Question

Check the regex classes used to process regular expressions:

Matcher

Matching

Pattern

MatchPattern

Answer 1

The Regex classes used to process regular expressions were Matcher and Pattern.

Pattern Class:

Pattern class is used to define regular expressions. You can get the obect of this pattern class by
invoking compile() method which will return Pattern object.

This Pattern object allows you to create a Matcher object of a given string.

Matcher Class:

Matcher object allows you to do reqex operations on a string. To get the Matcher object you need to
invoke matcher() of Pattern class.

For Example Lets consider a string "abcdb12".

Suppose if we need to find the last 2 letters of the given string are digits then we need to create a pattern

The pattern for this should be \d{2}$ which says \d as digit from [0-9] and {} means number of occurences
an operator must match and in this case its 2 and $ means matches end of the line.

Pattern p=Pattern.compile("\\d{2}$");

Pattern obect was created and we need to pass the string "abcdb12" to the matcher as below.

Matcher m= p.matcher("abcdb12");

So the matcher and the pattern objects were created and you need to used find() method
from matcher class to verify whether last two letters were digits in the given string.

if(m.find())
{
return true;
}
else
return false;

So if its finds then this block will return true or else it will return false. In our current example it will
return true as last two letters 1,2 were digits.