Attempt to include a core class (java.* or javax.*) 问题解决办法

 
    这是我第二次遇到这个错误，导致程序无法运行，两次均是在我导入外部jar包后发生的错误

2010-12-11 01:12:28 - myplayer]
trouble processing "java/net/DatagramPacket.class":
[2010-12-11 01:12:28 - myplayer]
Attempt to include a core class (java.* or javax.*) in something other
than a core library. It is likely that you have attempted to include
in an application the core library (or a part thereof) from a desktop
virtual machine. 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. 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.

[2010-12-11 01:12:28 - myplayer]1 error; aborting
[2010-12-11 01:12:28 - myplayer]Conversion to Dalvik format failed with error 1

最后的解决办法 是 修改.classpath 文件
只要使 .classpath 文件 中的path属性值为正确的jar路径即可
红色部分为我引用的外部jar包 路径，保证这些路径正确且唯一即可
<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry kind="src" path="src"/>
<classpathentry kind="src" path="gen"/>
<classpathentry kind="con"     path="com.android.ide.eclipse.adt.ANDROID_FRAMEWORK"/>
<classpathentry kind="lib" path="lib/cpdetector_1.0.7.jar"/>
<classpathentry kind="lib" path="lib/antlr.jar"/>
<classpathentry kind="lib" path="lib/chardet.jar"/>
<classpathentry kind="output" path="bin"/>
</classpath>

另外博客 http://fancyboy2050.iteye.com/blog/745059中介绍了 因为 sdk版本问题引发上述错误的解决办法，可以学习一下