String validation

[hbutt]

hi there,
just wanted to know how to validate a string, i.e. if the string characters other than capitals A-Z then an error message will be printed to the screen. e.g.

string = "HeLLO" => ERROR!
string = "HELLO WORLD" =>WRONG!
string = "HELLOWORLD" => CORRECT!

thanx
hgsb

 

[thekobbler]

The regex package is very useful for this.

 

[hbutt]

any further help? i aint to clever with the regex

 

[kaht]

for (int i = 0; i < str.length();i++) {
   if ((str.charAt(i) < 'A') || (str.charAt(i) > 'Z')) {
      return (false);
   }
   return (true);
}

Set up that little snippet of code inside a function, or method if you are creating your own String subclass.

-kaht

 

[new2this2002]

An example of using a pattern to validate the string..

import java.io.*;

public final class RegexTestHarness {
public static void main(String[] argv){

String testString = "HeLLO";
if(testString.matches("^[A-Z]+$&quot)
System.out.println(testString + " is valid."
else
System.out.println(testString + " is invalid."

testString = "HELLO WORLD";
if(testString.matches("^[A-Z]+$&quot)
System.out.println(testString + " is valid."
else
System.out.println(testString + " is invalid."

testString = "HELLOWORLD";
if(testString.matches("^[A-Z]+$&quot)
System.out.println(testString + " is valid."
else
System.out.println(testString + " is invalid."
}
}

 

[new2this2002]

A brief explaination of the pattern used..

^[A-Z]+$

^ = Start of a string.
[A-Z] = character between A to Z
+ = 1 or more of previous expression
$ = end of string