Scott Tiger

the client just only need the browser software.

^_^ you should use this:
<%@ page contentType="text/html; charset=gb2312" %>

PS:You are chinese? hehe.

Integer i3 = 1000;
Integer i4 = 1000;
if (i3 == i4) System.out.println("same object");
if (i3.equals(i4)) System.out.println("meaningfully equal");
if (i3 != i4) System.out.println("different objects");

o/p

same object
meaningfully equal
different objects

i think you should make a mistake
the output as follows:
meaningfully equal
different objects

when 2 compare objects are reference
the sign of the "==" is used to compare their's reference is or isn't same.

i think you should hava a look at the javaapi
may be it's good for you.

Collection<?>
because of the sign of ?
we don't know the actually type
thus we can't add anything
But the argument is the type of reference
null is the instance value of reference
So we can use add(null) this method

i agree the upstairs .
check the j2se api:

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

i also think it will invoke method(Number n) this method