While working with regular expressions, you need quantifiers to
specify the number of occurrences to match against. The 3 used
quantifiers are ?, + and *. ? means 0 or 1 occurrence + means
exactly one occurrence * means 0 or more occurrences String
patternStr = "Java?"; // last a can have zero or 1 occurrence
String patternStr = "Java+"; // last a can have one or more
occurrence String patternStr = "Java*"; // last a can have zero
or more occurrence