Class AlternationTest

java.lang.Object

AlternationTest

public class AlternationTest
extends Object

Constructor Summary

Constructors

Constructor	Description
AlternationTest()

Method Summary

Modifier and Type	Method	Description
void	testAndRegex()	The and expression regex:
void	testIfGroupMatchRegex()	The named conditional expression regex:
void	testIfMatchRegex()	The conditional expression regex:
void	testOrRegex()	The or expression regex:

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AlternationTest

public AlternationTest()

Method Detail

testAndRegex

public void testAndRegex()

The and expression regex:

&&

In this case we execute the following regex:

[a-z&&[aeiou]]

With this regex it is expected to obtain all the vowels of a String.

testOrRegex

public void testOrRegex()

The or expression regex:

|

In this case we execute the following regex:

\d|\s

With this regex it is expected to obtain all the digits and all the white spaces.

testIfMatchRegex

public void testIfMatchRegex()

The conditional expression regex:

(?(expression)then|else)

It matches the "expression" and if the expression is matched it applies the "then" expression and if the "expression" isn't matched it applies the "else" expression.

In the test example we have the following expression:

(?(A)A\d{2}\b|\b\d{3}\b)

expression: A

then: A\d{2}\b

else: \b\d{3}\b

This means that this expression will either match an 'A' followed by two digits and a boundary or three digits between boundaries.

testIfGroupMatchRegex

public void testIfGroupMatchRegex()

The named conditional expression regex:

(?(name)then|else)

It matches the named capturing group with the name "name", applying the "then" expression if a match occurs or

the "else" expression if it doesn't.

In this test example we have the following expression:

(?<quoted>")?(?(quoted).+?"|\S+\s)

Named capturing group: (?<quoted>")?

name: quoted

then: .+?"

else: \S+\s

There are two distinct aspects, first we define the named capturing group with (?<quoted>")? and then we use the named conditional expression with (?(quoted).+?"|\S+\s). In the test example the expression asserts if the "quoted" capturing group occurs and if it does it matches any String until a '"' char, i.e. the "then" expression, otherwise it matches the remaining text, i.e. the "else" expression.