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Regular Expressions in a Java if statement

  • 16-04-2015 08:32AM
    #1
    veryangryman
    Registered Users, Registered Users 2 Posts: 5,755 ✭✭✭


    See below current if statement code. Im not great with regexs. Can you advise how i would reformat this to make it shorter.

    if(!(securityDefinitionName.contains("Directory")) &&
    (!(securityDefinitionName.contains("OK"))) &&
    (!(securityDefinitionName.contains("/"))) &&
    (!(securityDefinitionName.contains("default"))))


Comments

  • #2
    28064212
    Registered Users, Registered Users 2 Posts: 11,088 ✭✭✭✭28064212


    Why? What you have is a simple, efficient, readable implementation. Although you could probably get rid of some of the parentheses, just to make it slightly easier to read: 
    if(!securityDefinitionName.contains("Directory") &&
!securityDefinitionName.contains("OK") &&
!securityDefinitionName.contains("/") &&
!securityDefinitionName.contains("default"))
    Introducing regex would be highly unnecessary

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  • #3
    veryangryman
    Registered Users, Registered Users 2 Posts: 5,755 ✭✭✭veryangryman


    28064212 wrote: »
    Why? What you have is a simple, efficient, readable implementation. Although you could probably get rid of some of the parentheses, just to make it slightly easier to read: 
    if(!securityDefinitionName.contains("Directory") &&
!securityDefinitionName.contains("OK") &&
!securityDefinitionName.contains("/") &&
!securityDefinitionName.contains("default"))
    Introducing regex would be highly unnecessary

    Thanks for reply. Am using Groovy, which (because of lack of semicolon dependance) doesn't like having multiple lines. I know theres way around that too, but am trying to get a good example of how to use regexs for this (and other stuff). StackOverflow doesnt seem to have a decent example.

    Looking for something along lines of

    if(!securityDefinitionName.contains("Directory|OK|/|default")

    to fit into a one liner without needing scrollbars :)


  • #4
    28064212
    Registered Users, Registered Users 2 Posts: 11,088 ✭✭✭✭28064212


    You want the String.matches method. Off the top of my head 
    if(!securityDefinitionName.matches(".*Directory.*|.*OK.*|.*/.*|.*default.*"))

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  • #5
    lynchie
    Registered Users, Registered Users 2, Paid Member Posts: 2,032 ✭✭✭lynchie


    veryangryman wrote: »
    Thanks for reply. Am using Groovy, which (because of lack of semicolon dependance) doesn't like having multiple lines. I know theres way around that too, but am trying to get a good example of how to use regexs for this (and other stuff). StackOverflow doesnt seem to have a decent example.

    Looking for something along lines of

    if(!securityDefinitionName.contains("Directory|OK|/|default")

    to fit into a one liner without needing scrollbars :)

    Firstly - There is absolutely nothing wrong with having multiple lines in groovy. The following is across multiple lines?
    def securityDefinitionName= "test test OK"

if(!securityDefinitionName.contains("Directory") &&
!securityDefinitionName.contains("OK") &&
!securityDefinitionName.contains("/") &&
!securityDefinitionName.contains("default"))
println "Not found"
else println "found"
    Secondly if you want to use a regex with groovy the following would work
    if(!(securityDefinitionName =~ /Directory|OK|default|\//))


  • #6
    Anesthetize
    Registered Users, Registered Users 2 Posts: 1,469 ✭✭✭Anesthetize


    veryangryman wrote: »
    See below current if statement code. Im not great with regexs. Can you advise how i would reformat this to make it shorter.

    if(!(securityDefinitionName.contains("Directory")) &&
    (!(securityDefinitionName.contains("OK"))) &&
    (!(securityDefinitionName.contains("/"))) &&
    (!(securityDefinitionName.contains("default"))))
    This implementation would be stricter and more readable than a regex. If you really want to reformat it, extract the code in the if condition to a method called securityDefinitionNameIsValid and pass in securityDefinitionName as an argument.

    Something like this:
    if (securityDefinitionNameIsValid(securityDefinitionName)) {
      ....
      ....
}

....
....

private boolean securityDefinitionNameIsValid(String securityDefinitionName) {
    return !securityDefinitionName.contains("Directory") && 
        !securityDefinitionName.contains("OK") && 
        !securityDefinitionName.contains("/") && 
        !securityDefinitionName.contains("default"));
}
    Now the if statement looks far simpler and it's easier to understand what it's checking for :)


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