The Pattern class defines no constructors. A pattern is created by calling the compile( ) factory method.
One of its forms is shown here:
static Pattern compile(String pattern)
pattern parameter is the regular expression.
Matcher is created by calling the matcher( ) factory method defined by Pattern. It is shown here:
Matcher matcher(CharSequence str)
str is the character sequence that the pattern will be matched against.
CharSequence is an interface that defines a read-only set of characters. It is implemented by the String class. You can pass a string to matcher( ).