Re: CLI Java Glitch
On Wed, 22 Jun 2011, Nigel Wade wrote:
On 21/06/11 22:49, Tom Anderson wrote:
On Tue, 21 Jun 2011, Esmond Pitt wrote:
On 21/06/2011 8:09 AM, Martin Gregorie wrote:
The Java language system does case-sensitive comparisons between class
names and the files that contain them when checking that a class name
matches the file name that contains it
Nitpicking, but it doesn't really do that, does it. It opens a .class
file of the name the user specified, loads the class(es) it contains,
and tries to find the classname it was looking for among those
classes. It doesn't explicitly compare the filename and the classname.
The operating system gave it HelloWorld.class in response to
'helloworld.class' because that's how the OS file system happened to
work.
The way Java does this at the moment means that 'java helloworld',
where there is no class 'helloworld', does different things on Windows
depending on whether there is a class HelloWorld, hElLoWoRlD,
HelloworlD, etc.
Does it? What different thing does it do?
To clarify, i meant that it does different things in these three
situations:
(1) helloworld exists
(2) HelloWorld, hElLoWoRlD, HelloworlD, or similar exists
(3) no class case-insensitively called helloworld exists
I think that cases (2) and (3) should do the same thing. Or, as you
describe it:
Java actually throws ClassNotFoundException in all cases, on all OS,
just as it should. The only difference is that in a case-insensitive
filesystem Java actually opens the case-insensitive filename before it
discovers that it does not contain the class required. On case-sensitive
filesystems the correct case filename won't be found. The actual result
is the same in both cases, a ClassNotFoundException.
Now, this is where i think i've gone wrong. Back when i used Windows, java
did *not* do the same thing in cases (2) and (3). For the nonexistent file
in (3), it would throw a NoClassDefFoundError. But for the misnamed file
in (2), it would throw something else - a ClassFormatError, i think.
It seems that this has been fixed without me noticing, and i failed to
interpret Gene's original post correctly. If this is the case, then i
withdraw my complaint entirely!
tom
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