Help with string.matches() in java

[kirkulator]

I have input from the user which is the last name, sent to be set as the last name for my object in my setLasttName method.

public void setLastName(String lName) throws IllegalArgumentException {
if (lName.matches("[a-zA-z'-]")) {
this.lastName = lName; }
else {
throw new IllegalArgumentException("Invalid Input: name can"
+ "only consist of letters, hyphens, or apostrophes. ");
}

now, i am only aloud to have a-z, A-Z, hyphens, and apostrophes in the name, else i throw an exception. I have run this with putting '++' and other illegal input for lastname and it WILL NOT CATCH the exception, it continues with the program. what am i doing wrong? i have searched online forever trying to find a simple way to do this. is there an easier way that will work? Thanks so much! Last project of the quarter ^.^
-Amanda

 

[Mark44]

Use [ code ] and [ /code ] tags around your code (without the spaces) to preserve indentation. I have done this for you.

I have input from the user which is the last name, sent to be set as the last name for my object in my setLasttName method.

public void setLastName(String lName) throws IllegalArgumentException {
        if (lName.matches("[a-zA-z'-]")) {
        this.lastName = lName; }
        else {
            throw new IllegalArgumentException("Invalid Input: name can"
                    + "only consist of letters, hyphens, or apostrophes. ");
        }

now, i am only aloud to have a-z, A-Z, hyphens, and apostrophes in the name, else i throw an exception. I have run this with putting '++' and other illegal input for lastname and it WILL NOT CATCH the exception, it continues with the program. what am i doing wrong? i have searched online forever trying to find a simple way to do this. is there an easier way that will work? Thanks so much! Last project of the quarter ^.^
-Amanda

I think it might be the ' character that is causing problems. See if this makes a difference: ["a-zA-Z\'-]"

 

[Filip Larsen]

Some comments:

• Your character ranges include the range A-z. You probably meant A-Z (capital z).
• The matches method tries to match the whole string to the pattern so you would probably want to use a pattern like "[a-zA-Z'-]+" where the last + means "one or more" of the preceding pattern.
• You say that you cannot get your code to throw IllegalArgumentException? If so, perhaps you are blind-catching the exception at some point. Check with a debugger or with debug logging that you enter the second branch of the test, or write a small unit test that calls your setter directly and checks for IllegalArgumentException.

 

[kirkulator]

Thanks so much guys! The "+" at the end is what i needed. I'm not very familiar with the regex stuff. It seems every time i have a problem with code working its a dumb overlooking mistake. Also, thanks for the heads up on indentation! I apologize, I've never had to put code in this forum before. : )

 

[DeeNos]

Hello Amanda,

Thank you for reaching out for help with your program. It seems like you have the right idea with using the string.matches() method to validate the input for the last name. However, there may be an issue with your regular expression pattern.

The pattern you are using, "[a-zA-z'-]", only allows for one character to be matched. This means that if the user inputs a string of multiple characters, the pattern will not match and the exception will not be thrown. To fix this, you can use the "+" symbol after the character set to indicate that you want to match one or more characters. So your pattern should be "[a-zA-Z'-]+".

Additionally, you may want to consider using the "^" and "$" symbols at the beginning and end of your pattern to indicate that you want to match the entire string and not just a part of it.

I hope this helps with your project. Good luck with the rest of the quarter!