如何使用或不使用java正则表达式操作符

Question

Requirement:

I have to find a application called uninstaller under a directory, that directory contains few files like Uninstaller (incase of linux os ) Uninstaller.exe (in case of windows), Uninstaller.jar and Uninstaller.lax

I tried

final String pattern = "Uninstaller.*.(exe|[^lax]|[^jar])";
final FileFilter filter = new RegexFileFilter(pattern);
files = installDir.listFiles(filter);

but its returning Uninstaller.lax in case of linux!

please help me overcome the isssue.

Answer 1

If I understand correctly, you want to match all Unistaller files that end with bin , jar , or lax . In that case, use this:

"Uninstaller\.(bin|jar|lax)"

Edit :

Ah, in that case, you can just match:

"^Uninstaller(\.exe)?$"

Answer 2

When you do this:

[^lax]

You define a character class - a token that matches ANY character as long as it is not l, a, x.

So this token

(exe|[^lax]|[^jar])

means

'match exe OR match any character that is not l/a/x OR match any character that is not j/a/r'

Clearly this is not what you want :)

You only want to match Uninstaller and Uninstaller.exe . So try

Uninstaller(\\.exe)?$

(the $ means that the string must end)

In this case you don't have to explicitly say all the things you don't want to match, just the things you do.

Answer 3

如果你想要的只是Uninstaller或Uninstaller.exe ，那么你可以使用：

final String pattern = "Uninstaller(\.exe|$)";

Answer 4

尝试正则表达式

final String pattern = "Uninstaller(\\.exe)?";