Validating a string in Java

Question

I have a question about validation in Java, I have looked at previous topic and none seem to answer my little problem.

What I am trying to do is validate what is put into a string variable in the constructor but also when a set method is used.

What I need to is If Mr Miss Mrs or Ms is entered, then to set that in a Variable (title) if not then to set title as ''Not set'' and print an error, now I know how to the the last part, its the the validation of what the user is entering into the variable I am stuck in... I have tried using an array but couldn't get it to work and tried if statements, again couldn't get it to function

Answer 1

    String title = textBoxTitle.getText();
    if(!title.equals("Mr") && !title.equals("Miss") && !title.equals("Mrs") && !title.equals("Ms"))
    {
        // Text is invalid
    }
    else
    {
        // Text is valid
    }

Answer 2

why not just call a small method that does the validation and then sets the value?

private void validateString(String) {

if string is valid 
 call setter
}

Answer 3

public void setTitle(final String title)
{
  if (title.matches("^Mrs|Mr|Miss|Ms$"))
  {
    this.title = title;
  }
  else
  {
    this.title = "Not Set";
    System.err.format("%s is not a valid title, expecting Mrs,Mr,Miss,Ms\n", title);
  }
}

if you want to do case insensitive then change the regular expression to:

"(?i)^Mrs|Mr|Miss|Ms$"

then you can just lowercase the entire thing and uppercase just the first letter to re-normalize your input to what you really want. Google for "java proper case" to find some pre-written snippets of code.

A more concise one liner, again case sensitive:

public void setTitle(final String title)
{
  title.matches("^Mrs|Mr|Miss|Ms$")) ? this.title= title: this.title= "Not Set";
}

Answer 4

i'm pretty sure u did something like --

   if(title =="Mr."){ blah.. }

   do this instead ..

   if(title.equals("Mr."){blah..}
    

Answer 5

Create a set of the words that you care about (capitalize them), and then see if the title falls into the set:

Set allowedTitles = new HashSet();
allowedTitles.add("MR");
allowedTitles.add("MRS");
allowedTitles.add("MS");
allowedTitles.add("MISS");
if (! allowedTitles.contains(textBoxTitle.getText().trim().toUpperCase()) {
   //print exception
}
else { title = textBoxTitle.getText().trim());