package
effectivejava.creatinganddestoyingobjects;
import java.util.EmptyStackException;
/**
* Eliminate obsolete references
*
*
*/
public class Item5 {
private Object[] elements;
private int size = 0;
public Item5(int initialCapacity) {
this.elements = new
Object[initialCapacity];
}
public void push(Object e) {
ensureCapacity();
elements[size++] = e;
}
public Object pop() {
if (size==0)
throw new
EmptyStackException();
Object result = elements[--size];
elements[size] = null; // Eliminate
obsolete reference
return result;
}
/**
* Ensure space for at least one more element, roughly
* doubling the capacity each time the array needs to grow.
*/
private void ensureCapacity() {
if (elements.length == size) {
Object[]
oldElements = elements;
elements =
new Object[2 * elements.length + 1];
System.arraycopy(oldElements, 0, elements, 0, size);
}
}
public static void main(String[] args) {
Item5 s = new Item5(0);
for (int i=0; i<args.length; i++)
s.push(args[i]);
for (int i=0;
i<args.length; i++)
System.out.println(s.pop());
}
}