How check if a String contains only one specific character? Eg:
On the String square/retrofit and square/retrofit/issues I need to check if the String has more than one / character.
square/retrofit/issues need to be false because have more than one / character and square/retrofit need to be true.
The string can have numbers.
You do not need regex. Simple indexOf and lastIndexOf methods should be enough.
boolean onlyOne = s.indexOf('/') == s.lastIndexOf('/');
EDIT 1
Of course, if / does not appear in given string above will be true. So, to avoid this situation you can also check what is returned index from one of these methods.
EDIT 2
Working solution:
class Strings {
public static boolean availableOnlyOnce(String source, char c) {
if (source == null || source.isEmpty()) {
return false;
}
int indexOf = source.indexOf(c);
return (indexOf == source.lastIndexOf(c)) && indexOf != -1;
}
}
Test cases:
System.out.println(Strings.availableOnlyOnce("path", '/'));
System.out.println(Strings.availableOnlyOnce("path/path1", '/'));
System.out.println(Strings.availableOnlyOnce("path/path1/path2", '/'));
Prints:
false
true
false
Or if you'd like to use a bit more modern approach with streams:
boolean occursOnlyOnce(String stringToCheck, char charToMatch) {
return stringToCheck.chars().filter(ch -> ch == charToMatch).count() == 1;
}
Disclaimer: This is not supposed to be the most optimal approach.
A bit more optimized approach:
boolean occursOnlyOnce(String stringToCheck, char charToMatch) {
boolean isFound = false;
for (char ch : stringToCheck.toCharArray()) {
if (ch == charToMatch) {
if (!isFound) {
isFound = true;
} else {
return false; // More than once, return immediately
}
}
}
return isFound; // Not found
}
