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solution number one #1261

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f729645
solution number one
Jul 15, 2026
a7725fd
solution number two
Jul 15, 2026
a7f9d4a
solution number two again
Jul 15, 2026
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7 changes: 7 additions & 0 deletions src/main/java/mate.academy/lib/Component.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,12 @@
package mate.academy.lib;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Component {

}
7 changes: 7 additions & 0 deletions src/main/java/mate.academy/lib/Inject.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,12 @@
package mate.academy.lib;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Inject {

}
46 changes: 45 additions & 1 deletion src/main/java/mate.academy/lib/Injector.java
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Original file line number Diff line number Diff line change
@@ -1,13 +1,57 @@
package mate.academy.lib;

import java.lang.reflect.Field;
import java.util.Map;
import mate.academy.service.FileReaderService;
import mate.academy.service.ProductParser;
import mate.academy.service.ProductService;
import mate.academy.service.impl.FileReaderServiceImpl;
import mate.academy.service.impl.ProductParserImpl;
import mate.academy.service.impl.ProductServiceImpl;

public class Injector {
private static final Injector injector = new Injector();

private final Map<Class<?>, Class<?>> interfacesImpl = Map.of(
ProductService.class, ProductServiceImpl.class,
ProductParser.class, ProductParserImpl.class,
FileReaderService.class, FileReaderServiceImpl.class);

public static Injector getInjector() {
return injector;
}

public Object getInstance(Class<?> interfaceClazz) {
return null;
Class<?> implementationClass = interfacesImpl.get(interfaceClazz);

if (implementationClass == null) {
throw new RuntimeException(
"No implementation class found for " + interfaceClazz.getName());
}

if (!implementationClass.isAnnotationPresent(Component.class)) {
throw new RuntimeException(
"No @Component annotation found for " + interfaceClazz.getName());
Comment on lines +33 to +34

@mateacademy-ai-mentor mateacademy-ai-mentor Jul 15, 2026

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The error message here uses interfaceClazz.getName(), so when @Component is missing on the implementation class, the message will still mention the interface. While not a checklist violation, updating this to use implementationClass.getName() would better match the guidance about making the message refer to the actual implementation class for clearer debugging.

}

try {
Object instance = implementationClass.getDeclaredConstructor().newInstance();

Field[] fields = implementationClass.getDeclaredFields();

for (Field field : fields) {
if (field.isAnnotationPresent(Inject.class)) {
Object dependency = getInstance(field.getType());

field.setAccessible(true);
field.set(instance, dependency);
}
}

return instance;

} catch (ReflectiveOperationException e) {
throw new RuntimeException("Unable to instantiate " + implementationClass.getName(), e);
}
}
}
2 changes: 2 additions & 0 deletions src/main/java/mate.academy/service/impl/FileReaderServiceImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,10 @@
import java.io.IOException;
import java.nio.file.Files;
import java.util.List;
import mate.academy.lib.Component;
import mate.academy.service.FileReaderService;

@Component
public class FileReaderServiceImpl implements FileReaderService {
@Override
public List<String> readFile(String fileName) {
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2 changes: 2 additions & 0 deletions src/main/java/mate.academy/service/impl/ProductParserImpl.java
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Original file line number Diff line number Diff line change
@@ -1,9 +1,11 @@
package mate.academy.service.impl;

import java.math.BigDecimal;
import mate.academy.lib.Component;
import mate.academy.model.Product;
import mate.academy.service.ProductParser;

@Component
public class ProductParserImpl implements ProductParser {
public static final int ID_POSITION = 0;
public static final int NAME_POSITION = 1;
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5 changes: 5 additions & 0 deletions src/main/java/mate.academy/service/impl/ProductServiceImpl.java
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Expand Up @@ -2,13 +2,18 @@

import java.util.List;
import java.util.stream.Collectors;
import mate.academy.lib.Component;
import mate.academy.lib.Inject;
import mate.academy.model.Product;
import mate.academy.service.FileReaderService;
import mate.academy.service.ProductParser;
import mate.academy.service.ProductService;

@Component
public class ProductServiceImpl implements ProductService {
@Inject
private ProductParser productParser;
@Inject
private FileReaderService fileReaderService;

@Override
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