Matches zero or one occurrence of the preceding character or group (?) java.util.regex / By javaplanet.io References
Matches one or more occurrences of the preceding character or group (+) java.util.regex / By javaplanet.io
Matches zero or more occurrences of the preceding character or group (*) java.util.regex / By javaplanet.io
Matches any single character not within the square brackets ([^abc]) java.util.regex / By javaplanet.io