A validation to be developed for a JavaFX text field where single whitespace is allowed but more than one whitespace is not be allowed.
For example, "Apple Juice" -- correct "Apple Juice" -- incorrect should be restricted
if (title.matches("[a-zA-Z0-9 ]+"))
Found couple of links but not meeting my requirement. I believe that it is more of a logical tweak.
You can do:
if (title.matches([a-zA-z]+[ ][a-zA-Z]+))
[a-zA-z]+ checks for any characters before the space.[ ] checks for exactly one space.[a-zA-z]+ checks for any characters after the space.Abcd<space> or <space>Abcd, (I used <spcace> as SO does not allow two spaces to be present simultaneously) then you can replace the +s with *s., i.e.,
if (title.matches([a-zA-z]*[ ][a-zA-Z]*))
You'd better find more than a single whitespace and negate the result:
if(!title.trim().matches("\s{2,}"))
, see java.util.regex.Pattern javadoc for the syntax. The string is first trimmed, so you don't need to check for non-whitespace characters. If you don't do the trim() operation, leading and trailing whitespace will also be considered.
You could do
if ("Apple Juice".matches("\\w+ \\w+")) {
.......
