Lab Java Interfaces and Abstract Classes completed

src/A_BigDecimal_Operations/B02_BigDecimalUtils.java

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+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
+/**
+ * B02_BigDecimalUtils — Utility methods for BigDecimal operations.
+ * Section 1 of the lab.
+ */
+public class B02_BigDecimalUtils {
+
+    /**
+     * Rounds a BigDecimal to the nearest hundredth (2 decimal places).
+     * Example: 4.2545 -> 4.25
+     * @param value the BigDecimal to round
+     * @return a double rounded to 2 decimal places
+     */
+    public static double roundToHundredth(BigDecimal value) {
+        return value.setScale(2, RoundingMode.HALF_UP).doubleValue();
+    }
+
+    /**
+     * Reverses the sign of a BigDecimal and rounds it to the nearest tenth (1 decimal place).
+     * Example: 1.2345 -> -1.2 | -45.67 -> 45.7
+     * @param value the BigDecimal to negate and round
+     * @return a BigDecimal with reversed sign rounded to 1 decimal place
+     */
+    public static BigDecimal negateAndRoundToTenth(BigDecimal value) {
+        return value.negate().setScale(1, RoundingMode.HALF_UP);
+    }
+}

src/B01_Main.java

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+import java.math.BigDecimal;
+
+
+/**
+ * B01_Main — Entry point for Lab 3: Interfaces and Abstract Classes.
+ * Runs demonstrations for all four sections.
+ */
+public class B01_Main {
+
+    public static void main(String[] args) {
+
+        // Section 1: BigDecimal Operations
+        System.out.println("=== BigDecimal Operations ===");
+        BigDecimal val1 = new BigDecimal("4.2545");
+        BigDecimal val2 = new BigDecimal("1.2345");
+        BigDecimal val3 = new BigDecimal("-45.67");
+        System.out.println(B02_BigDecimalUtils.roundToHundredth(val1));   // 4.25
+        System.out.println(B02_BigDecimalUtils.negateAndRoundToTenth(val2)); // -1.2
+        System.out.println(B02_BigDecimalUtils.negateAndRoundToTenth(val3)); // 45.7
+
+        // Section 2: Car Inventory System
+        System.out.println("\n=== Car Inventory System ===");
+        B04_Sedan sedan = new B04_Sedan("1HGCM82633A123456", "Honda", "Civic", 45000);
+        B05_UtilityVehicle suv = new B05_UtilityVehicle("2T1BURHE0JC123456", "Toyota", "RAV4", 30000, true);
+        B06_Truck truck = new B06_Truck("3GCUKREC0EG123456", "Chevrolet", "Silverado", 60000, 12000.0);
+        System.out.println(sedan.getInfo());
+        System.out.println(suv.getInfo());
+        System.out.println(truck.getInfo());
+
+        // Section 3: Video Streaming Service
+        System.out.println("\n=== Video Streaming Service ===");
+        B08_TvSeries series = new B08_TvSeries("Breaking Bad", 2700, 62);
+        B09_Movie movie = new B09_Movie("Inception", 148, 8.8);
+        System.out.println(series.getInfo());
+        System.out.println(movie.getInfo());
+
+        // Section 4: IntList Interface
+        System.out.println("\n=== IntList Interface ===");
+        B11_IntArrayList arrayList = new B11_IntArrayList();
+        B12_IntVector vector = new B12_IntVector();
+
+        for (int i = 0; i < 12; i++) {
+            arrayList.add(i * 10);
+            vector.add(i * 5);
+        }
+
+        System.out.println("IntArrayList element at index 5: " + arrayList.get(5));
+        System.out.println("IntVector element at index 5: " + vector.get(5));
+    }
+}

src/B_Car_Inventory_System/B03_Car.java

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+/**
+ * B03_Car — Abstract base class for all car types in the inventory system.
+ * Section 2 of the lab.
+ * Subclasses: B04_Sedan, B05_UtilityVehicle, B06_Truck
+ */
+public abstract class B03_Car {
+
+    private String vinNumber;
+    private String make;
+    private String model;
+    private int mileage;
+
+    public B03_Car(String vinNumber, String make, String model, int mileage) {
+        this.vinNumber = vinNumber;
+        this.make = make;
+        this.model = model;
+        this.mileage = mileage;
+    }
+
+    // --- Getters and Setters ---
+
+    public String getVinNumber() { return vinNumber; }
+    public void setVinNumber(String vinNumber) { this.vinNumber = vinNumber; }
+
+    public String getMake() { return make; }
+    public void setMake(String make) { this.make = make; }
+
+    public String getModel() { return model; }
+    public void setModel(String model) { this.model = model; }
+
+    public int getMileage() { return mileage; }
+    public void setMileage(int mileage) { this.mileage = mileage; }
+
+    /**
+     * Returns a readable string with all car properties.
+     * Each subclass must implement this method.
+     */
+    public abstract String getInfo();
+}

src/B_Car_Inventory_System/B04_Sedan.java

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+/**
+ * B04_Sedan — Represents a sedan car. Extends B03_Car.
+ * No additional properties beyond the base Car class.
+ */
+public class B04_Sedan extends B03_Car {
+
+    public B04_Sedan(String vinNumber, String make, String model, int mileage) {
+        super(vinNumber, make, model, mileage);
+    }
+
+    @Override
+    public String getInfo() {
+        return "Sedan{" +
+                "vin='" + getVinNumber() + '\'' +
+                ", make='" + getMake() + '\'' +
+                ", model='" + getModel() + '\'' +
+                ", mileage=" + getMileage() +
+                '}';
+    }
+}

src/B_Car_Inventory_System/B05_UtilityVehicle.java

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+/**
+ * B05_UtilityVehicle — Represents a utility vehicle (SUV). Extends B03_Car.
+ * Additional property: fourWheelDrive (boolean)
+ */
+public class B05_UtilityVehicle extends B03_Car {
+
+    private boolean fourWheelDrive;
+
+    public B05_UtilityVehicle(String vinNumber, String make, String model, int mileage, boolean fourWheelDrive) {
+        super(vinNumber, make, model, mileage);
+        this.fourWheelDrive = fourWheelDrive;
+    }
+
+    public boolean isFourWheelDrive() { return fourWheelDrive; }
+    public void setFourWheelDrive(boolean fourWheelDrive) { this.fourWheelDrive = fourWheelDrive; }
+
+    @Override
+    public String getInfo() {
+        return "UtilityVehicle{" +
+                "vin='" + getVinNumber() + '\'' +
+                ", make='" + getMake() + '\'' +
+                ", model='" + getModel() + '\'' +
+                ", mileage=" + getMileage() +
+                ", fourWheelDrive=" + fourWheelDrive +
+                '}';
+    }
+}

src/B_Car_Inventory_System/B06_Truck.java

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+/**
+ * B06_Truck — Represents a truck. Extends B03_Car.
+ * Additional property: towingCapacity (double)
+ */
+public class B06_Truck extends B03_Car {
+
+    private double towingCapacity;
+
+    public B06_Truck(String vinNumber, String make, String model, int mileage, double towingCapacity) {
+        super(vinNumber, make, model, mileage);
+        this.towingCapacity = towingCapacity;
+    }
+
+    public double getTowingCapacity() { return towingCapacity; }
+    public void setTowingCapacity(double towingCapacity) { this.towingCapacity = towingCapacity; }
+
+    @Override
+    public String getInfo() {
+        return "Truck{" +
+                "vin='" + getVinNumber() + '\'' +
+                ", make='" + getMake() + '\'' +
+                ", model='" + getModel() + '\'' +
+                ", mileage=" + getMileage() +
+                ", towingCapacity=" + towingCapacity +
+                '}';
+    }
+}

src/C_Video_Streaming_Service/B07_Video.java

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+/**
+ * B07_Video — Abstract base class for all video types in the streaming service.
+ * Section 3 of the lab.
+ * Subclasses: B08_TvSeries, B09_Movie
+ */
+public abstract class B07_Video {
+
+    private String title;
+    private int duration; // in minutes
+
+    public B07_Video(String title, int duration) {
+        this.title = title;
+        this.duration = duration;
+    }
+
+    // --- Getters and Setters ---
+
+    public String getTitle() { return title; }
+    public void setTitle(String title) { this.title = title; }
+
+    public int getDuration() { return duration; }
+    public void setDuration(int duration) { this.duration = duration; }
+
+    /**
+     * Returns a readable string with all video properties.
+     * Each subclass must implement this method.
+     */
+    public abstract String getInfo();
+}

src/C_Video_Streaming_Service/B08_TvSeries.java

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+/**
+ * B08_TvSeries — Represents a TV series. Extends B07_Video.
+ * Additional property: episodes (int)
+ */
+public class B08_TvSeries extends B07_Video {
+
+    private int episodes;
+
+    public B08_TvSeries(String title, int duration, int episodes) {
+        super(title, duration);
+        this.episodes = episodes;
+    }
+
+    public int getEpisodes() { return episodes; }
+    public void setEpisodes(int episodes) { this.episodes = episodes; }
+
+    @Override
+    public String getInfo() {
+        return "TvSeries{" +
+                "title='" + getTitle() + '\'' +
+                ", duration=" + getDuration() + "min" +
+                ", episodes=" + episodes +
+                '}';
+    }
+}

src/C_Video_Streaming_Service/B09_Movie.java

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+/**
+ * B09_Movie — Represents a movie. Extends B07_Video.
+ * Additional property: rating (double)
+ */
+public class B09_Movie extends B07_Video {
+
+    private double rating;
+
+    public B09_Movie(String title, int duration, double rating) {
+        super(title, duration);
+        this.rating = rating;
+    }
+
+    public double getRating() { return rating; }
+    public void setRating(double rating) { this.rating = rating; }
+
+    @Override
+    public String getInfo() {
+        return "Movie{" +
+                "title='" + getTitle() + '\'' +
+                ", duration=" + getDuration() + "min" +
+                ", rating=" + rating +
+                '}';
+    }
+}

src/D_IntList_Interface/B10_IntList.java

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+/**
+ * B10_IntList — Interface defining the contract for integer list implementations.
+ * Section 4 of the lab.
+ * Implementations: B11_IntArrayList, B12_IntVector
+ */
+public interface B10_IntList {
+
+    /**
+     * Adds a new integer to the list.
+     * Implementations must handle array resizing when full.
+     * @param number the integer to add
+     */
+    void add(int number);
+
+    /**
+     * Retrieves an element by its index.
+     * @param id the index of the element
+     * @return the integer at the given index
+     */
+    int get(int id);
+}