[SOLVED] RegEx and the match() function

Programming Questions

siva_dashq

[SOLVED] RegEx and the match() function

in Programming Questions • 4 months ago

Hi everybody,

i'm having a trouble here with my regEx experiment.

In my program i have several button that are doing closely the same thing and they are named P1, P2, ... P5

So i thought instead of writting a specific controlEvent for each one i tried this :

void controlEvent(ControlEvent event){
String[] mp = match(event.controller().name(), "P"[1-5]);

if (mp != NULL )
{
//code
}
}

i'm having this error on the second line (String[] mp = match etc etc) :
The type of the expression must be an array type but it resolved to String.

And i can't figure out why, i believe i'm in line with the given examples in the Processing reference :

String[] = match( str, regexp)

Thanks for reading

Replies(9)

GoToLoop

Re: RegEx and the match() function

4 months ago

I dunno how to deal w/ match() either! But anyways, I've come up w/ an alternative:

void controlEvent(ControlEvent event) {
final String eventName = event.controller().name();
int i = 0;
while (i++ != 5) if ( ("P" + i).equals(eventName) ) break;
if (i > 5) {
println("It's not a valid event!");
return;
}
println("We've got a match!");
// Your code below:
}

And below's what I did as "test-drive":

void setup() {
  noLoop();
  controlEvent( new ControlEvent() );
  exit();
}

void controlEvent(ControlEvent event) {
  final String eventName = event.controller().name();
  int i = 0;

  while (i++ != 5) {
    println(i);
    if ( ("P" + i).equals(eventName) )  break;
  }

  if (i > 5) {
    println("It's not a valid event!");
    return;
  }

  println("We've got a match!");

  // Your code below:
}

class ControlEvent {
  ControlEvent controller() {
    return this;
  }

  String name() {
    return "P4";
    // return "P8";
  }
}

siva_dashq

Re: RegEx and the match() function

4 months ago

Thanks for that alternative, it works fine (as usual) !

i still don't get why this match() function aint workin, i'll figure it out later.

Thanks again GoToLoop

thomas.di..

Re: RegEx and the match() function

4 months ago

i think it is more comfortable to use the string.matches() method directly,
http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#matches%28java.lang.String%29

here a view examples

    System.out.println( "P0" .matches("(P[1-5])"   ) ); // false
    System.out.println( "P1" .matches("(P[1-5])"   ) ); // true
    System.out.println( "P2" .matches("(P[1-5])"   ) ); // true
    System.out.println( "P3" .matches("(P[1-5])"   ) ); // true
    System.out.println( "P4" .matches("(P[1-5])"   ) ); // true
    System.out.println( "P5" .matches("(P[1-5])"   ) ); // true
    System.out.println( "P11" .matches("(P[1-5])"   ) ); // false
    System.out.println( "P11" .matches("(P[1-5]{2})") ); // true
    System.out.println( "P15" .matches("(P[1-5]{2})") ); // true
    System.out.println( "P16" .matches("(P[1-5]{2})") ); // false
    System.out.println( "P611".matches("(P[1-6]{3})") ); // true

http://docs.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html

GoToLoop

Re: RegEx and the match() function

4 months ago

Oh, I didn't know how that worked!

Thx Thomas!

Anyways, here's my solution using that:

void controlEvent(ControlEvent event) {
if ( !event.controller().name().matches("P[1-5]") ) {
println("It's not a valid event!");
return;
}
println("We've got a match!");
// Your code below:
}

And my "test-drive" for it:

void setup() {
  noLoop();
  controlEvent( new ControlEvent() );
  exit();
}

void controlEvent(ControlEvent event) {
  if ( !event.controller().name().matches("P[1-5]") ) {
    println("It's not a valid event!");
    return;
  }

  println("We've got a match!");

  // Your code below:
}

class ControlEvent {
  ControlEvent controller() {
    return this;
  }

  String name() {
    return "P4";
    // return "P8";
  }
}

PhiLho

Re: RegEx and the match() function

4 months ago

To answer the original problem: "P"[1-5] is no a valid thing in Java. I think you intended to write: "P[1-5]" instead.

PhiLho

Re: RegEx and the match() function

4 months ago

I used the convenient test sketch of GoToLoop to add a functionality: you can get the button number.

import java.util.regex.*;
void setup()
{
controlEvent(new ControlEvent());
exit();
}
void controlEvent(ControlEvent event)
{
Pattern p = Pattern.compile("P([1-5])");
Matcher m = p.matcher(event.controller().name());
if (!m.matches())
{
println("It's not a valid event!");
return;
}
println("We've got a match! It is button " + m.group(1));
// Your code below:
}
class ControlEvent
{
ControlEvent controller()
{
return this;
}
String name()
{
return "P4";
// return "P8";
}
}

GoToLoop

Re: RegEx and the match() function

4 months ago

Neat exploration of Java's "secret" libraries, PhiLho.

But if it's important to know which button was selected, at my 1st example w/ while loop,

iterator i keeps the # of the matched button!

So, it's just enough to display the value of i:

void controlEvent(ControlEvent event) {
  final String eventName = event.controller().name();
  int i = 0;

  while (i++ != 5)  if ( ("P" + i).equals(eventName) )  break;

  if (i > 5) {
    println("It's not a valid event!");
    return;
  }

  println("We've got a match!\nIt's button #" + i + ".");

  // Your code below:
}

PhiLho

Re: RegEx and the match() function

4 months ago

Sure, but it is not fun, because it doesn't use regular expressions!

Actually, I just wanted to show it is possible to capture a part of the expression, it can be more complex than that.
If I indulge in a bit of self-promotion, I wrote some time ago a tutorial about these powerful but not easy to master expressions: http://phi.lho.free.fr/programming/RETutorial.en.html
Just don't forget than in Java, we must double all backslashes.

siva_dashq

Re: RegEx and the match() function

4 months ago

Wow with all of your responses and new insights, i can now say that this problem is solved !

Thanks to all of you

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