Stub out code

README.md

 # Store Lab
 * **Purpose** - to understand [HashMap](https://www.youtube.com/watch?v=shs0KM3wKv8), [objects](https://docs.oracle.com/javase/tutorial/java/concepts/object.html) and [data encapsulation](https://en.wikipedia.org/wiki/Data_encapsulation).
 
-* **Objective** - to create two type of maps
+* **Objective** - A map/associative array is a data type that allow users to search for a value. The objective of this lab is to understand how to create map and see how we store data affects how its performance.
+
 
 ## Part 1 - Equals & HashCode
-By default, every [Java object](https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html) has an [equals](https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#equals) and a [hashCode](https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#hashCode) method. Java uses the object's address to calculate the [hashCode](https://en.wikipedia.org/wiki/Hash_function). By default, two objects are equal if they have the same address. We don't want this. Two objects are equal if they are the same class and have the same values.
+By default, every [Java object](https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html) has an [equals](https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#equals) and a [hashCode](https://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#hashCode) method. Java uses the object's address to calculate the [hashCode](https://en.wikipedia.org/wiki/Hash_function). By default, two objects are equal if they have the same address. We don't want this. Two objects are equal if they are the same class and have the same values. Your task is to add the `equals` and `hashCode` to the `User` and `Cart` class.
 
   1. User
-    1. Add an `equals` method to the `User` class. The equal method should return true only if the `id` and `name` of the user are the same. It return false otherwise.
+    1. Add an `equals` method to the `User` class. The equal method should return true only if the `id` and `name` are the same. It return false otherwise.
     2. Add a `hashCode` method by calling `Objects.hash()` and gives it the `id` and `name` (e.g. `Objects.hash(id, name)`)
   2. Cart
     1. Add an `equals` and `hashCode` methods with IntelliJ shortcut
       1. Click `Command + N` and select `equals and hashCode`. Follow the wizard to generate the code.
 
-## Part 2 - ListMap
-
-
-
-
-This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language
-
-
-## Part 1 - ListMap
-In the `test` folder, there is a `ProductTest` with most of the tested commented out.
-  1. The first test `testConstruction_WithNoParams` checks to see if the `Product` class has an empty constructor. To test it, I created a new object with no parameter.
-  2. The second test `testGetSetName` checks to see if you can set and get the name of the product. In order to make this pass, I added a `String` field called `name` (line 5). Then I added a getter method `getName` (line 18-20) and a setter method `setName(String name)` (line 23-25).
-  3. The third test `testConstruction_WithName` checks if the `Product` class has a constructor that takes a String. Notice we can have more than one constructor. When I create a new Product with a string `new Product("T-shirt")`, I set that string to the field `name` so when I called `getName`, I get the string that I passed into the constructor.
-  4. Continue to uncomment the test and write the code to make it pass
-  5. For the product description, it should be in this format `title (Color: color, Size: size)`
-    - ex: `Hat (Color: Yellow, Size: LG)`
-
-## Part 2 - Cart
-A cart has an array of Product.
-  1. Open the `CartTest` and uncomment line 9-13. To make the test pass:
-    - Create a new class named `Cart`
-    - Create a new constructor that takes an array of Product
-    - Run the test, it should pass
-  2. Create a getter for Product to make `testGetProducts` test pass
-  3. To make `testGetSetDiscount` test pass:
-    - Create a new decimal field called `discount`
-    - Create a getter and setter for the field
-    - Run the test
-  4. To get `getProductTotal` tests to pass, you need add all the product prices together and return the result.
-  5. To get the total, you need to add the total of all the products minus the discount. For example, if a product costs $100, and the discount is 20% (0.20), then the total = 100 - (100 * 0.20) = 80
-
-## Part 3 - CreditCard
-The goal of this exercise is to know how to create and test a class.
-  1. In the test folder, create a new test class called `CreditCardTest`
-  2. Create a new class called `CreditCard`
-  2. Create a test case to get and set the `cardHolderName` of the type `String`
-      - Create getter and setter methods in the `CreditCard` class
-      - Add a field called cardHolderName
-  2. Do the same for the following fields:
-    - `String number`
-    - `int expiredMonth`
-    - `int expiredYear`
-  3. Create a getter and setter for each field
-  4. Create a test for `getDescription`
-    - `getDescription` should return `[cardHolderName] [last 4 digit of the number] [expiredMonth]/[expiredYear]`
-      - ex: `Tia Mowry 4551 10/2019`
-  5. Add a `CreditCard` field to the `Cart` class
-    - Add a getter and setter for the `creditCard` field
+## Map
+Details instructions on what each method should do and return is in `MyMap` class.
 
-## Part 4 - Product as an ArrayList - BONUS
-The goal of this exercise is to change the `products` array in the `Cart` class to an ArrayList.
-  1. In the `CartTest`, change the `products` array to an `ArrayList`
+### Part 2 - ListMap
+A list map stores every entry in a list. Every time the user calls `put`, create a new `Entry` and add it to the list. Your task is to make all the test pass.
+  1. Uncomment line 178 - 196. Notice how long the test takes to run.
 
-    ```java
-      ArrayList<Product> products = new ArrayList();
-      products.add(new Product("Shirt", 15.01));
-    ```
+**BONUS**: Uncomment the remove method and add the code to pass the tests.
 
-  2. Add this test to the `CartTest` class
-  ```java
-    @Test
-    public void testAddToCard(){
-        // Given
-        ArrayList<Product> products = new ArrayList();
-        Cart cart = new Cart(products);
+### Part 3 - MyHashMap
+If you still have no idea what a HashMap is, watch this [video](https://www.youtube.com/watch?v=shs0KM3wKv8). Notice I add the `bucketIndex` to help you determine where to store the entry. The `bucketIndex` uses the `hashCode` to try to evenly distribute the entries. 
+  1. `put` - find which bucket it belongs to, then add it to the list of that bucket
+  2. `get` - find which bucket it belongs to, then loop through the list to find the entry corresponding to the key
+  3. Uncomment line 178 - 196. Notice how fast it takes to run.
 
-        // When
-        Product shirt = new Product("Shirt", 1.99);
-        cart.addProduct(shirt);
+**BONUS**: Uncomment the remove method and add the code to pass the tests.
 
-        // Then
-        double expectedTotal = 1.99;
-        double actualTotal = cart.getProductTotal();
-        Assert.assertEquals(expectedTotal, actualTotal, DELTA);
-    }
-  ```
-    - Add a `addProduct` method to the `Cart` class
-    - Run the test. It should pass.
+## Performance
+Notice how long the ListMap takes to store and find 70,000 items. Notice how much faster a HashMap is. In the `MyHashMap` class, change the `BUCKET_SIZE` to `100`. Run the `MyHashMapTest` again. Notice how much faster it is. That's the power of designing and using a good data structure. It can speed up your program significantly.

src/main/java/org/zipcoder/store/Cart.java

+package org.zipcoder.store;
+
+import java.util.Objects;
+
+public class Cart {
+    private final long id;
+
+    public Cart(long id) {
+        this.id = id;
+    }
+
+    public long getId(){
+        return this.id;
+    }
+}

src/main/java/org/zipcoder/store/Entry.java

+package org.zipcoder.store;
+
+public class Entry {
+    private User key;
+    private Cart value;
+
+    public Entry(User key, Cart value) {
+        this.key = key;
+        this.value = value;
+    }
+
+    public User getKey() {
+        return key;
+    }
+
+    public Cart getValue() {
+        return value;
+    }
+
+    public void setValue(Cart value) {
+        this.value = value;
+    }
+}

src/main/java/org/zipcoder/store/ListMap.java

+package org.zipcoder.store;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ListMap implements MyMap {
+    // instance field that is intialize to an ArrayList
+    private List<Entry> entries = new ArrayList<>();
+
+    @Override
+    public int size() {
+        return -1;
+    }
+
+    @Override
+    public boolean isEmptry() {
+        return false;
+    }
+
+    @Override
+    public Cart get(User key) {
+        // find the cart associate with the key
+        return null;
+    }
+
+    @Override
+    public void put(User key, Cart value) {
+        // add the key, value entry to the entries list
+    }
+
+
+    @Override
+    public List<User> getKeys() {
+        // get all the keys in the map
+        return null;
+    }
+
+    @Override
+    public List<Cart> getValues() {
+        // get all the values in the map
+        return null;
+    }
+
+    @Override
+    public Cart remove(User key) {
+        return null;
+    }
+}

src/main/java/org/zipcoder/store/MyHashMap.java

+package org.zipcoder.store;
+
+import java.util.*;
+
+public class MyHashMap implements MyMap{
+    // final field that doesn't change for any object
+    private static final int BUCKET_SIZE = 15;
+
+    // instance field that can only be set once. It is different for every Object
+    private final List<Entry>[] entries;
+
+    public MyHashMap(){
+        entries = new List[BUCKET_SIZE];
+
+        for(int i = 0; i < BUCKET_SIZE; i++) {
+            entries[i] = new ArrayList<>();
+        }
+    }
+
+    @Override
+    public int size() {
+        return -1;
+    }
+
+    @Override
+    public boolean isEmptry() {
+        return false;
+    }
+
+    @Override
+    public Cart get(User key) {
+        return null;
+    }
+
+    @Override
+    public void put(User key, Cart value) {
+
+    }
+
+    @Override
+    public List<User> getKeys() {
+        return null;
+    }
+
+    @Override
+    public List<Cart> getValues() {
+        return null;
+    }
+
+    @Override
+    public Cart remove(User key) {
+        return null;
+    }
+
+    private int bucketIndex(User key){
+        return Math.abs(key.hashCode()) % entries.length;
+    }
+}

src/main/java/org/zipcoder/store/MyMap.java

+package org.zipcoder.store;
+
+import java.util.List;
+
+public interface MyMap {
+
+    /**
+     * @return the number of entry in the map
+     */
+    public int size();
+
+    /**
+     * @return true if the map has one or more item in it. False otherwise.
+     */
+    public boolean isEmptry();
+
+    /**
+     * Return the cart associated with the user
+     * @param key
+     * @return The cart associated with the user, null if none exist.
+     */
+    public Cart get(User key);
+
+    /**
+     * Associate the user with the cart. If user already has a cart, then replace the old cart with this one.
+     * @param key The key to associate the cart
+     * @param value The cart to be associated
+     */
+    public void put(User key, Cart value);
+
+    /**
+     * @return All the users in the map
+     */
+    public List<User> getKeys();
+
+    /**
+     * @return All the carts in the map
+     */
+    public List<Cart> getValues();
+
+    /**
+     * Remove the user & cart from the map
+     * @param key The user to remove
+     * @return The cart associated with the user
+     */
+    public Cart remove(User key);
+}

src/main/java/org/zipcoder/store/User.java

+package org.zipcoder.store;
+
+import java.util.Objects;
+
+public class User {
+
+    private long id;
+    private String name;
+
+    public User(){}
+
+    public User(long id) {
+        this.id = id;
+    }
+
+    public User(String name) {
+        this.name = name;
+    }
+
+    public User(long id, String name){
+        this.id = id;
+        this.name = name;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

src/test/java/org/zipcoder/store/EntryTest.java

+package org.zipcoder.store;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class EntryTest {
+
+    @Test
+    public void testGetKey(){
+        User key = new User();
+        Cart value = new Cart(13);
+        Entry entry = new Entry(key, value);
+
+        User actualKey = entry.getKey();
+
+        Assert.assertEquals(key, actualKey);
+    }
+
+    @Test
+    public void testGetValue(){
+        User key = new User();
+        Cart value = new Cart(54);
+        Entry entry = new Entry(key, value);
+
+        Cart actualValue = entry.getValue();
+
+        Assert.assertEquals(value, actualValue);
+    }
+
+
+    @Test
+    public void testGetSetValue(){
+        User key = new User();
+        Cart value = new Cart(54);
+        Entry entry = new Entry(key, null);
+
+        entry.setValue(value);
+        Cart actualValue = entry.getValue();
+
+        Assert.assertEquals(value, actualValue);
+    }
+}

src/test/java/org/zipcoder/store/ListMapTest.java

         Assert.assertTrue(values.contains(cart2));
     }
 
-    @Test
-    public void testPutAndGet_WithManyItems(){
-        // Given
-        for (int i = 0; i < 70000; i++) {
-            myMap.put(new User(i), new Cart(i));
-        }
-
-
-        for (int i = 0; i < 70000; i++) {
-            // When
-            Cart actualCart = myMap.get(new User(i));
-            Cart expectedCart = new Cart(i);
-
-            // Then
-            Assert.assertEquals(actualCart, expectedCart);
-        }
-    }
-
-    @Test
-    public void testRemove(){
-        // Given
-        User user1 = new User("Lena");
-        Cart cart1 = new Cart(11);
-
-        User user2 = new User("Jamal");
-        Cart cart2 = new Cart(21);
-
-        User user3 = new User("Kelvin");
-        Cart cart3 = new Cart(31);
-
-        // When
-        myMap.put(user1, cart1);
-        myMap.put(user2, cart2);
-        myMap.put(user3, cart3);
-
-        // Then
-        Cart actualCart = myMap.remove(user2);
-
-        Assert.assertEquals(cart2, actualCart);
-        Assert.assertNull(myMap.get(user2));
-    }
-
-    @Test
-    public void testRemove_CartNotInTheMap(){
-        // Given
-        User user1 = new User("Lena");
-
-        // When & Then
-        Assert.assertNull(myMap.remove(user1));
-    }
+//    I commented this out because it takes a long time to run. Uncomment it when implement your put method, uncomment this test
+//    @Test
+//    public void testPutAndGet_WithManyItems(){
+//        // Given
+//        int numberOfEntries = 70000;
+//
+//        for (int i = 0; i < numberOfEntries; i++) {
+//            myMap.put(new User(i), new Cart(i));
+//        }
+//
+//
+//        for (int i = 0; i < numberOfEntries; i++) {
+//            // When
+//            Cart actualCart = myMap.get(new User(i));
+//            Cart expectedCart = new Cart(i);
+//
+//            // Then
+//            Assert.assertEquals(actualCart, expectedCart);
+//        }
+//    }
+
+//    BONUS
+//    @Test
+//    public void testRemove(){
+//        // Given
+//        User user1 = new User("Lena");
+//        Cart cart1 = new Cart(11);
+//
+//        User user2 = new User("Jamal");
+//        Cart cart2 = new Cart(21);
+//
+//        User user3 = new User("Kelvin");
+//        Cart cart3 = new Cart(31);
+//
+//        // When
+//        myMap.put(user1, cart1);
+//        myMap.put(user2, cart2);
+//        myMap.put(user3, cart3);
+//
+//        // Then
+//        Cart actualCart = myMap.remove(user2);
+//
+//        Assert.assertEquals(cart2, actualCart);
+//        Assert.assertNull(myMap.get(user2));
+//    }
+//
+//    @Test
+//    public void testRemove_CartNotInTheMap(){
+//        // Given
+//        User user1 = new User("Lena");
+//
+//        // When & Then
+//        Assert.assertNull(myMap.remove(user1));
+//    }
 }

src/test/java/org/zipcoder/store/MyHashMapTest.java

         Assert.assertTrue(values.contains(cart2));
     }
 
-    @Test
-    public void testPutAndGet_WithManyItems(){
-        // Given
-        for (int i = 0; i < 70000; i++) {
-            myMap.put(new User(i), new Cart(i));
-        }
-
-
-        for (int i = 0; i < 70000; i++) {
-            // When
-            Cart actualCart = myMap.get(new User(i));
-            Cart expectedCart = new Cart(i);
-
-            // Then
-            Assert.assertEquals(actualCart, expectedCart);
-        }
-    }
-
-    @Test
-    public void testRemove(){
-        // Given
-        User user1 = new User("Lena");
-        Cart cart1 = new Cart(11);
-
-        User user2 = new User("Jamal");
-        Cart cart2 = new Cart(21);
-
-        User user3 = new User("Kelvin");
-        Cart cart3 = new Cart(31);
-
-        // When
-        myMap.put(user1, cart1);
-        myMap.put(user2, cart2);
-        myMap.put(user3, cart3);
-
-        // Then
-        Cart actualCart = myMap.remove(user2);
-
-        Assert.assertEquals(cart2, actualCart);
-        Assert.assertNull(myMap.get(user2));
-    }
-
-    @Test
-    public void testRemove_CartNotInTheMap(){
-        // Given
-        User user1 = new User("Lena");
-
-        // When & Then
-        Assert.assertNull(myMap.remove(user1));
-    }
+//    I commented this out because it takes a long time to run. Uncomment it when implement your put method, uncomment this test
+//    @Test
+//    public void testPutAndGet_WithManyItems(){
+//        // Given
+//        int numberOfEntries = 70000;
+//
+//        for (int i = 0; i < numberOfEntries; i++) {
+//            myMap.put(new User(i), new Cart(i));
+//        }
+//
+//
+//        for (int i = 0; i < numberOfEntries; i++) {
+//            // When
+//            Cart actualCart = myMap.get(new User(i));
+//            Cart expectedCart = new Cart(i);
+//
+//            // Then
+//            Assert.assertEquals(actualCart, expectedCart);
+//        }
+//    }
+
+//    @Test
+//    public void testRemove(){
+//        // Given
+//        User user1 = new User("Lena");
+//        Cart cart1 = new Cart(11);
+//
+//        User user2 = new User("Jamal");
+//        Cart cart2 = new Cart(21);
+//
+//        User user3 = new User("Kelvin");
+//        Cart cart3 = new Cart(31);
+//
+//        // When
+//        myMap.put(user1, cart1);
+//        myMap.put(user2, cart2);
+//        myMap.put(user3, cart3);
+//
+//        // Then
+//        Cart actualCart = myMap.remove(user2);
+//
+//        Assert.assertEquals(cart2, actualCart);
+//        Assert.assertNull(myMap.get(user2));
+//    }
+//
+//    @Test
+//    public void testRemove_CartNotInTheMap(){
+//        // Given
+//        User user1 = new User("Lena");
+//
+//        // When & Then
+//        Assert.assertNull(myMap.remove(user1));
+//    }
 }