查看Eclipse中的Problems选项卡总是很有帮助的。在我的情况下，我得到了一个“android无法解决目标‘android-8’”的错误消息，使R.java无法生成。因此，我将导入的目标纠正为我在默认情况下使用的目标。属性文件，然后我执行了一个清洁通过项目->清洁，瞧!自动生成R.java !希望能有所帮助!

如果您的R.java没有生成，解决方案之一是删除名为“blabla.out.xml”的布局文件。

删除此文件后，尝试从project -> Clean菜单中清理项目。

我遇到过几次这样的问题。我发现，如果我没有通过应用程序的名称导入包R，例如，如果我的应用程序有包名称示例。然后我发现我必须导入example.test.R才能访问任何资源。

如果没有导入，那么返回的资源是默认资源，不包括我自己的资源。

也就是说，如果你发现你只是得到一个默认资源的列表，然后检查，以确保你导入application_package_name。R而不是android。

当我试图从SDK源代码构建Support4Demos时，这个问题也发生在我身上。

在修复了资源文件中的一些问题(例如，“fill_parent”重命名为“match_parent”)后，我发现问题在清单文件中:我通过试错检查了“在AndroidManifest.xml中定义一个<应用>标签”复选框，保存了更改，R.java神奇地重新出现。然后，我重新选中了该框，保存了该文件，重新生成了R.java。

我想我遇到了Eclipse的一个缺点。

我发现这发生在我与一个破碎的布局和一切爆炸。放松，这就像你第一次学习编程时犯的错误一样，你忘记了一个分号，它就会产生100个错误。许多人惊慌失措，按下所有的按钮，使事情变得更糟。

解决方案

Make sure that anything the R. links to is not broken. Fix all errors in your XML files. If anything in the ADKs are broken, R will not regenerate. If you somehow hit something and created import android.R in your activity, remove it. Run Project -> Clean. This will delete and regenerate R and BuildConfig. Make sure Project -> Build Automatically is ticked. If not, build it manually via Menu -> Project -> Build Project . Wait a few seconds for the errors to disappear. If it doesn't work, delete everything inside the /gen/ folder If it still doesn't work, try right-clicking your project -> Android Tools -> Fix Project Properties. Check your *.properties files (in the root folder of your app folder) and make sure that the links in there are not broken. Right-click your project > properties > Android. Look at the Project Build Target and Library sections on the right side of the page. Your Build Target should match the target in your AndroidManifest.xml. So if it's set to target 17 in AndroidManifest, make sure that the Target Name is Android 4.2. If your Library has an X under the reference, remove and re-add the library until there's a green tick. This might happen if you've moved a few files and folders around.

如果R不能再生怎么办

这通常发生在XML文件损坏时。

Check errors inside your XML files, mainly within the /res/ folder Common places are /layout/ and /values/, especially if you've changed one of them recently Check AndroidManifest.xml. I find that often I change a string and forget to change the string name from AndroidManifest.xml. Check that Android SDK Build-tools is installed. Window -> Android SDK Manager -> Tools -> Android SDK Build-tools Make sure when you update the Android SDK Tools, you also update the Android SDK Platform-tools and Android ADK Build-tools. Build fails silently if they don't match. If you can't find the issue, right click /gen/ -> Restore from local history... -> tick R.java -> click Restore. Even if it doesn't solve the problem, it will clear out the extra errors to make the problem easier to find.

我没有看到它列在这里，但我遇到了我的R.java被删除的问题，不能自动重建。

我在处理switch语句和字符串时遇到了这种情况。Eclipse建议我将项目的遵从性更改为1.7，这立即破坏了项目(R.java)，因为Android不能使用这种遵从性。

控制台:

[2013-03-12 17:26:33 - CrimeAtlas] Android requires compiler compliance level 5.0 or 6.0. Found '1.7' instead. Please use Android Tools > Fix Project Properties.

我通过使用“修复项目属性”修复了这个错误，然后像建议的那样查看日志。我注释掉了文件中的XML，提到用线性布局临时替换它们。当它被修复，砰，它重新出现(如果“自动构建”是打开的)。然后，如果没有任何错误，我可以将XML文件更改回来。