package Chapter7;

public class StackOfIntegers {
 private int[] elements;
 private int size;
 public static final int MAX_SIZE = 16;

 /** Construct a stack with the default capacity 16 */
 public StackOfIntegers() {
 this(MAX_SIZE);
 }

 /** Construct a stack with the specified maximum capacity */
 public StackOfIntegers(int capacity) {
 elements = new int[capacity];
 }

 /** Push a new integer into the top of the stack */
 public int push(int value) {
 if (size >= elements.length) {
 int[] temp = new int[elements.length * 2];
 System.arraycopy(elements, 0, temp, 0, elements.length);
 elements = temp;
 }

 return elements[size++] = value;
 }

 /** Return and remove the top element from the stack */
 public int pop() {
 return elements[--size];
 }

 /** Return the top element from the stack */
 public int peek() {
 return elements[size - 1];
 }

 /** Test whether the stack is empty */
 public boolean empty() {
 return size == 0;
 }

 /** Return the number of elements in the stack */
 public int getSize() {
 return size;
 }
}