Regular Expression

[the87boy]

Why do this regular expression not work:
if (str.matches("^\\d*$") || str.matches("^\\d*" + dot + "$") ||
str.matches("^\\d*" + dot + "\\d*$")) {
return true;
} else {
return false;
}

dot is a string, who looks like this:
String dot = ",";

The 1st regular expression test if it is just a number
The 2nd regular expression test if it is a number and ends with a dot
The 3rd regular exression test if it is a dot sorrunded by numbers
It's only number (can be with a dot)

Can somebody tell me, what's wrong and maybe shorten it?

 

[Jussi Piitulainen]

Why do this regular expression not work:
if (str.matches("^\\d*$") || str.matches("^\\d*" + dot + "$") ||
str.matches("^\\d*" + dot + "\\d*$")) {
return true;
} else {
return false;
}

dot is a string, who looks like this:
String dot = ",";

The 1st regular expression test if it is just a number
The 2nd regular expression test if it is a number and ends with a dot
The 3rd regular exression test if it is a dot sorrunded by numbers
It's only number (can be with a dot)

Can somebody tell me, what's wrong and maybe shorten it?

It appears to work. It matches ",14" and "3," and "," in addition to
"314" and "3,14", though. You failed to give an example of a str that
you think should match and does not, or that you think should not
match and does.

"foo|bar|baz" matches "foo" or "bar" or "baz".
"foo,?bar" matches "foobar" or "foo,bar".

The anchors are redundant with .matches().