JavaDependencyInjection

src/main/java/mate.academy/Main.java

@@ -1,17 +1,12 @@
 package mate.academy;
 
-import java.util.List;
 import mate.academy.lib.Injector;
-import mate.academy.model.Product;
 import mate.academy.service.ProductService;
 
 public class Main {
-
     public static void main(String[] args) {
-        // Please test your Injector here. Feel free to push this class as a part of your solution
         Injector injector = Injector.getInjector();
-        ProductService productService = null;
-        List<Product> products = productService.getAllFromFile("products.txt");
-        products.forEach(System.out::println);
+        ProductService productService = injector.getInstance(ProductService.class);
+        productService.getAllFromFile("products.txt").forEach(System.out::println);
     }
 }

src/main/java/mate.academy/lib/Component.java

@@ -1,5 +1,11 @@
 package mate.academy.lib;
 
-public @interface Component {
+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 {
 }

src/main/java/mate.academy/lib/Inject.java

@@ -1,5 +1,11 @@
 package mate.academy.lib;
 
-public @interface Inject {
+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 {
 }

src/main/java/mate.academy/lib/Injector.java

@@ -1,13 +1,57 @@
 package mate.academy.lib;
 
+import java.lang.reflect.Field;
+import java.util.HashMap;
+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 Map<Class<?>, Class<?>> interfaceToImplementation = new HashMap<>();
+    private static final Map<Class<?>, Object> instances = new HashMap<>();
     private static final Injector injector = new Injector();
 
+    static {
+        interfaceToImplementation.put(ProductService.class, ProductServiceImpl.class);
+        interfaceToImplementation.put(ProductParser.class, ProductParserImpl.class);
+        interfaceToImplementation.put(FileReaderService.class, FileReaderServiceImpl.class);
+    }
+
+    private Injector() {
+    }
+
     public static Injector getInjector() {
         return injector;
     }
 
-    public Object getInstance(Class<?> interfaceClazz) {
-        return null;
+    public <T> T getInstance(Class<T> interfaceClazz) {
+        Class<?> implClass = interfaceToImplementation.get(interfaceClazz);
+        if (implClass == null) {
+            throw new RuntimeException("No implementation found for " + interfaceClazz.getName());
+        }
+        if (!implClass.isAnnotationPresent(Component.class)) {
+            throw new RuntimeException("Implementation " + implClass.getName()
+                    + " is not annotated with @Component");
+        }
+        if (instances.containsKey(implClass)) {
+            return (T) instances.get(implClass);
+        }
+        try {
+            T instance = (T) implClass.getDeclaredConstructor().newInstance();
+            for (Field field : implClass.getDeclaredFields()) {
+                if (field.isAnnotationPresent(Inject.class)) {
+                    field.setAccessible(true);
+                    field.set(instance, getInstance(field.getType()));
+                }
+            }
+            instances.put(implClass, instance);
+            return instance;
+        } catch (Exception e) {
+            throw new RuntimeException("Can't create instance of " + implClass.getName(), e);
+        }
     }
 }

src/main/java/mate.academy/model/Product.java

@@ -3,19 +3,9 @@
 import java.math.BigDecimal;
 
 public class Product {
-    private Long id;
     private String name;
-    private String category;
-    private String description;
     private BigDecimal price;
-
-    public Long getId() {
-        return id;
-    }
-
-    public void setId(Long id) {
-        this.id = id;
-    }
+    private String description;
 
     public String getName() {
         return name;
@@ -25,12 +15,12 @@ public void setName(String name) {
         this.name = name;
     }
 
-    public String getCategory() {
-        return category;
+    public BigDecimal getPrice() {
+        return price;
     }
 
-    public void setCategory(String category) {
-        this.category = category;
+    public void setPrice(BigDecimal price) {
+        this.price = price;
     }
 
     public String getDescription() {
@@ -40,23 +30,4 @@ public String getDescription() {
     public void setDescription(String description) {
         this.description = description;
     }
-
-    public BigDecimal getPrice() {
-        return price;
-    }
-
-    public void setPrice(BigDecimal price) {
-        this.price = price;
-    }
-
-    @Override
-    public String toString() {
-        return "Product{"
-                + "id=" + id
-                + ", name='" + name + '\''
-                + ", category='" + category + '\''
-                + ", description='" + description + '\''
-                + ", price=" + price
-                + '}';
-    }
 }

src/main/java/mate.academy/service/ProductParser.java

@@ -4,10 +4,9 @@
 
 public interface ProductParser {
     /**
-     * Parse the productInfo and return created {@link Product} object.
-     * The `productInfo` could be received from any source.
-     * For example from file with all products stored in the shop.
-     * @param productInfo - the information about a product
+     * Parses a product from a string.
+     *
+     * @param productInfo the string containing product information
      * @return newly create {@link Product} object based on the `productInfo` input.
      */
     Product parse(String productInfo);

src/main/java/mate.academy/service/impl/FileReaderServiceImpl.java

@@ -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) {

src/main/java/mate.academy/service/impl/ProductParserImpl.java

@@ -1,25 +1,23 @@
 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;
-    public static final int CATEGORY_POSITION = 2;
-    public static final int DESCRIPTION_POSITION = 3;
-    public static final int PRICE_POSITION = 4;
+    private static final int NAME_POSITION = 0;
+    private static final int PRICE_POSITION = 1;
+    private static final int DESCRIPTION_POSITION = 2;
 
     @Override
     public Product parse(String productInfo) {
         String[] data = productInfo.split(",");
         Product product = new Product();
-        product.setId(Long.valueOf(data[ID_POSITION]));
         product.setName(data[NAME_POSITION]);
-        product.setCategory(data[CATEGORY_POSITION]);
-        product.setDescription(data[DESCRIPTION_POSITION]);
         product.setPrice(new BigDecimal(data[PRICE_POSITION]));
+        product.setDescription(data[DESCRIPTION_POSITION]);
         return product;
     }
 }

src/main/java/mate.academy/service/impl/ProductServiceImpl.java

@@ -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