add CyclicArrayDeque

Author: demonolock

src/seminar1/collections/CyclicArrayDeque.java

@@ -1,64 +1,124 @@
 package seminar1.collections;
 
+import java.util.Arrays;
 import java.util.Iterator;
+import java.util.NoSuchElementException;
 
 public class CyclicArrayDeque<Item> implements IDeque<Item> {
 
+    private static final int DEFAULT_CAPACITY = 10;
     private Item[] elementData;
+    private int head;
+    private int tail;
+    private int size;
+
+    public CyclicArrayDeque() {
+        this.elementData = (Item[]) new Object[DEFAULT_CAPACITY];
+        head = tail = 0;
+        size = 0;
+    }
 
     @Override
     public void pushFront(Item item) {
-        /* TODO: implement it */
+        if (isEmpty()) {
+            elementData[head] = item;
+            size++;
+            return;
+        }
+        if (size == elementData.length)
+            grow();
+        elementData[(--head + elementData.length) % elementData.length] = item;
+        size++;
     }
 
     @Override
     public void pushBack(Item item) {
-        /* TODO: implement it */
+        if (isEmpty()) {
+            elementData[head] = item;
+            size++;
+            return;
+        }
+        if (size == elementData.length)
+            grow();
+        elementData[(++tail + elementData.length) % elementData.length] = item;
+        size++;
     }
 
     @Override
     public Item popFront() {
-        /* TODO: implement it */
-        return null;
+        if (isEmpty())
+            throw new NoSuchElementException();
+        Item item = elementData[(head++ + elementData.length) % elementData.length];
+        size--;
+        if (size * 4 < elementData.length && size != 0)
+            shrink();
+        return item;
     }
 
     @Override
     public Item popBack() {
-        /* TODO: implement it */
-        return null;
+        if (isEmpty())
+            throw new NoSuchElementException();
+        Item item = elementData[(tail-- + elementData.length) % elementData.length];
+        size--;
+        if (size * 4 < elementData.length  && size != 0)
+            shrink();
+        return item;
     }
 
     @Override
     public boolean isEmpty() {
-        /* TODO: implement it */
-        return false;
+        return size == 0;
     }
 
     @Override
     public int size() {
-        /* TODO: implement it */
-        return 0;
+        return size;
     }
 
     private void grow() {
-        /**
-         * TODO: implement it
-         * Если массив заполнился,
-         * то увеличить его размер в полтора раз
-         */
+        changeCapacity((int)(elementData.length * 1.5D));
     }
 
     private void shrink() {
-        /**
-         * TODO: implement it
-         * Если количество элементов в четыре раза меньше,
-         * то уменьшить его размер в два раза
-         */
+        changeCapacity((int)(elementData.length / 2D));
+    }
+
+    private void changeCapacity(int newCapacity) {
+        Item[] newElementData = (Item[]) new Object[newCapacity];
+        if ((head + elementData.length) % elementData.length <= (tail + elementData.length) % elementData.length) {
+            for (int i = head, j = 0; i <= tail; i++, j++)
+                newElementData[j] = elementData[i];
+        } else {
+            int j = 0;
+            for (int i = head; i < elementData.length; i++)
+                newElementData[j++] = elementData[i];
+            for (int i = 0; i <= tail; i++)
+                newElementData[j++] = elementData[i];
+        }
+        head = 0;
+        tail = head + size - 1;
+        elementData = Arrays.copyOf(newElementData, newCapacity);
     }
 
     @Override
     public Iterator<Item> iterator() {
-        /* TODO: implement it */
-        return null;
+        return new CyclicArrayDequeIterator();
+    }
+
+    private class CyclicArrayDequeIterator implements Iterator<Item> {
+
+        private int currentPosition = head;
+
+        @Override
+        public boolean hasNext() {
+            return currentPosition != tail;
+        }
+
+        @Override
+        public Item next() {
+            return elementData[(currentPosition++ + elementData.length) % elementData.length];
+        }
+
     }
 }

tests/TestDeque.java

@@ -1,8 +1,5 @@
 import java.lang.reflect.InvocationTargetException;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.NoSuchElementException;
-import java.util.Random;
+import java.util.*;
 
 import org.junit.Assert;
 import org.junit.Before;
@@ -60,8 +57,6 @@ public void test01_isEmpty() {
         Assert.assertEquals(deque.size(), 0);
     }
 
-//в тестах с Foreach одновременно тестируется итератор
-
     @Test
     public void test02_PushFront() {
         deque.pushFront(2);
@@ -133,7 +128,6 @@ public void test10_AnyPopBack() {
             deque.pushBack(randomArray[i]);
         }
         for (int i = 9; i >= 0; i--) {
-            System.out.println(randomArray[i]);
             Assert.assertEquals(randomArray[i], (int)deque.popBack());
         }
     }
@@ -145,7 +139,6 @@ public void test011_AnyPopFront() {
             deque.pushBack(randomArray[i]);
         }
         for (int i = 0; i < 10; i++) {
-            System.out.println(randomArray[i]);
             Assert.assertEquals(randomArray[i], (int)deque.popFront());
         }
     }
@@ -170,4 +163,16 @@ public void test013_FailPopBack() {
         }
     }
 
+    @Test
+    public void test014_Iterator() {
+        int[] randomArray = getRandomArray(10);
+        for (int i = 0; i < 10; i++) {
+            deque.pushBack(randomArray[i]);
+        }
+        Iterator<Integer> iterator = deque.iterator();
+        int i = 0;
+        while (iterator.hasNext())
+            Assert.assertEquals(randomArray[i++], (int)iterator.next());
+    }
+
 }