一個Eclipse匯入Android變紅XX的錯誤

案子在匯入後會變成紅色方型XX，
有非常多的理由。
通常我們都要在第1時間去看Console視窗裡寫些什麼錯誤訊息。


今天在匯入案子進筆電時，
發生了一個錯誤︰

[2011-10-15 14:25:00 - JeremyLiu] Dx
trouble processing "java/nio/CharBuffer.class":

Ill-advised or mistaken usage of a core class (java.* or javax.*)
when not building a core library.

This is often due to inadvertently including a core library file
in your application's project, when using an IDE (such as
Eclipse). If you are sure you're not intentionally defining a
core class, then this is the most likely explanation of what's
going on.

However, you might actually be trying to define a class in a core
namespace, the source of which you may have taken, for example,
from a non-Android virtual machine project. This will most
assuredly not work. At a minimum, it jeopardizes the
compatibility of your app with future versions of the platform.
It is also often of questionable legality.

If you really intend to build a core library -- which is only
appropriate as part of creating a full virtual machine
distribution, as opposed to compiling an application -- then use
the "--core-library" option to suppress this error message.

If you go ahead and use "--core-library" but are in fact
building an application, then be forewarned that your application
will still fail to build or run, at some point. Please be
prepared for angry customers who find, for example, that your
application ceases to function once they upgrade their operating
system. You will be to blame for this problem.

If you are legitimately using some code that happens to be in a
core package, then the easiest safe alternative you have is to
repackage that code. That is, move the classes in question into
your own package namespace. This means that they will never be in
conflict with core system classes. JarJar is a tool that may help
you in this endeavor. If you find that you cannot do this, then
that is an indication that the path you are on will ultimately
lead to pain, suffering, grief, and lamentation.

[2011-10-15 14:25:00 - JeremyLiu] Dx 1 error; aborting
[2011-10-15 14:25:00 - JeremyLiu] Conversion to Dalvik format failed with error 1

後來查了一下國外的論壇，才發現是專案在匯入Android的Jar檔時，Library Build錯位置了。

整個關鍵在於︰

 解決方式︰
Library標籤下應該會有一個android.jar(沒有放在Android2.2目錄下) ，
將其刪除，
並再將Android2.2Library匯入即可。