chapter 20 Exercise 22 + 21

Author: HarryDulaney

ch_19/Exercise19_01.java

@@ -0,0 +1,97 @@
+package ch_19;
+
+import java.util.Arrays;
+
+
+/**
+ * 19.1 (Revising Listing 19.1) Revise the ArrayListGenericStack class in Listing 19.1 to implement
+ * it using an array rather than an ArrayList. You should check the array size
+ * before adding a new element to the stack. If the array is full, create a new array that
+ * doubles the current array size and copy the elements from the current array to the
+ * new array.
+ */
+public class Exercise19_01 {
+    //Test
+    public static void main(String[] args) {
+        GenericStack<String> stack1 = new GenericStack<>();
+        stack1.push("Atlanta");
+        stack1.push("Memphis");
+        stack1.push("New York");
+        stack1.push("Columbus");
+        stack1.push("Chicago");
+        stack1.push("St. Louis");
+        stack1.push("New Orleans");
+        stack1.push("Boston");
+        stack1.push("Atlanta");
+        stack1.push("Memphis");
+        stack1.push("New York");
+        stack1.push("Chicago");
+        stack1.push("St. Louis");
+        stack1.push("New Orleans");
+        stack1.push("Boston");
+        stack1.push("Atlanta");
+        stack1.push("Memphis");
+        stack1.push("New York");
+        stack1.push("Columbus");
+        stack1.push("Chicago");
+        stack1.push("St. Louis");
+        stack1.push("New Orleans");
+        stack1.push("Boston");
+
+        while (stack1.getSize() > 0) {
+            System.out.println("Pop: " + stack1.pop());
+        }
+
+    }
+}
+
+class GenericStack<E> {
+    private static int capacity = 16;
+    private static final int INCREMENT = 16;
+    private int size;
+    private E[] list = (E[]) new Object[capacity];
+
+    public GenericStack() {
+    }
+
+    private void increaseCapacity() {
+        capacity += INCREMENT;
+        E[] nuList = (E[]) new Object[capacity];
+        for (int i = 0; i < list.length; i++) {
+            nuList[i] = list[i];
+        }
+        list = nuList;
+    }
+
+    public int getSize() {
+        return size;
+    }
+
+    public E peek() {
+        return list[size - 1];
+    }
+
+    public void push(E o) {
+        list[size++] = o;
+        if (size == capacity) {
+            increaseCapacity();
+        }
+    }
+
+    public E pop() {
+        if (size > 0) {
+            return list[--size];
+        } else {
+            return null;
+        }
+    }
+
+    public boolean isEmpty() {
+        return size == 0;
+    }
+
+    @Override
+    public String toString() {
+        return "stack: " + Arrays.toString(list);
+    }
+}

ch_19/exercise19_02/Exercise19_02.java renamed to ch_19/Exercise19_02.java

@@ -1,4 +1,4 @@
-package ch_19.exercise19_02;
+package ch_19;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -30,3 +30,41 @@ public static void main(String[] args) {
 }
 
 
+/**
+ * UML Diagram:
+ *
+ * <img src="../../resources/uml-diagrams/exercise19_02.png"/>
+ *
+ * @param <E> Type held by the ArrayListGenericStack instance.
+ */
+class ArrayListGenericStack<E> extends ArrayList<E> {
+
+    public int getSize() {
+        return size();
+    }
+
+    public E peek() {
+        return get(getSize() - 1);
+    }
+
+    public Object push(E o) {
+        add(o);
+        return o;
+    }
+
+    public Object pop() {
+        Object o = get(getSize() - 1);
+        remove(getSize() - 1);
+        return o;
+    }
+
+    public boolean isEmpty() {
+        return super.isEmpty();
+    }
+
+    @Override
+    public String toString() {
+        return "Stack: " + Arrays.toString(super.toArray());
+    }
+}
+