Implementing Iterator Design Pattern

Author: akshayKhannaNow

src/main/java/iterator/AppleMobilesCollection.java

@@ -0,0 +1,23 @@
+package iterator;
+
+
+public class AppleMobilesCollection implements Collection {
+    private int index;
+    Mobile appleMobiles[];
+
+
+    public AppleMobilesCollection(int size) {
+        this.appleMobiles = new Mobile[size];
+        index = 0;
+    }
+
+    @Override
+    public Iterator createIterator() {
+        return new AppleMobilesIterator(this.appleMobiles);
+    }
+
+    @Override
+    public void add(Item item) {
+        this.appleMobiles[index++] = (Mobile) item;
+    }
+}

src/main/java/iterator/AppleMobilesIterator.java

@@ -0,0 +1,28 @@
+package iterator;
+
+import java.lang.reflect.Array;
+import java.util.List;
+
+public class AppleMobilesIterator implements Iterator {
+    private int pos;
+    private Mobile mobiles[];
+
+    public AppleMobilesIterator(Mobile[] mobiles) {
+        pos = 0;
+        this.mobiles = mobiles;
+    }
+
+    @Override
+    public boolean hasNext() {
+        if (pos >= this.mobiles.length || this.mobiles[pos] == null)
+            return false;
+        return true;
+    }
+
+    @Override
+    public Mobile next() {
+        return mobiles[this.pos++];
+    }
+
+
+}

src/main/java/iterator/Collection.java

@@ -0,0 +1,7 @@
+package iterator;
+
+public interface Collection {
+    Iterator createIterator();
+
+    void add(Item item);
+}

src/main/java/iterator/Item.java

@@ -0,0 +1,4 @@
+package iterator;
+
+public interface Item {
+}

src/main/java/iterator/Iterator.java

@@ -0,0 +1,8 @@
+package iterator;
+
+import java.util.Objects;
+
+public interface Iterator {
+    boolean hasNext();
+    Object next();
+}

src/main/java/iterator/Mobile.java

@@ -0,0 +1,19 @@
+package iterator;
+
+public class Mobile implements Item {
+    private String id;
+    private String name;
+    private int quantity;
+    private double price;
+
+    public Mobile(String id, String name, int quantity, double price) {
+        this.id = id;
+        this.name = name;
+        this.quantity = quantity;
+        this.price = price;
+    }
+
+    public double totalCost() {
+        return this.price * this.quantity;
+    }
+}

src/main/java/iterator/MobileStore.java

@@ -0,0 +1,14 @@
+package iterator;
+
+public class MobileStore {
+
+    public double getTotalInventoryCost(Collection mobilesCollection) {
+        Iterator mobilesIterator = mobilesCollection.createIterator();
+        double totalCost = 0;
+        while (mobilesIterator.hasNext()) {
+            var mobile = (Mobile) (mobilesIterator.next());
+            totalCost += mobile.totalCost();
+        }
+        return totalCost;
+    }
+}

src/main/java/iterator/SamsungMobileCollection.java

@@ -0,0 +1,23 @@
+package iterator;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public class SamsungMobileCollection implements Collection {
+
+    private final List<Mobile> mobiles;
+
+    public SamsungMobileCollection() {
+        mobiles = new LinkedList<>();
+    }
+
+    @Override
+    public Iterator createIterator() {
+        return new SamsungMobileIterator(mobiles);
+    }
+
+    @Override
+    public void add(Item item) {
+        this.mobiles.add((Mobile) item);
+    }
+}

src/main/java/iterator/SamsungMobileIterator.java

@@ -0,0 +1,25 @@
+package iterator;
+
+import java.util.List;
+
+public class SamsungMobileIterator implements Iterator {
+    private List<Mobile> mobiles;
+    private int index;
+
+    public SamsungMobileIterator(List<Mobile> mobiles) {
+        this.index = 0;
+        this.mobiles = mobiles;
+    }
+
+    @Override
+    public boolean hasNext() {
+        if(this.mobiles.isEmpty() || this.index >= this.mobiles.size())
+            return false;
+        return true;
+    }
+
+    @Override
+    public Object next() {
+        return this.mobiles.get(this.index++);
+    }
+}

src/test/java/iterator/MobileStoreTest.java

@@ -0,0 +1,43 @@
+package iterator;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class MobileStoreTest {
+
+    private MobileStore mobileStore;
+    private Collection applMobilesCollection;
+
+    @BeforeEach
+    void setUp() {
+        mobileStore = new MobileStore();
+        applMobilesCollection = new AppleMobilesCollection(5);
+        applMobilesCollection.add(new Mobile("AM1", "Iphone X", 15, 30000));
+        applMobilesCollection.add(new Mobile("AM2", "Iphone XI", 25, 40000));
+        applMobilesCollection.add(new Mobile("AM3", "Iphone XII", 30, 55000));
+    }
+
+    @Test
+    void shouldGetTotalCostOfAppleMobilesInStore() {
+        double actualCost = mobileStore.getTotalInventoryCost(applMobilesCollection);
+        int expectedCost = 3100000;// 15 * 30000 + 25 * 40000 + 30 * 55000;
+        Assertions.assertEquals(expectedCost, actualCost);
+    }
+    @Test
+    void shouldGetTotalCostOfSamsungMobilesInStore() {
+        var samsungMobileCollection = new SamsungMobileCollection();
+        samsungMobileCollection.add(new Mobile("SAM1", "Galaxy X", 15, 20000));
+        samsungMobileCollection.add(new Mobile("SAM2", "Galaxy XI", 25, 30000));
+        samsungMobileCollection.add(new Mobile("SAM3", "Galaxy XII", 30, 45000));
+
+        double actualCost = mobileStore.getTotalInventoryCost(samsungMobileCollection);
+        int expectedCost = 2400000; // 15 * 20000 + 25 * 30000 + 30 * 45000;
+        Assertions.assertEquals(expectedCost, actualCost);
+    }
+
+}