diff --git a/src/main/java/rosario/exercises/exercise_08_methods/ex08_1_exercise/Item.java b/src/main/java/rosario/exercises/exercise_08_methods/ex08_1_exercise/Item.java
new file mode 100644
index 0000000..18841ad
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_08_methods/ex08_1_exercise/Item.java
@@ -0,0 +1,15 @@
+
+package rosario.exercises.exercise_08_methods.ex08_1_exercise;
+
+public class Item {
+    char color;
+    public boolean setColor(char colorCode){
+        if(colorCode == ' '){
+            return false;
+        }else{
+            this.color = colorCode;
+            return true;
+        }
+    }
+    
+}
diff --git a/src/main/java/rosario/exercises/exercise_08_methods/ex08_1_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_08_methods/ex08_1_exercise/ShoppingCart.java
new file mode 100644
index 0000000..b71ff7e
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_08_methods/ex08_1_exercise/ShoppingCart.java
@@ -0,0 +1,13 @@
+
+package rosario.exercises.exercise_08_methods.ex08_1_exercise;
+
+public class ShoppingCart {
+    public static void main(String[] args){
+        Item item1 = new Item();
+        if(/*item1.setColor(' ')*/item1.setColor('U')){
+            System.out.println(item1.color);
+        }else{
+            System.out.println("Invalid color.");
+        }
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_08_methods/ex08_2_exercise/Item.java b/src/main/java/rosario/exercises/exercise_08_methods/ex08_2_exercise/Item.java
new file mode 100644
index 0000000..02cb678
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_08_methods/ex08_2_exercise/Item.java
@@ -0,0 +1,32 @@
+
+package rosario.exercises.exercise_08_methods.ex08_2_exercise;
+
+
+public class Item {
+    String desc;
+    int quantity;
+    double price;
+    char colorCode = 'U';   //'U' = Undetermined
+
+    public void displayItem() {
+        System.out.println("Item: " + desc + ", " + quantity + ", "
+                + price + ", "+colorCode);
+    }
+
+    public void setItemFields(String desc, int quantity, double price) {
+        this.desc = desc;
+        this.quantity = quantity;
+        this.price = price;
+    }
+
+    public int setItemFields(String desc, int quantity, double price, char colorCode) {
+        if(colorCode == ' '){
+            return -1;
+        }else{
+            this.setItemFields(desc, quantity, price);
+            this.colorCode = colorCode;
+            return 1;
+        }
+    }
+    
+}
diff --git a/src/main/java/rosario/exercises/exercise_08_methods/ex08_2_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_08_methods/ex08_2_exercise/ShoppingCart.java
new file mode 100644
index 0000000..7204128
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_08_methods/ex08_2_exercise/ShoppingCart.java
@@ -0,0 +1,27 @@
+
+package rosario.exercises.exercise_08_methods.ex08_2_exercise;
+
+
+public class ShoppingCart {
+    public static void main(String[] args) {
+        Item item1 = new Item();
+        item1.setItemFields("hola",2,50.0);
+        item1.displayItem();
+
+        // case valid
+        if(item1.setItemFields("adios", 3, 100.0,'A') < 0){
+            System.out.println("Invalid Color");
+        }else{
+            item1.displayItem();
+        }
+
+        // Case invalid
+        //if(item1.setItemFields("adios", 3, 100.0,' ') < 0){
+            //System.out.println("Invalid Color");
+        //}else{
+          //  item1.displayItem();
+        //}
+
+    }
+
+}
diff --git a/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_1_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_1_exercise/ShoppingCart.java
new file mode 100644
index 0000000..5e3a8e3
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_1_exercise/ShoppingCart.java
@@ -0,0 +1,21 @@
+package rosario.exercises.exercise_09_encapconstructors.ex09_1_exercise;
+
+/**
+ * Created by rosario
+ */
+public class ShoppingCart {
+    private String name;
+    private String ssn;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getSsn() {
+        return ssn;
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_2_exercise/Customer.java b/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_2_exercise/Customer.java
new file mode 100644
index 0000000..f23dbf7
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_2_exercise/Customer.java
@@ -0,0 +1,25 @@
+package rosario.exercises.exercise_09_encapconstructors.ex09_2_exercise;
+
+/**
+ * Created by rosario
+ */
+public class Customer {
+    private String name;
+    private String ssn;
+
+    public Customer(String name, String ssn){
+        this.name = name;
+        this.ssn = ssn;
+    }
+
+    public String getName(){
+        return name;
+    }
+    public void setName(String n){
+        name = n;
+    }
+
+    public String getSSN(){
+        return ssn;
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_2_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_2_exercise/ShoppingCart.java
new file mode 100644
index 0000000..426c758
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_09_encapconstructors/ex09_2_exercise/ShoppingCart.java
@@ -0,0 +1,13 @@
+package rosario.exercises.exercise_09_encapconstructors.ex09_2_exercise;
+
+/**
+ * Created by rosario
+ */
+public class ShoppingCart {
+    public static void main(String args[]) {
+        Customer customer = new Customer("Rosario", "CUER931007MTLRSS08");
+        System.out.println(customer.getName());
+        System.out.println(customer.getSSN());
+
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_10_conditions/ex10_1_exercise/TestClass.java b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_1_exercise/TestClass.java
new file mode 100644
index 0000000..02482ce
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_1_exercise/TestClass.java
@@ -0,0 +1,21 @@
+
+package rosario.exercises.exercise_10_conditions.ex10_1_exercise;
+
+
+public class TestClass {
+
+    public static void main(String args[]) {
+        int x = 4, y = 9;
+        if (y / x < 3) {
+            x += y;
+        } else {
+            x *= y;
+        }
+        System.out.println("After if stmt, x = " + x);
+        
+        //Operator ternary
+        x = y/x<3?(x += y):(x *= y);
+        System.out.println("Operator ternary, x = " + x);
+
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_10_conditions/ex10_2_exercise/Order.java b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_2_exercise/Order.java
new file mode 100644
index 0000000..cef1663
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_2_exercise/Order.java
@@ -0,0 +1,47 @@
+
+package rosario.exercises.exercise_10_conditions.ex10_2_exercise;
+
+public class Order {
+
+    static final char CORP = 'C';
+    static final char PRIVATE = 'P';
+    static final char NONPROFIT = 'N';
+    String name;
+    double total;
+    String stateCode;
+    double discount;
+    char custType;
+
+    public Order(String name, double total, String state, char custType) {
+        this.name = name;
+        this.total = total;
+        this.stateCode = state;
+        this.custType = custType;
+        calcDiscount();
+    }
+
+    public String getDiscount() {
+        return Double.toString(discount) + "%";
+    }
+
+    // Code the calcDiscount method.
+    public void calcDiscount() {
+        if (total > 900) {
+            if (NONPROFIT == custType) {
+                discount = 10.0;
+            } else if (PRIVATE == custType) {
+                discount = 7.0;
+            }
+        } else if (CORP == custType && total < 500) {
+            discount = 8.0;
+        } else if (total < 900) {
+            if (NONPROFIT == custType) {
+                discount = 5.0;
+            } else if (PRIVATE == custType) {
+                discount = 0.0;
+            } else if (CORP == custType && total > 500) {
+                discount = 5.0;
+            }
+        }
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_10_conditions/ex10_2_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_2_exercise/ShoppingCart.java
new file mode 100644
index 0000000..6fdc86f
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_2_exercise/ShoppingCart.java
@@ -0,0 +1,9 @@
+
+package rosario.exercises.exercise_10_conditions.ex10_2_exercise;
+
+public class ShoppingCart {
+    public static void main(String args[]){
+        Order order = new Order("Rick Wilson", 1000, "VA", Order.CORP);
+        System.out.println("Discount is: "+ order.getDiscount());
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_10_conditions/ex10_3_exercise/Order.java b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_3_exercise/Order.java
new file mode 100644
index 0000000..da6a7e6
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_3_exercise/Order.java
@@ -0,0 +1,55 @@
+
+package rosario.exercises.exercise_10_conditions.ex10_3_exercise;
+
+public class Order {
+    static final char CORP = 'C';
+    static final char PRIVATE = 'P';
+    static final char NONPROFIT = 'N';
+    String name;
+    double total;
+    String stateCode;
+    double discount;
+    char custType;
+
+    public Order(String name, double total, String state, char custType) {
+        this.name = name;
+        this.total = total;
+        this.stateCode = state;
+        this.custType = custType;
+        calcDiscount();
+    }
+    
+    public String getDiscount(){
+        return Double.toString(discount) + "%";
+    }
+
+    public void calcDiscount() {
+        // Replace the if logic with a switch statement.
+        switch (custType){
+            case NONPROFIT:
+                if (total > 900) {
+                    discount = 10.00;
+                } else {
+                    discount = 5.00;
+                }
+                break;
+            case PRIVATE:
+                if (total > 900) {
+                    discount = 7.00;
+                } else {
+                    discount = 0.00;
+                }
+                break;
+            case CORP:
+                if (total < 500) {
+                    discount = 8.00;
+                } else {
+                    discount = 5.00;
+                }
+                break;
+            default:
+                discount = 0.0;
+                break;
+        }
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_10_conditions/ex10_3_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_3_exercise/ShoppingCart.java
new file mode 100644
index 0000000..acbddd5
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_10_conditions/ex10_3_exercise/ShoppingCart.java
@@ -0,0 +1,9 @@
+
+package rosario.exercises.exercise_10_conditions.ex10_3_exercise;
+
+public class ShoppingCart {
+    public static void main(String args[]){
+        Order order = new Order("Rick Wilson", 910.00, "VA", Order.NONPROFIT);
+        System.out.println("Discount is: "+ order.getDiscount());
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_1_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_1_exercise/ShoppingCart.java
new file mode 100644
index 0000000..6f89079
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_1_exercise/ShoppingCart.java
@@ -0,0 +1,17 @@
+package rosario.exercises.exercise_11_arraysloopsdates.ex11_1_exercise;
+
+import java.time.*;
+import java.time.format.DateTimeFormatter;
+
+public class ShoppingCart {
+    public static void main(String[] args) {
+        // Declare a LocalDateTime object, orderDate
+        LocalDateTime orderDate;
+        // Initialize the orderDate to the current date and time. Print it.
+        orderDate = LocalDateTime.now();
+        System.out.println(orderDate);
+        // Format orderDate using ISO_LOCAL_DATE; Print it.
+        System.out.print(orderDate.format(DateTimeFormatter.ISO_LOCAL_DATE));
+
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_2_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_2_exercise/ShoppingCart.java
new file mode 100644
index 0000000..f0f8cff
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_2_exercise/ShoppingCart.java
@@ -0,0 +1,17 @@
+
+package rosario.exercises.exercise_11_arraysloopsdates.ex11_2_exercise;
+
+public class ShoppingCart {
+    public static void main(String[] args) {
+        String name;
+        int age;
+        if(args.length <2){
+            System.out.println("2 arguments are required.");
+        }else{
+            name = args[0];
+            age = Integer.parseInt(args[1]);
+            System.out.println("name: "+name);
+            System.out.println("age: "+age);
+        }
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_3_exercise/Item.java b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_3_exercise/Item.java
new file mode 100644
index 0000000..cca332f
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_3_exercise/Item.java
@@ -0,0 +1,57 @@
+package rosario.exercises.exercise_11_arraysloopsdates.ex11_3_exercise;
+
+public class Item {
+
+    private int id;
+    private String desc;
+    private double price;
+    private boolean isBackOrdered;
+    private static int nextId = 1;
+
+    public Item(String desc, double price) {
+        setId();
+        this.desc = desc;
+        this.price = price;
+        checkStock();
+    }
+
+    private void checkStock(){  // typically would query a database here
+        
+        // Negative random numbers will result in isBackOrdered = true
+        double num = Math.random() * 1000;
+        
+        if ((int)num % 2 == 1 ){  
+            this.isBackOrdered = true;
+            System.out.println(getDesc() +" is back ordered.");
+        }
+        else this.isBackOrdered();
+    }
+
+    private void setId() {
+        id = Item.nextId++;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getDesc() {
+        return desc;
+    }
+
+    public void setDesc(String desc) {
+        this.desc = desc;
+    }
+
+    public double getPrice() {
+        return price;
+    }
+
+    public void setPrice(double price) {
+        this.price = price;
+    }
+
+    public boolean isBackOrdered() {
+        return isBackOrdered;
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_3_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_3_exercise/ShoppingCart.java
new file mode 100644
index 0000000..2ec8c80
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_3_exercise/ShoppingCart.java
@@ -0,0 +1,29 @@
+
+package rosario.exercises.exercise_11_arraysloopsdates.ex11_3_exercise;
+
+public class ShoppingCart {
+    Item[] items = {new Item("Shirt",25.60), 
+                    new Item("WristBand",0), 
+                    new Item("Pants",35.99)};
+    
+    public static void main(String[] args){
+        ShoppingCart cart = new ShoppingCart();
+        cart.displayTotal();
+    }
+    
+    // Use a standard for loop to iterate through the items array, adding up the total price
+    //    Skip any items that are back ordered.  Display the Shopping Cart total.
+    public void displayTotal(){
+        double total = 0.0;
+        for (int i = 0; i < items.length; i++) {
+            Item item = items[i];
+            if(!item.isBackOrdered()){
+                continue;
+            }else{
+                total += item.getPrice();
+            }
+        }
+        System.out.println("El total de articulos es: "+ total);
+    }
+}
+
diff --git a/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_4_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_4_exercise/ShoppingCart.java
new file mode 100644
index 0000000..029f2a9
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_11_arraysloopsdates/ex11_4_exercise/ShoppingCart.java
@@ -0,0 +1,24 @@
+package rosario.exercises.exercise_11_arraysloopsdates.ex11_4_exercise;
+
+import java.util.ArrayList;
+
+public class ShoppingCart {
+    public static void main(String[] args){   
+        // Declare, instantiate, and initialize an ArrayList of Strings.  Print and test your code.
+        ArrayList<String> arrayList = new ArrayList<>();
+        arrayList.add("Rosario");
+        arrayList.add("Cruz");
+        arrayList.add("Espinoza");
+        System.out.println(arrayList);
+        // add (insert) another element at a specific index
+        arrayList.add(0,"My name is: ");
+        System.out.println(arrayList);
+
+	// Check for the existence of a specific String element.  
+        //   If it exists, remove it.
+        if(arrayList.contains("Espinoza")){
+            arrayList.remove("Espinoza");
+        }
+        System.out.println(arrayList);
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/Item.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/Item.java
new file mode 100644
index 0000000..ee96b2a
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/Item.java
@@ -0,0 +1,51 @@
+package rosario.exercises.exercise_12_inheritance.ex12_1_exercise;
+
+public class Item {
+    private int id;
+    private String desc;
+    private double price;
+    static int nextId = 1;
+    
+    public Item(){
+    // set default values
+        setId();
+        setDesc("No description assigned.");
+        setPrice(0.00);
+    }
+    
+    public Item(String desc, double price) {
+        setId();
+        setDesc(desc);
+        setPrice(price);
+    }
+
+    public void display(){
+        System.out.println("Item description: "+getDesc());
+        System.out.println("\tID: "+getId());
+        System.out.println("\tPrice: "+getPrice());
+    }
+
+    private void setId() {
+        id = Item.nextId++;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getDesc() {
+        return desc;
+    }
+
+    private void setDesc(String desc) {
+        this.desc = desc;
+    }
+
+    public double getPrice() {
+        return price;
+    }
+
+    private void setPrice(double price) {
+        this.price = price;
+    }    
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/Shirt.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/Shirt.java
new file mode 100644
index 0000000..65b7ce3
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/Shirt.java
@@ -0,0 +1,11 @@
+package rosario.exercises.exercise_12_inheritance.ex12_1_exercise;
+
+public class Shirt extends Item {
+    private char size;
+    private char colorCode;
+    public Shirt(double price, char size, char colorCode ) {
+        super("Shirt ", price);
+        this.size = size;
+        this.colorCode = colorCode;
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/ShoppingCart.java
new file mode 100644
index 0000000..3440ed9
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_1_exercise/ShoppingCart.java
@@ -0,0 +1,11 @@
+package rosario.exercises.exercise_12_inheritance.ex12_1_exercise;
+
+public class ShoppingCart {
+    public static void main(String[] args){
+
+	// instantiate a Shirt object and call display() on the object reference
+        Shirt shirt = new Shirt(150.00,'M','U');
+        shirt.display();
+        
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/Item.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/Item.java
new file mode 100644
index 0000000..376e6b0
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/Item.java
@@ -0,0 +1,54 @@
+package rosario.exercises.exercise_12_inheritance.ex12_2_exercise;
+
+public class Item {
+    private int id;
+    private String desc;
+    private double price;
+    static int nextId = 1;
+    
+    // Default constructor sets default values
+    public Item(){
+        setId();
+        setDesc("No description assigned.");
+        setPrice(0.00);
+    }
+    
+    // Overloaded constructor takes description and price
+    public Item(String desc, double price) {
+        setId();
+        setDesc(desc);
+        setPrice(price);
+    }
+    
+    public void display(){
+        System.out.println("Item description: "+getDesc());
+        System.out.println("\tID: "+getId());
+        System.out.println("\tPrice: "+getPrice());
+    }
+
+    // Getter and Setter methods
+    private void setId() {
+        id = Item.nextId++;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getDesc() {
+        return desc;
+    }
+
+    private void setDesc(String desc) {
+        this.desc = desc;
+    }
+
+    public double getPrice() {
+        return price;
+    }
+
+    private void setPrice(double price) {
+        this.price = price;
+    }
+    
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/Shirt.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/Shirt.java
new file mode 100644
index 0000000..24ad514
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/Shirt.java
@@ -0,0 +1,20 @@
+package rosario.exercises.exercise_12_inheritance.ex12_2_exercise;
+
+public class Shirt extends Item{
+    private char size;
+    private char colorCode;
+    
+    public Shirt(double price, char size, char colorCode){
+        super ("Shirt", price);
+        this.size = size;
+        this.colorCode = colorCode;
+    } 
+    
+    // Override display() in the superclass to also show size and colorCode.
+    //   Avoid duplicating code.
+    public void display(){
+        super.display();
+        System.out.println("\tSize: "+ size);
+        System.out.println("\tColorCode: "+ colorCode);
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/ShoppingCart.java
new file mode 100644
index 0000000..3d1775d
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_2_exercise/ShoppingCart.java
@@ -0,0 +1,10 @@
+package rosario.exercises.exercise_12_inheritance.ex12_2_exercise;
+
+public class ShoppingCart {
+    public static void main(String[] args){
+        // instantiate a Shirt object and call the display() method
+        Shirt shirt = new Shirt(25.99, 'M', 'P');
+        shirt.display();
+        
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/Item.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/Item.java
new file mode 100644
index 0000000..5f3efec
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/Item.java
@@ -0,0 +1,53 @@
+package rosario.exercises.exercise_12_inheritance.ex12_3_exercise;
+
+public class Item {
+    private int id;
+    private String desc;
+    private double price;
+    static int nextId = 1;
+    
+    // Default constructor sets default values
+    public Item(){
+        setId();
+        setDesc("No description assigned.");
+        setPrice(0.00);
+    }
+    
+    // Overloaded constructor takes description and price
+    public Item(String desc, double price) {
+        setId();
+        setDesc(desc);
+        setPrice(price);
+    }
+    
+    public void display(){
+        System.out.println("Item description: "+getDesc());
+        System.out.println("\tID: "+getId());
+        System.out.println("\tPrice: "+getPrice());
+    }
+
+    // Getter and Setter methods
+    private void setId() {
+        id = Item.nextId++;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getDesc() {
+        return desc;
+    }
+
+    private void setDesc(String desc) {
+        this.desc = desc;
+    }
+
+    public double getPrice() {
+        return price;
+    }
+
+    private void setPrice(double price) {
+        this.price = price;
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/Shirt.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/Shirt.java
new file mode 100644
index 0000000..0f21b24
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/Shirt.java
@@ -0,0 +1,42 @@
+package rosario.exercises.exercise_12_inheritance.ex12_3_exercise;
+
+public class Shirt extends Item{
+    private char size;
+    private char colorCode;
+    
+    public Shirt(double price, char size, char colorCode){
+        super ("Shirt", price);
+        this.size = size;
+        this.colorCode = colorCode;
+    }
+    
+    public void display(){
+        super.display();
+        System.out.println("\tSize: "+size);
+        System.out.println("\tColorCode: "+ colorCode);
+    } 
+    
+    // Code a public getColor method that converts the colorCode to a the color name
+       // Use a switch statement.  Return the color name.
+    public String getColor(){
+        String color;
+        switch(colorCode){
+            case 'R':
+                color ="Rosa";
+                break;
+            case 'V':
+                color="Vino";
+                break;
+            case 'A':
+                color="Azul";
+                break;
+            case 'B':
+                color="Blanco";
+                break;
+            default:
+                color="No existe";
+        }
+        return color;
+    }
+
+}
diff --git a/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/ShoppingCart.java
new file mode 100644
index 0000000..26e30a5
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_12_inheritance/ex12_3_exercise/ShoppingCart.java
@@ -0,0 +1,18 @@
+package rosario.exercises.exercise_12_inheritance.ex12_3_exercise;
+
+public class ShoppingCart {
+    public static void main(String[] args) {
+         // declare and instantiate a Shirt object using an Item reference type
+        Shirt shirt = new Shirt(500.0, 'M', ' ');
+        
+        // call the display method on the object, then the getColor method
+        shirt.display();
+        if(shirt instanceof Shirt){
+            Shirt shirt1 = shirt;
+            String color = shirt1.getColor();
+            System.out.println("\tColor the shirt: "+ color);
+        }else{
+            System.out.println("\tThe object is not a Shirt");
+        }
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_1_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_1_exercise/ShoppingCart.java
new file mode 100644
index 0000000..af310d7
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_1_exercise/ShoppingCart.java
@@ -0,0 +1,26 @@
+package rosario.exercises.exercise_13_interfaces.ex13_1_exercise;
+
+
+import java.util.*;
+
+public class ShoppingCart {
+    public static void main(String[] args){
+        String[] days = {"monday","saturday","tuesday","sunday","friday"};
+
+        // Convert the days array into an ArrayList
+        List<String> listDays = new ArrayList(Arrays.asList(days));
+        // Loop through the ArrayList, printing out "sunday" elements in
+        for (String day : listDays) {
+            //   upper case (use toUpperCase() method of String class)
+            if(day.equals("sunday")){
+                System.out.println(day.toUpperCase());
+            }else{
+                // Print all other days in lower case
+                System.out.println(day);
+            }
+        }
+        // Print out the ArrayList
+        System.out.println(listDays);
+    }
+}
+
diff --git a/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Item.java b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Item.java
new file mode 100644
index 0000000..6bf1176
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Item.java
@@ -0,0 +1,69 @@
+package rosario.exercises.exercise_13_interfaces.ex13_2_exercise;
+
+public class Item {
+    private int id;
+    private String desc;
+    private double price;
+    private char colorCode;
+    static int nextId = 1;
+    
+    // Default constructor sets default values
+    public Item(){
+        setId();
+        setDesc("No description assigned.");
+        setPrice(0.00);
+        setColorCode('U');
+    }
+    
+    // Overloaded constructor takes description and price
+    public Item(String desc, double price, char cCode) {
+        setId();
+        setDesc(desc);
+        setPrice(price);
+        setColorCode(cCode);
+    }
+    
+    public void display(){
+        System.out.println("Item description: "+getDesc());
+        System.out.println("\tID: "+getId());
+        System.out.println("\tPrice: "+getPrice());
+        System.out.println("\tColor: "+getColorCode());
+    }
+
+    // Getter and Setter methods
+    private void setId() {
+        id = Item.nextId++;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getDesc() {
+        return desc;
+    }
+
+    private void setDesc(String desc) {
+        this.desc = desc;
+    }
+
+    public double getPrice() {
+        return price;
+    }
+
+    private void setPrice(double price) {
+        this.price = price;
+    }
+
+    public char getColorCode() {
+        return colorCode;
+    }
+
+    public void setColorCode(char colorCode) {
+        this.colorCode = colorCode;
+    }
+    
+    public String toString(){
+       return this.getDesc();
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Shirt.java b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Shirt.java
new file mode 100644
index 0000000..3a40e63
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Shirt.java
@@ -0,0 +1,23 @@
+package rosario.exercises.exercise_13_interfaces.ex13_2_exercise;
+
+public class Shirt extends Item{
+    private char size;
+    
+    public Shirt(double price, char size, char colorCode){
+        super ("Shirt", price, colorCode);
+        this.setSize(size);
+    }
+    
+    public void display(){
+        super.display();
+        System.out.println("\tSize: "+getSize());
+    } 
+
+    public char getSize() {
+        return size;
+    }
+
+    public void setSize(char size) {
+        this.size = size;
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/ShoppingCart.java
new file mode 100644
index 0000000..2920ea8
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/ShoppingCart.java
@@ -0,0 +1,40 @@
+package rosario.exercises.exercise_13_interfaces.ex13_2_exercise;
+
+import java.util.ArrayList;
+import java.util.function.Predicate;
+
+public class ShoppingCart {
+    ArrayList<Item> items = new ArrayList();
+    
+    public static void main(String[] args){
+        ShoppingCart cart = new ShoppingCart();
+        cart.fillCart();
+        cart.removeItemFromCart("Trousers");
+    }
+    
+    public void fillCart(){
+        items.add(new Shirt(40.95,'M','R'));
+        items.add(new Shirt(32.99,'M','Y'));
+        items.add(new Trousers(59.99,34,'B',"Relaxed",'M'));
+        items.add(new Trousers(75.50,8,'G',"Skinny",'F'));
+    }
+    
+    public void removeItemFromCart(String desc){
+        // remove all Trousers from the items list, then print out the list
+        items.removeIf(new Predicate<Item>(){
+            public boolean test(Item item){
+                if(item.getDesc().equals("Trousers")){
+                    return true;
+                }else{
+                    return false;
+                }
+            }
+        });
+
+
+        System.out.println(items);
+
+
+    }
+    
+}
diff --git a/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Trousers.java b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Trousers.java
new file mode 100644
index 0000000..82fd02f
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_13_interfaces/ex13_2_exercise/Trousers.java
@@ -0,0 +1,45 @@
+package rosario.exercises.exercise_13_interfaces.ex13_2_exercise;
+
+public class Trousers extends Item {
+    private int size;
+    private char gender;
+    private String fit;
+    
+    public Trousers(double price, int size, char colorCode, String fit,char gender){
+        super ("Trousers", price, colorCode);
+        this.setSize(size);
+        this.setGender(gender);
+        this.setFit(fit);
+    }
+    
+    public void display(){
+        super.display();
+        System.out.println("\tSize: "+getSize());
+        System.out.println("\tGender: "+ getGender());
+        System.out.println("\tFit: "+ getFit());
+    }
+
+    public int getSize() {
+        return size;
+    }
+
+    public void setSize(int size) {
+        this.size = size;
+    }
+
+    public char getGender() {
+        return gender;
+    }
+
+    public void setGender(char gender) {
+        this.gender = gender;
+    }
+
+    public String getFit() {
+        return fit;
+    }
+
+    public void setFit(String fit) {
+        this.fit = fit;
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_14_exceptions/ex14_1_exercise/Calculator.java b/src/main/java/rosario/exercises/exercise_14_exceptions/ex14_1_exercise/Calculator.java
new file mode 100644
index 0000000..68d9fff
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_14_exceptions/ex14_1_exercise/Calculator.java
@@ -0,0 +1,11 @@
+package rosario.exercises.exercise_14_exceptions.ex14_1_exercise;
+
+public class Calculator {
+    public int add(int x, int y){
+        return x + y;
+    }
+    // This method could throw an ArithmeticException
+    public double divide(int x, int y){
+        return x / y;
+    }
+}
diff --git a/src/main/java/rosario/exercises/exercise_14_exceptions/ex14_1_exercise/ShoppingCart.java b/src/main/java/rosario/exercises/exercise_14_exceptions/ex14_1_exercise/ShoppingCart.java
new file mode 100644
index 0000000..c4973ed
--- /dev/null
+++ b/src/main/java/rosario/exercises/exercise_14_exceptions/ex14_1_exercise/ShoppingCart.java
@@ -0,0 +1,18 @@
+package rosario.exercises.exercise_14_exceptions.ex14_1_exercise;
+
+public class ShoppingCart {
+
+    public static void main(String[] args) {
+        Calculator calc = new Calculator();
+        int addResult = calc.add(43, 79);
+        System.out.println("Add Result: " + addResult);
+        
+        // Add exception handling to catch ArithmeticException
+        try{
+            double divResult = calc.divide(15, 5);
+            System.out.println("Division Result: " + divResult);
+        }catch(ArithmeticException e){
+            e.printStackTrace(System.err);
+        }
+    }
+}