completed homework jv-DI #1000
completed homework jv-DI #1000
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Great job on following the checklist and ensuring that all files meet the requirements! Your attention to detail is commendable, and the code looks clean and well-structured. Keep up the good work, and remember that small optimizations and informative exception messages can further enhance your code in the future. 👍 Keep coding and stay awesome! 🌟
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| import java.lang.annotation.Retention; | ||
| import java.lang.annotation.RetentionPolicy; | ||
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| @Retention(RetentionPolicy.RUNTIME) | ||
| public @interface Inject { |
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The @Inject annotation is correctly defined with the @Retention policy set to RUNTIME. This is necessary for runtime reflection. No changes needed.
| } catch (Exception e) { | ||
| throw new RuntimeException("Error initializing injector", e); |
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It is better to replace many exceptions that have a common parent with a general parental exception. In this case, you can catch ReflectiveOperationException instead of Exception to be more specific about what you are catching.
| } catch (NoSuchMethodException e) { | ||
| throw new RuntimeException("Could not find constructor for " | ||
| + clazz.getName(), e); |
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When throwing an exception, add an informative message to it. Also, don't forget to add an exception you're catching in the catch block to the RuntimeException object you throw. This is implemented correctly here, but ensure to follow this pattern consistently.
| } catch (InstantiationException | ||
| | IllegalAccessException | ||
| | InvocationTargetException e) { | ||
| throw new RuntimeException("Could not instantiate " | ||
| + clazz.getName(), e); |
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Similar to the previous comment, it is better to replace many exceptions that have a common parent with a general parental exception. In this case, ReflectiveOperationException can be used instead of listing all individual exceptions.
| if (dependency == null) { | ||
| throw new RuntimeException("No component found for: " | ||
| + fieldType); |
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When throwing an exception, add an informative message to it. The message should include details about why the injection failed, such as missing @Component annotation on the class. This helps in debugging the issue.
| throw new RuntimeException("Not allowed to inject " | ||
| + fieldType); |
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When throwing an exception, add an informative message to it. The message should include details about why the injection failed, such as missing @Component annotation on the class. This helps in debugging the issue.
| private void registerComponents() { | ||
| Class<?>[] classes = { | ||
| ProductServiceImpl.class, | ||
| ProductParserImpl.class, | ||
| FileReaderServiceImpl.class | ||
| }; | ||
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| for (Class<?> clazz : classes) { | ||
| if (clazz.isAnnotationPresent(Component.class)) { | ||
| Constructor<?> constructor; | ||
| try { | ||
| constructor = clazz.getDeclaredConstructor(); | ||
| } catch (NoSuchMethodException e) { | ||
| throw new RuntimeException("Could not find constructor for " | ||
| + clazz.getName(), e); | ||
| } | ||
| Object instance = null; | ||
| try { | ||
| instance = constructor.newInstance(); | ||
| } catch (InstantiationException | ||
| | IllegalAccessException | ||
| | InvocationTargetException e) { | ||
| throw new RuntimeException("Could not instantiate " | ||
| + clazz.getName(), e); | ||
| } | ||
| components.put(clazz, instance); | ||
| for (Class<?> element : clazz.getInterfaces()) { | ||
| components.put(element, instance); | ||
| } | ||
| } | ||
| } |
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Make Interface Implementations map a class field. You can fill it in using Map.of(). This will make the code cleaner and more maintainable.
| public class Injector { | ||
| private static final Injector injector = new Injector(); | ||
| private final Map<Class<?>, Object> components = new HashMap<>(); |
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Let's check instances map before new instance creation. This ensures that you do not create a new instance if one already exists, which would be more efficient.
| import java.lang.annotation.Retention; | ||
| import java.lang.annotation.RetentionPolicy; | ||
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||
| @Retention(RetentionPolicy.RUNTIME) |
| import java.lang.annotation.Retention; | ||
| import java.lang.annotation.RetentionPolicy; | ||
|
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||
| @Retention(RetentionPolicy.RUNTIME) |
| public class Injector { | ||
| private static final Injector injector = new Injector(); | ||
| private final Map<Class<?>, Object> components = new HashMap<>(); |
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| private final Map<Class<?>, Object> components = new HashMap<>(); | |
| private final Map<Class<?>, Object> components = new HashMap<>(); | |
| private static final Map<Class<?>, Class<?>> interfaceImplementations; | |
| static { | |
| interfaceImplementations = Map.of( | |
| FileReaderService.class, FileReaderServiceImpl.class, | |
| ProductService.class, ProductServiceImpl.class, | |
| ProductParser.class, ProductParserImpl.class); | |
| } |
| Class<?>[] classes = { | ||
| ProductServiceImpl.class, | ||
| ProductParserImpl.class, | ||
| FileReaderServiceImpl.class | ||
| }; |
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| Class<?>[] classes = { | |
| ProductServiceImpl.class, | |
| ProductParserImpl.class, | |
| FileReaderServiceImpl.class | |
| }; | |
| Class<?> clazz = getImplementation(interfaceClazz); |
where
private static Class<?> getImplementation(Class<?> interfaceClazz) {
if (interfaceClazz.isInterface()) {
return interfaceImplementations.get(interfaceClazz);
}
return interfaceClazz;
}
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