ArrayList中如何对非基本类型的对象深复制的问题，它的clone都是SHALLOW COPY？

[apollo333]

例子如下：

import java.util.ArrayList;
import java.util.Date;


public class TTT {

public static void main(String[] args){
TTT t = new TTT();
t.run();
}

public void run(){
ArrayList al = new ArrayList();
al.add(new Date());
al.add(new Date());

//ArrayList shallow = new ArrayList(al);
ArrayList shallow = (ArrayList)al.clone();

for(int i=0;i<shallow.size();i++)
System.out.println("the shallow copy is " +shallow.get(i));

((Date)shallow.get(0)).setTime(0);

for(int i=0;i<shallow.size();i++)
System.out.println("the modified shallow copy is " +shallow.get(i));

for(int i=0;i<shallow.size();i++)
System.out.println("the al is " +al.get(i));
}

}


下面是运行结果：
the shallow copy is Thu Mar 17 23:04:41 GMT 2005
the shallow copy is Thu Mar 17 23:04:41 GMT 2005
the modified shallow copy is Thu Jan 01 01:00:00 GMT 1970
the modified shallow copy is Thu Mar 17 23:04:41 GMT 2005
the al is Thu Jan 01 01:00:00 GMT 1970
the al is Thu Mar 17 23:04:41 GMT 2005

可以看到对shallow的改动影响了原ARRAYLIST。这是典型的浅复制。我想实现深复制，怎么做，就是说对shallow的改动，不影响al这个。在《JAVA与模式》书里提到用Serializable的方法先串形化再取出，感觉有点复杂，还有其他的更好方法吗？

[kingfish]

shallow.set(i,((Date)al.get(i)).clone());

[fog628]

//shallow copy
ArrayList shallow = (ArrayList)al.clone();
//deep copy
for(int i = 0; i < al.size(); i++)
shallow.set(i,((Date)al.get(i)).clone());
}

[zhshdc]

Serialize一下不复杂的