Eclipse中有一个bug，有时如果你创建了一个新的@+id/..，它不会立即添加到R.java文件中，即使在清理构建项目之后也是如此。解决方案是重新启动Eclipse。

我认为这个问题应该尽快解决，因为它可能(从经验来看，将会)使一些开发人员感到困惑，认为他们的语法有问题，并试图调试它，即使实际上没有什么需要调试的。

摘自开发者指南:

android:id="@+id/my_button"

The at-symbol (@) at the beginning of the string indicates that the XML parser should parse and expand the rest of the ID string and identify it as an ID resource. The plus-symbol (+) means that this is a new resource name that must be created and added to our resources (in the R.java file). There are a number of other ID resources that are offered by the Android framework. When referencing an Android resource ID, you do not need the plus-symbol, but must add the android package namespace, like so:

android：id=“@android：id/empty”

+号是将id添加到资源id列表的快捷方式。否则，您需要将它们保存在这样的xml文件中

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item name="my_logo" type="id"/>
</resources>

@id/和@android:id/不一样。

@id/引用应用程序中的ID， @android: ID /引用Android平台中的项目。

Eclipse是错误的。

Android中“@+id/”和“@id/”的区别

第一个用于创建特定ui组件的ID，另一个用于引用特定组件

The plus sign (+) before the resource type is needed only when you're defining a resource ID for the first time. When you compile the app, the SDK tools use the ID name to create a new resource ID in your project's R.java file that refers to the EditText element. With the resource ID declared once this way, other references to the ID do not need the plus sign. Using the plus sign is necessary only when specifying a new resource ID and not needed for concrete resources such as strings or layouts. See the sidebox for more information about resource objects.

来自:https://developer.android.com/training/basics/firstapp/building-ui.html