List容易混淆的代码

package TestList;

import java.util.ArrayList;
import java.util.List;

class User {
	private String name = null;
	public User(String name) {
		this.name = name;
	}
	public String getName() {
		return this.name;
	}
	public void setName(String name) {
		this.name = name;
	}
}
public class TestList {
	public static void main(String[] args) {
		test01();
		
		User u1 = new User("123");
		User u2 = new User("456");
		List list = new ArrayList();
		list.add(u1);
		list.add(u2);
		u1.setName("aaa");
		u2.setName("bbb");
		
		for (int i = 0; i < list.size(); i++) {
			System.out.println(((User)list.get(i)).getName());
		}
	}

	private static void test01() {
		User u1 = new User("123");
		User u2 = new User("456");
		
		List list = new ArrayList();
		Object o1 = new Object();
		list.add(o1);
		o1 = u1;
		Object o2 = new Object();
		list.add(o2);
		o2 = u2;
		
		for (int i = 0; i < list.size(); i++) {
			System.out.println(list.get(i));
		}
	}
	
}