如何找到“已在未命名的包中定义”的Java类？

Question

I'm trying to convert a FlowLayout() UI to a GridBagLayout() UI. After a few modification and tests, I started getting a compiler error:

*classname* is already defined in unnamed package

and I decided to roll back to the FlowLayout() version--my last working version. That version compiles fine, but when I run (from the command line), my messed up GridBagLayout() is displayed.

I tried renaming the .java file, but I get the compiler error noted above. I restarted my console window and notepad, in case something was stuck in memory somewhere. That did not fix the problem.

However, I did take the FlowLayout() version to a laptop on which I hadn't compiled the GridBagLayout() changes. On that machine, it ran just fine, giving me the FlowLayout() I was expecting.

I've scanned my /java directory for *.class, deleted all the classes I found, but I still get the error. I'm running Win7 if it makes a difference. Notepad is my "IDE" and I'm running everything from the command prompt.

What do I need to look for to flush this "unnamed package"?

Answer 1

All of your files without a leading package statement. Anyway, as reported in Java docs :

Generally speaking, an unnamed package is only for small or temporary applications or when you are just beginning the development process. Otherwise, classes and interfaces belong in named packages.

Answer 2

Refer to the link posted by @esseks to understand about Java packages. I'm posting just to help you find any duplicate class definitions fast by using findstr (Windows equivalent of grep )

C:\> CD C:\path\to\java

// delete all .class files
C:\path\to\java>del /S *.class

// find all .java files with FlowLayout class definition
C:\path\to\java>findstr /S /I /N /C:"class flowlayout" *.java

// find all .java files with GridBagLayout class definition
C:\path\to\java>findstr /S /I /N /C:"class gridbaglayout" *.java

Legend:

• /S = Recurse sub-directories
• /I = Case-insensitive match
• /N = Print line numbers
• /C = String to find in the files