最初に書いたarraylistでスタック操作をシミュレート

package hashMap;
import java.util.ArrayList;
import d.Student;
/**
 *  ArrayList 
 * @author  
 * @see 2010 8 14 
 */

public class Stack
{
	ArrayList<Student> al=new ArrayList<Student>();
	public Object peek()
	{
		return al.get(0);
	}
	public Object pop()// 
	{
		return al.remove(al.size()-1);
	}
	public void push(Student o)// 
	{
		al.add(o);
	}
	public void clear()// 
	{
		al.clear();
	}
	public boolean isEmpty()// 
	{
		if(al.isEmpty())
		{
			return true;
		}
		else 
		{
			return false;
		}
	}
	public Object getIndex(int i)// 
	{
		return al.get(i);
	}
}

package hashMap;
import d.Student;
/**
 *  ArrayList 
 * @author  
 * @see 2010 8 14 
 */
public class StackTest
{
	public static void main(String[] args)
	{
		Stack s1=new Stack();
		s1.push(new Student(" ",200));
		s1.push(new Student(" ",200));
		s1.push(new Student(" ",200));
		s1.push(new Student(" ",200));
		while(!s1.isEmpty())
		{
			System.out.println(s1.pop());// 
		}
		
	}
}

package hashMap;
/**
 *  ArrayList 
 * @author  
 * @see 2010 8 14 
 */
public class Student
{
	String name;
	int age;
	public Student(String name,int age)
	{
		this.name=name;
		this.age=age;
	}
	public String toString()
	{
		return " :" +name+" :"+age;
	}
}