更改 MIDlet 名称或供应商属性时出现 JavaME NullPointerException（Eclipse + Series 40 模拟器）
我有一个名为 Numbers 的 MIDlet 项目，我决定将其重命名为 Digits。我决定从头开始创建一个全新的项目，而不是简单地重命名它，这样我就可以拥有新的目录、包名称、.jad/.jar 名称等。一切都很顺利，我将 .java 文件复制到 /src和资源文件到/res并重新编译成功。我在这两个项目中使用了 Eclipse Helios 和诺基亚的 Series 40 第 5 版 SDK，Feature Pack 1。
现在，由于某种奇怪的原因，当 MIDlet 在模拟器中启动时，它会抛出 NullPointerException，但不是在启动时立即抛出，而是在启动屏幕（这是一个游戏）之后抛出。我根本没有接触过代码，所以我排除了代码中出现异常的可能性，因为当项目被称为 Numbers 时它工作得很好。经过一个小时的反复试验，我发现了一件奇怪的事情：如果我打开应用程序描述符并将 MIDlet name 属性从“Digits”更改为“Numbers”（旧项目名称），则一切都会运行完美，没有抛出异常。
我在所有项目文件中进行了文本搜索，并且单词“Numbers”仅出现在应用程序描述符和 .jad 文件中，并且仅在我更改 MIDlet 名称属性之后出现，否则该字符串将无处可寻（没有类名，没有变量，没有其他属性，代码和项目中都没有字符串“Numbers”）。该参考来自哪里？ Eclipse 或 Series 40 模拟器中存在错误？什么给？
I had a MIDlet project called Numbers that I decided to rename to Digits. Instead of simply renaming it, I decided to create a brand new project from scratch, so that I can have new directory, package name, .jad/.jar names, etc. Everything went fine, I copied the .java files to /src and resource files to /res and recompiled successfully. I used Eclipse Helios and Nokia's Series 40 5th Edition SDK, Feature Pack 1, for both projects.
Now, for some weird reason when the MIDlet starts in the emulator, it throws a NullPointerException, but not immediately on startup, but after a splash screen (it's a game). I haven't touched the code at all, so I rule out the possibility of an exception in the code, since it worked just fine when the project was called Numbers. After an hour of trial and error, I found a weird thing: if I open up the Application Descriptor and change the MIDlet name property from "Digits" to "Numbers" (old project name), everything runs perfectly and no exception is thrown.
I did a text search in all project files and the word "Numbers" only appears in the Application Descriptor and the .jad file, and only after I change the MIDlet name property, otherwise that string is nowhere to be found (no class names, no variables, no other properties, neither in the code nor in the project have a string "Numbers"). Where is that reference coming from? A bug in Eclipse or Series 40 emulator? What gives?
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又查了半个小时才找到。 Series 40 SDK 目录中有一个文件夹，它显然缓存了它运行的 MIDlet，并且还保留了同一 MIDlet 的旧版本。我清理了整个目录，现在项目开始正常，并使用 MIDlet Name 和 MIDlet Vendor 中的新值。要清理的目录是：
诺基亚\Devices\S40_5th_Edition_SDK_Feature_Pack_1\bin\Storage\6500500\C\DirectLoaded\
Found, after another half an hour of investigation. There's a folder in the Series 40 SDK directory that apparently caches the MIDlets it runs, and keeps older versions of the same MIDlet there too. I cleaned the entire directory and now the project starts just fine with new values in MIDlet Name and MIDlet Vendor. The directory to clean is:
Nokia\Devices\S40_5th_Edition_SDK_Feature_Pack_1\bin\Storage\6500500\C\DirectLoaded\