From af795b264b6511ee606600899822eadc6d01d604 Mon Sep 17 00:00:00 2001
From: Ngo Xuan Thiep <ngothiep2412@gmail.com>
Date: Wed, 6 Nov 2024 10:59:01 +0700
Subject: [PATCH 1/2] lecture1: resolve excersise

---
 .idea/gradle.xml                               |  1 +
 .idea/misc.xml                                 |  4 ++--
 .idea/saveactions_settings.xml                 | 16 ++++++++++++++++
 .../rxmobileteam/lecture1/Exercise1Main.java   | 13 ++++++++-----
 .../rxmobileteam/lecture1/data/ProductDao.java |  8 +++-----
 .../factory/ProductServiceFactory.java         |  6 ++++--
 .../rxmobileteam/lecture1/service/Product.java | 16 ++++++++++++++++
 .../lecture1/service/ProductService.java       | 18 +++++++++++++-----
 8 files changed, 63 insertions(+), 19 deletions(-)
 create mode 100644 .idea/saveactions_settings.xml

diff --git a/.idea/gradle.xml b/.idea/gradle.xml
index ce1c62c..52ca5e2 100644
--- a/.idea/gradle.xml
+++ b/.idea/gradle.xml
@@ -5,6 +5,7 @@
     <option name="linkedExternalProjectsSettings">
       <GradleProjectSettings>
         <option name="externalProjectPath" value="$PROJECT_DIR$" />
+        <option name="gradleJvm" value="corretto-11" />
         <option name="modules">
           <set>
             <option value="$PROJECT_DIR$" />
diff --git a/.idea/misc.xml b/.idea/misc.xml
index 109ff68..f68e7a6 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_19" default="true" project-jdk-name="zulu-19" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_19" project-jdk-name="zulu-19" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>
-</project>
+</project>
\ No newline at end of file
diff --git a/.idea/saveactions_settings.xml b/.idea/saveactions_settings.xml
new file mode 100644
index 0000000..5a730f0
--- /dev/null
+++ b/.idea/saveactions_settings.xml
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="SaveActionSettings">
+    <option name="actions">
+      <set>
+        <option value="activate" />
+        <option value="activateOnShortcut" />
+        <option value="activateOnBatch" />
+        <option value="organizeImports" />
+        <option value="reformat" />
+        <option value="rearrange" />
+      </set>
+    </option>
+    <option name="configurationPath" value="" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/src/main/java/com/rxmobileteam/lecture1/Exercise1Main.java b/src/main/java/com/rxmobileteam/lecture1/Exercise1Main.java
index caabeaa..2000726 100644
--- a/src/main/java/com/rxmobileteam/lecture1/Exercise1Main.java
+++ b/src/main/java/com/rxmobileteam/lecture1/Exercise1Main.java
@@ -4,6 +4,8 @@
 import com.rxmobileteam.lecture1.service.Product;
 import com.rxmobileteam.lecture1.service.ProductService;
 
+import java.util.stream.Collectors;
+
 public class Exercise1Main {
     public static void main(String[] args) {
         ProductService productService = new ProductServiceFactory().createProductService();
@@ -47,14 +49,15 @@ public static void main(String[] args) {
         productService.addProduct(samsungGalaxyS21);
         productService.addProduct(samsungGalaxyS21Ultra);
 
-        System.out.println("Search for 'Samsung':");
+        String query = "Samsung";
+        System.out.printf("Search for %s: \n", query);
+        System.out.print("Result: ");
+        System.out.println(productService.searchProducts(query).size());
         System.out.println(
             String.join(
                 "\n",
-                productService.searchProducts("Samsung")
-                    .stream()
-                    .map(Product::toString)
-                    .toList()
+                productService.searchProducts(query)
+                    .stream().map(Product::toString).collect(Collectors.toSet())
             )
         );
     }
diff --git a/src/main/java/com/rxmobileteam/lecture1/data/ProductDao.java b/src/main/java/com/rxmobileteam/lecture1/data/ProductDao.java
index 18f4a3b..cd011f1 100644
--- a/src/main/java/com/rxmobileteam/lecture1/data/ProductDao.java
+++ b/src/main/java/com/rxmobileteam/lecture1/data/ProductDao.java
@@ -6,6 +6,7 @@
 
 import java.util.HashSet;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
  * {@link ProductDao} represents a Data Access Object (DAO) for products.
@@ -24,8 +25,7 @@ public class ProductDao {
      * @return {@code true} if a product was stored, {@code false} otherwise
      */
     public boolean add(@NotNull Product product) {
-        // TODO: implement this method
-        throw new ExerciseNotCompletedException();
+        return products.add(product);
     }
 
     /**
@@ -35,8 +35,6 @@ public boolean add(@NotNull Product product) {
      */
     @NotNull
     public Set<Product> findAll() {
-        // TODO: implement this method
-        throw new ExerciseNotCompletedException();
+        return new HashSet<>(products);
     }
-
 }
diff --git a/src/main/java/com/rxmobileteam/lecture1/factory/ProductServiceFactory.java b/src/main/java/com/rxmobileteam/lecture1/factory/ProductServiceFactory.java
index ed021e4..7905819 100644
--- a/src/main/java/com/rxmobileteam/lecture1/factory/ProductServiceFactory.java
+++ b/src/main/java/com/rxmobileteam/lecture1/factory/ProductServiceFactory.java
@@ -1,5 +1,6 @@
 package com.rxmobileteam.lecture1.factory;
 
+import com.rxmobileteam.lecture1.data.ProductDao;
 import com.rxmobileteam.lecture1.service.ProductService;
 import com.rxmobileteam.utils.ExerciseNotCompletedException;
 import org.jetbrains.annotations.NotNull;
@@ -18,7 +19,8 @@ public class ProductServiceFactory {
      */
     @NotNull
     public ProductService createProductService() {
-        // TODO: implement this method
-        throw new ExerciseNotCompletedException();
+        ProductDao productDao = new ProductDao();
+
+        return new ProductService(productDao);
     }
 }
diff --git a/src/main/java/com/rxmobileteam/lecture1/service/Product.java b/src/main/java/com/rxmobileteam/lecture1/service/Product.java
index ffd6c84..adbd133 100644
--- a/src/main/java/com/rxmobileteam/lecture1/service/Product.java
+++ b/src/main/java/com/rxmobileteam/lecture1/service/Product.java
@@ -55,4 +55,20 @@ public String toString() {
             ", price=" + price +
             '}';
     }
+
+    public @NotNull String getId() {
+        return id;
+    }
+
+    public @NotNull String getName() {
+        return name;
+    }
+
+    public @NotNull String getDescription() {
+        return description;
+    }
+
+    public double getPrice() {
+        return price;
+    }
 }
diff --git a/src/main/java/com/rxmobileteam/lecture1/service/ProductService.java b/src/main/java/com/rxmobileteam/lecture1/service/ProductService.java
index b171cc1..7387b21 100644
--- a/src/main/java/com/rxmobileteam/lecture1/service/ProductService.java
+++ b/src/main/java/com/rxmobileteam/lecture1/service/ProductService.java
@@ -1,10 +1,11 @@
 package com.rxmobileteam.lecture1.service;
 
 import com.rxmobileteam.lecture1.data.ProductDao;
-import com.rxmobileteam.utils.ExerciseNotCompletedException;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
  * {@link ProductService} provides an API that allows to manage {@link Product}s.
@@ -13,6 +14,11 @@
  * TODO: 2. Using {@link ProductDao} implement method {@link ProductService#searchProducts(String)}
  */
 public class ProductService {
+    private final ProductDao productDao;
+
+    public ProductService(ProductDao productDao) {
+        this.productDao = productDao;
+    }
 
     /**
      * Adds a new product to the system.
@@ -21,8 +27,7 @@ public class ProductService {
      * @return {@code true} if a product was added, {@code false} otherwise.
      */
     public boolean addProduct(@NotNull Product product) {
-        // TODO: implement this method
-        throw new ExerciseNotCompletedException();
+        return productDao.add(product);
     }
 
     /**
@@ -33,7 +38,10 @@ public boolean addProduct(@NotNull Product product) {
      */
     @NotNull
     public List<Product> searchProducts(@NotNull String query) {
-        // TODO: implement this method
-        throw new ExerciseNotCompletedException();
+        String queryLowerCase = query.toLowerCase();
+        Set<Product> products = productDao.findAll();
+
+        return products.stream().filter(product -> product.
+            getName().toLowerCase().contains(queryLowerCase)).collect(Collectors.toList());
     }
 }

From 922c0e9aefa2ec2c23919e55e10dc0da6f0d260c Mon Sep 17 00:00:00 2001
From: Ngo Xuan Thiep <ngothiep2412@gmail.com>
Date: Wed, 4 Dec 2024 18:14:55 +0700
Subject: [PATCH 2/2] resolve exercise 2

---
 .../delegated_properties/exercise.kt          | 23 +++---
 .../lecture2_3/fraction/Fraction.kt           | 81 +++++++++++++------
 .../lecture2_3/products/product.kt            | 44 +++++++---
 3 files changed, 103 insertions(+), 45 deletions(-)

diff --git a/src/main/java/com/rxmobileteam/lecture2_3/delegated_properties/exercise.kt b/src/main/java/com/rxmobileteam/lecture2_3/delegated_properties/exercise.kt
index 1905efe..2887b50 100644
--- a/src/main/java/com/rxmobileteam/lecture2_3/delegated_properties/exercise.kt
+++ b/src/main/java/com/rxmobileteam/lecture2_3/delegated_properties/exercise.kt
@@ -3,7 +3,6 @@ package com.rxmobileteam.lecture2_3.delegated_properties
 import com.rxmobileteam.lecture2_3.delegated_properties.StringOperationDelegates.capitalized
 import com.rxmobileteam.lecture2_3.delegated_properties.StringOperationDelegates.trimmed
 import com.rxmobileteam.lecture2_3.delegated_properties.StringOperationDelegates.uppercase
-import com.rxmobileteam.utils.ExerciseNotCompletedException
 import java.util.*
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
@@ -16,14 +15,17 @@ object StringOperationDelegates {
   fun uppercase(initial: String, locale: Locale = Locale.ROOT): ReadWriteProperty<Any?, String> =
     // TODO: Implement the delegate. Note: avoid unnecessary operations/computations as much as possible
     object : ReadWriteProperty<Any?, String> {
-      private var uppercaseValue: String = throw ExerciseNotCompletedException()
+      private var uppercaseValue: String = initial.uppercase(locale)
 
       // TODO: Implement the getValue
-      override fun getValue(thisRef: Any?, property: KProperty<*>): String = throw ExerciseNotCompletedException()
+      override
+
+      fun getValue(thisRef: Any?, property: KProperty<*>): String = uppercaseValue
+
 
       // TODO: Implement the setValue
       override fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
-        throw ExerciseNotCompletedException()
+        uppercaseValue = value.uppercase()
       }
     }
 
@@ -33,14 +35,14 @@ object StringOperationDelegates {
   fun trimmed(initial: String): ReadWriteProperty<Any?, String> =
     // TODO: Implement the delegate. Note: avoid unnecessary operations/computations as much as possible
     object : ReadWriteProperty<Any?, String> {
-      private var trimmedValue: String = throw ExerciseNotCompletedException()
+      private var trimmedValue: String = initial.trim()
 
       // TODO: Implement the getValue
-      override fun getValue(thisRef: Any?, property: KProperty<*>): String = throw ExerciseNotCompletedException()
+      override fun getValue(thisRef: Any?, property: KProperty<*>): String = trimmedValue
 
       // TODO: Implement the setValue
       override fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
-        throw ExerciseNotCompletedException()
+        trimmedValue = value.trim()
       }
     }
 
@@ -50,14 +52,15 @@ object StringOperationDelegates {
   fun capitalized(initial: String): ReadWriteProperty<Any?, String> =
     // TODO: Implement the delegate. Note: avoid unnecessary operations/computations as much as possible
     object : ReadWriteProperty<Any?, String> {
-      private var value: String = throw ExerciseNotCompletedException()
+      private var value: String =
+        initial.replaceFirstChar { if (it.isLowerCase()) it.titlecase(Locale.getDefault()) else it.toString() }
 
       // TODO: Implement the getValue
-      override fun getValue(thisRef: Any?, property: KProperty<*>): String = throw ExerciseNotCompletedException()
+      override fun getValue(thisRef: Any?, property: KProperty<*>): String = value
 
       // TODO: Implement the setValue
       override fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
-        throw ExerciseNotCompletedException()
+        this.value = value.replaceFirstChar { if (it.isLowerCase()) it.titlecase() else it.toString() }
       }
     }
 }
diff --git a/src/main/java/com/rxmobileteam/lecture2_3/fraction/Fraction.kt b/src/main/java/com/rxmobileteam/lecture2_3/fraction/Fraction.kt
index 50fe226..2aadf1c 100644
--- a/src/main/java/com/rxmobileteam/lecture2_3/fraction/Fraction.kt
+++ b/src/main/java/com/rxmobileteam/lecture2_3/fraction/Fraction.kt
@@ -1,68 +1,89 @@
 package com.rxmobileteam.lecture2_3.fraction
 
 import com.rxmobileteam.utils.ExerciseNotCompletedException
+import kotlin.math.roundToInt
+import kotlin.math.roundToLong
 
 class Fraction private constructor(
   val numerator: Int,
   val denominator: Int,
 ) : Comparable<Fraction> {
   // TODO: Implement the decimal value of the fraction
-  val decimal: Double = throw ExerciseNotCompletedException()
+  val decimal: Double
+    get() = numerator.toDouble() / denominator.toDouble()
 
   init {
     // TODO: Check validity of numerator and denominator (throw an exception if invalid)
-    throw ExerciseNotCompletedException()
+    if (denominator == 0) {
+      throw IllegalArgumentException("Denominator cannot be zero")
+    }
   }
 
   //region unary operators
   // TODO: "+fraction" operator
-  operator fun unaryPlus(): Fraction = throw ExerciseNotCompletedException()
+  operator fun unaryPlus(): Fraction = Fraction(numerator, denominator)
 
   // TODO: "-fraction" operator
-  operator fun unaryMinus(): Fraction = throw ExerciseNotCompletedException()
+  operator fun unaryMinus(): Fraction = Fraction(-numerator, denominator)
   //endregion
 
   //region plus operators
   // TODO: "fraction+fraction" operator
-  operator fun plus(other: Fraction): Fraction = throw ExerciseNotCompletedException()
+  operator fun plus(other: Fraction): Fraction {
+    val commonDenominator = denominator * other.denominator
+    val newNumerator = (numerator * other.denominator) + (other.numerator * denominator)
+    return Fraction(newNumerator, commonDenominator)
+  }
 
   // TODO: "fraction+number" operator
-  operator fun plus(other: Int): Fraction = throw ExerciseNotCompletedException()
+  operator fun plus(other: Int): Fraction = this + Fraction(other, 1)
   //endregion
 
   //region times operators
   // TODO: "fraction*fraction" operator
-  operator fun times(other: Fraction): Fraction = throw ExerciseNotCompletedException()
+  operator fun times(other: Fraction): Fraction {
+    val commonDenominator = denominator * other.denominator
+    val newNumerator = numerator * other.numerator
+    return Fraction(newNumerator, commonDenominator)
+  }
 
   // TODO: "fraction*number" operator
-  operator fun times(number: Int): Fraction = throw ExerciseNotCompletedException()
+  operator fun times(number: Int): Fraction = Fraction(numerator * number, denominator)
   //endregion
 
   // TODO: Compare two fractions
-  override fun compareTo(other: Fraction): Int = throw ExerciseNotCompletedException()
+  override fun compareTo(other: Fraction): Int {
+    val thisDecimal = this.decimal
+    val otherDecimal = other.decimal
+    return thisDecimal.compareTo(otherDecimal)
+  }
 
   //region toString, hashCode, equals, copy
   // TODO: Format the fraction as a string (e.g. "1/2")
-  override fun toString(): String = throw ExerciseNotCompletedException()
+  override fun toString(): String = "$numerator/$denominator"
 
   // TODO: Implement hashCode
-  override fun hashCode(): Int = throw ExerciseNotCompletedException()
+  override fun hashCode(): Int = 31 * numerator + denominator
 
   // TODO: Implement equals
-  override fun equals(other: Any?): Boolean = throw ExerciseNotCompletedException()
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    if (other !is Fraction) return false
+    return (numerator == other.numerator) && (denominator == other.denominator)
+  }
 
   // TODO: Implement copy
   fun copy(
     numerator: Int = this.numerator,
     denominator: Int = this.denominator
-  ): Fraction = throw ExerciseNotCompletedException()
+  ): Fraction = Fraction(numerator, denominator)
   //endregion
 
   companion object {
     @JvmStatic
     fun ofInt(number: Int): Fraction {
       // TODO: Returns a fraction from an integer number
-      throw ExerciseNotCompletedException()
+      return Fraction(number, 1)
     }
 
     @JvmStatic
@@ -70,40 +91,54 @@ class Fraction private constructor(
       // TODO: Check validity of numerator and denominator
       // TODO: Simplify fraction using the greatest common divisor
       // TODO: Finally, return the fraction with the correct values
-      throw ExerciseNotCompletedException()
+      if (denominator == 0) throw IllegalArgumentException("Denominator cannot be zero")
+      val gcd = gcd(numerator, denominator)
+      val simplifiedNumerator = numerator / gcd
+      val simplifiedDenominator = denominator / gcd
+      return Fraction(simplifiedNumerator, simplifiedDenominator)
+    }
+
+    private fun gcd(a: Int, b: Int): Int {
+      return if (b == 0) a else gcd(b, a % b)
     }
   }
 }
 
 // TODO: return a Fraction representing "this/denominator"
-infix fun Int.over(denominator: Int): Fraction = throw ExerciseNotCompletedException()
+infix fun Int.over(denominator: Int): Fraction = Fraction.of(this, denominator)
 
 //region get extensions
 // TODO: get the numerator, eg. "val (numerator) = Fraction.of(1, 2)"
-operator fun Fraction.component1(): Int = throw ExerciseNotCompletedException()
+operator fun Fraction.component1(): Int = this.numerator
 
 // TODO: get the denominator, eg. "val (_, denominator) = Fraction.of(1, 2)"
-operator fun Fraction.component2(): Int = throw ExerciseNotCompletedException()
+operator fun Fraction.component2(): Int = this.denominator
 
 // TODO: get the decimal, index must be 0 or 1
 // TODO: eg. "val numerator = Fraction.of(1, 2)[0]"
 // TODO: eg. "val denominator = Fraction.of(1, 2)[1]"
 // TODO: eg. "val denominator = Fraction.of(1, 2)[2]" should throw an exception
-operator fun Fraction.get(index: Int): Int = throw ExerciseNotCompletedException()
+operator fun Fraction.get(index: Int): Int {
+  return when(index) {
+    0 -> this.numerator
+    1 -> this.denominator
+    else -> throw IndexOutOfBoundsException("Index must be 0 or 1")
+  }
+}
 //endregion
 
 //region to number extensions
 // TODO: round to the nearest integer
-fun Fraction.roundToInt(): Int = throw ExerciseNotCompletedException()
+fun Fraction.roundToInt(): Int = this.decimal.roundToInt()
 
 // TODO: round to the nearest long
-fun Fraction.roundToLong(): Long = throw ExerciseNotCompletedException()
+fun Fraction.roundToLong(): Long = this.decimal.roundToLong()
 
 // TODO: return the decimal value as a float
-fun Fraction.toFloat(): Float = throw ExerciseNotCompletedException()
+fun Fraction.toFloat(): Float = this.decimal.toFloat()
 
 // TODO: return the decimal value as a double
-fun Fraction.toDouble(): Double = throw ExerciseNotCompletedException()
+fun Fraction.toDouble(): Double = this.decimal
 //endregion
 
 fun main() {
diff --git a/src/main/java/com/rxmobileteam/lecture2_3/products/product.kt b/src/main/java/com/rxmobileteam/lecture2_3/products/product.kt
index 2262901..cba464d 100644
--- a/src/main/java/com/rxmobileteam/lecture2_3/products/product.kt
+++ b/src/main/java/com/rxmobileteam/lecture2_3/products/product.kt
@@ -25,35 +25,55 @@ data class Order(
 )
 
 // TODO: Return a list of Product, sorted in the ascending by price. if prices are equal, sorted by favoriteCount descending
-fun List<Product>.sortedByPriceAscendingThenByFavoriteCountDescending(): List<Product> =
-  throw ExerciseNotCompletedException()
+fun List<Product>.sortedByPriceAscendingThenByFavoriteCountDescending(): List<Product> {
+  return sortedWith(compareBy<Product> { it.price }.thenByDescending { it.favoriteCount })
+}
+
 
 // TODO: Return a set of Products in the orders (The order doesn't matter).
-fun List<Order>.getProductsSet(): Set<Product> = throw ExerciseNotCompletedException()
+fun List<Order>.getProductsSet(): Set<Product> {
+  return this.flatMap { it.products }.toSet()
+}
 
 // TODO: Return a list of Products in the orders, duplicates are allowed.
-fun List<Order>.getProductsList(): List<Product> = throw ExerciseNotCompletedException()
+fun List<Order>.getProductsList(): List<Product> {
+  return this.flatMap { it.products }
+}
 
 // TODO: Return a list of delivered orders
-fun List<Order>.getDeliveredOrders(): List<Order> = throw ExerciseNotCompletedException()
+fun List<Order>.getDeliveredOrders(): List<Order> {
+  return this.filter { it.isDelivered }
+}
 
 // TODO: Return a list of products in the delivered orders
-fun List<Order>.getDeliveredProductsList(): List<Product> = throw ExerciseNotCompletedException()
+fun List<Order>.getDeliveredProductsList(): List<Product> {
+  return this.getDeliveredOrders().flatMap { it.products }
+}
 
 // TODO: Partition the orders into two lists: "delivered" and "not delivered"
-fun List<Order>.partitionDeliveredAndNotDelivered(): Pair<List<Order>, List<Order>> =
-  throw ExerciseNotCompletedException()
+fun List<Order>.partitionDeliveredAndNotDelivered(): Pair<List<Order>, List<Order>> {
+  return this.partition { it.isDelivered }
+}
+
 
 // TODO: Return a map of product to count of this product in the orders
 // eg. [Product1 -> 2, Product2 -> 1, Product3 -> 3]
-fun List<Order>.countOfEachProduct(): Map<Product, Int> = throw ExerciseNotCompletedException()
+fun List<Order>.countOfEachProduct(): Map<Product, Int> {
+  return this.flatMap { it.products }.groupingBy { it }.eachCount()
+}
 
 // TODO: Return the sum of product prices in the order
-fun Order.sumProductPrice(): Double = throw ExerciseNotCompletedException()
+fun Order.sumProductPrice(): Double {
+  return this.products.sumOf { it.price }
+}
 
 // TODO: Return the product with the maximum price in the order
-fun Order.getMaxPriceProduct(): Product = throw ExerciseNotCompletedException()
+fun Order.getMaxPriceProduct(): Product {
+  return this.products.maxByOrNull { it.price } ?: throw NoSuchElementException("No products in the order")
+}
 
 // TODO: Return the product with the min price in the order
-fun Order.getMinPriceProduct(): Product = throw ExerciseNotCompletedException()
+fun Order.getMinPriceProduct(): Product {
+  return this.products.minByOrNull { it.price } ?: throw NoSuchElementException("No products in the order")
+}