checking a string for illegal characters..help required....

[Paul Andrew]

Hello.

I am trying to make my program read a token from a string, and print out an error if the token contains invalid characters, ie smit4h.

I have this....

  public static void surnameValidation()// surname validation
        {
        for(int i=0; i<s.length(); i++)
        {
w=s.charAt(i);
String s5=" ";
s5="abcdefghijklmnopqrstuvwxyz-ABCDEFGHIJKLMNOPQRSTUVWXYZ";
x=s5.toCharArray();
failure=1;
 
for(int j=0; j<53; j++)
{
if (x[j]==w)
{
                failure=0;
}
            }
 
if (failure>=1)
{
System.out.println("Error Line " + count + " Invalid Surname " + s);
return;
}
 
        }
 
    }  

which seems to work, although i dont really understand how I got here.

Is there a better way to complete this??

Many Thanks


EDIT: Another item in the program is puzzling me also.

If a date string in the program is too long or short, format(dd-mm-yy)
another error is printed.

writing this

 public static void main (String[] args)
        {
            String a = "01-01-021";
                    if (a.length() != 8)
                    {
                        System.out.println ("Error");
                    }
        }
}   

works by itself,
but if i put it in the main program, as a method, it prints out all dates as errors, regardless of if they are wrong or not. Any ideas?
[ March 26, 2006: Message edited by: Paul Andrew ]

[Garrett Rowe]

You could use the static isLetter() method of character class along with a boolean varable:

boolean valid = true;
for (char e : someString.toCharArray())
{
   if (!Character.isLetter(e))
   {
      valid = false;
   }
}
 
if (!valid)
//...do something
 
else
//do something else

[ March 26, 2006: Message edited by: Garrett Rowe ]

[Paul Andrew]

I'm not using 1.5 which is needed for such loops unfortunately, (im on uni computers)

Thanks anyhow.

[Garrett Rowe]

You could just translate it into a non for-each loop.

boolean valid = true;
char[] myCharArray = someString.toCharArray();
for (int i = 0; i < myCharArray.length; i++)
{
   if (!Character.isLetter(myCharArray[i]))
   {
      valid = false;
   }
}
 
if (!valid)
//...do something
 
else
//do something else

[ March 26, 2006: Message edited by: Garrett Rowe ]

[Ernest Friedman-Hill]

Note also the important point that Garrett has used "myCharArray.length" instead of '53'. Using numbers like 53 is bad for all kinds of reasons; one reason is that figuring them out in the first place is extra work. A more important reason is that if the code ever must change, finding every instance of '53' may be hard to do. Better to use a variable containing the value, or compute the value as needed, the way it's been done here.

[Paul Andrew]

Great, thanks for the help guys, the code looks better already.
I have just one little thing to add to this, say i also had to allow commas to be classed as valid, which commands would to this.

eg.

if (!Character.isLetter(array1[i])) || ,

point noted about the variables, it was annoying to type in the letters
[ March 26, 2006: Message edited by: Paul Andrew ]

[Mahadevan Gorti SS]

You can try Regular expression (if your JDK > 1.4) like:

 
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
 
public class NameValidator {
static final Pattern[] patterns = new Pattern[2];
public static final int SURNAME=0;
public static final int NAME=1;

static{
patterns[SURNAME]=Pattern.compile("^[a-zA-Z]*");
patterns[NAME]=Pattern.compile("^[a-zA-Z, \\.]*");
}
/**
 * @param args
 */
public static void main(String[] args) {
String[] names = {"Mr. ABC xyz","Jr. Wallace","XyzPqr","x2 is bad"};
String[] surNames = {"vander val","gorti"};

System.out.println("Names testing:");
for(int i=0;i<names.length;i++){
String nm=names[i];
System.out.println(nm+"-->"+validate(NAME, nm));
}
System.out.println("\n\nSurnames testing");
for(int i=0;i<surNames.length;i++){
String nm=surNames[i];
System.out.println(nm+"-->"+validate(NAME, nm));
}
}

public static boolean validate(int type,String name){
Pattern pat=null;
switch(type){
case SURNAME : pat=patterns[SURNAME];break;
case NAME : pat=patterns[NAME];break;
default:// write error 
}

if(pat == null){
// write error 
return false;
}
Matcher matcher=pat.matcher(name);
return matcher.matches();
}
 
}
 
 
   

[ March 26, 2006: Message edited by: Mahadevan Gorti SS ]
[ March 27, 2006: Message edited by: Mahadevan Gorti SS ]

[Garrett Rowe]

Originally posted by Paul Andrew:
Great, thanks for the help guys, the code looks better already.
I have just one little thing to add to this, say i also had to allow commas to be classed as valid, which commands would to this.

eg.

if (!Character.isLetter(array1[i])) || ,

point noted about the variables, it was annoying to type in the letters

[ March 26, 2006: Message edited by: Paul Andrew ]

Or you could try:

if ((!Character.isLetter(array1[i])) && (array1[i] != ','))