Java和C++版本的简单Stack程序

现在对C++学习了一段时间，把C++的特性和Java做比较有很强烈的快感:P
自己写了两个版本的Stack:

Java版本:
源代码Stack.java
package org;
public class Stack ...{
public static class Link ...{

protected Object data;

protected Link next;

public Link(Object data, Link next) ...{
this.data = data;
this.next = next;
}
}

private Link head = null;

public void push(Object data) ...{
head = new Link(data, head);
}

public Object peek() ...{
return head.data;
}

public Object pop() ...{
if (head == null)
return null;
Object o = head.data;
head = head.next;
return o;
}

} 测试代码StackTest.java
package org;
import junit.framework.TestCase;

public class StackTest extends TestCase ...{

public void test1() ...{
Stack s = new Stack();

assertEquals(null, s.pop());