Package name must have at least two identifiers 解决办法

自问自答

在建android工程的时候，在给包命名的时候提示 Package name must have at least two identifiers.
Package name.包名因该设置为 "projectname.packagename"而不是"packagename"，需要在包名前加入工程名。否则出现“Package name must have at least two identifiers” 错误。我参考的实例为：
Project name: HelloWorld
Package name: com.javaeedev.android.hello
Activity name: Hello
Application name: Hello