be retained have been marked with appropriate annotations. Here are several commonly used J2Objc Annotations annotations and its usage: -@Translation: The class, methods, or fields that need to be retained in the Objective-C code for labeling.For example: @Translation ("MyClass") // Objective-C's class name "MyClass" is "MyClass" public class MyClass { @Translation ("MyMethod") // Objective-C's method is called "MyMethod" public void myMethod() { // code logic } @Translation ("MyField") // Objective-C's field is called "MyField" public String myField = "Hello"; } -@Mapping: Used to specify the name mapping between Java code and Objective-C code.For example: public class MyClass { @Mapping ("MyMethod") // Objective-C's method is called "MyMethod" public void myMethod() { // code logic } } -@Mappingwithuniquekeys: Similar to @mappping, but you can use multiple unique keys to identify mapping.For example: public class MyClass { @MappingwithuniqueKeys ({"mymethod", "mymethod2"}) // You can use two different methods to identify public void myMethod() { // code logic } @MappingWithUniqueKeys({"myMethod", "myMethod2"}) public void myMethod2() { // code logic } } 4. The conversion Objective-C code is low performance Due to the differences between Java and Objective-C, there is a difference in grammar and runtime, and the conversion Objective-C code may cause performance reduction.To improve performance, it is recommended to optimize the conversion Objective-C code.For example, Objective-C's native data structure and API can be used to avoid frequent Objective-C methods. In summary, some common problems may be encountered when using the J2OBJC Annotations framework, but by correcting the use of J2Objc Annotations and performing necessary optimizations, these problems can be solved, and the Java code is successfully converted into Objective-C code. Note: The above Java code example is just to explain the problem, and it is not guaranteed to run directly in the J2Objc Annotations framework.In actual use, please adjust according to the specific requirements and grammar of the J2Objc Annotations framework.