Java Regular Expressions

[Ramna Reddy]

Hi ranchers,
Iam new working with java regular expressions,I need reg-ex for accepting only alpha characters(A-Z a-z),and anything else should be thrown as error.

Any help,
Thanks in advance.

[Paul Sturrock]

Ok. What have you tried so far? What are the errors? Or do you not know where to start?

[Ramna Reddy]

Thank you Paul,for your quick reply ,

This is my code..

String Charmatch = "^[a-zA-Z]"; //dont know whether this is correct.
if( !(lname.matches(Charmatch))){
-----
}//

The requirement is, a text box which should allow only characters,anything else should throw error.
what I need is ,a regular expression which matches the requirement.

[Remko Strating]

Did you try the \d digit metacharacter like the code example

import java.util.regex.Pattern; 
import java.util.regex.Matcher; 
 
public class Test {
public static void main(String... args){
 
String TestStringbad = "1eqwerjk dasdf!3325345"; 
String TestStringgoed = "ddfjadsklfadsflj";
 
Pattern p = Pattern.compile("\\d"); 
Matcher m = p.matcher(TestStringbad); 
boolean  b = false; 
if (b = m.find()) { 
System.out.println("Wrong input"); 
}
  
 
 }
}

[Sri Jad]

Hi Remko and other ranchers,

I have the same requirement and i tried the following code , but still Its givig me "Wrong input" , any suggestion is very much appreciable.Thanks In Advance.

import java.util.regex.Pattern;
import java.util.regex.Matcher;
 
public class Test {
    public static void main(String args) {
        String TestStringbad = "1010";
        Pattern p = Pattern.compile("\\d");
        Matcher m = p.matcher(TestStringbad);
        boolean b = false;
        if (b = m.find()) {
            System.out.println("Wrong input");
        }
    }
}

[Sri Jad]

Even the following code giving me "Wrong input"

import java.util.regex.Pattern;
import java.util.regex.Matcher;
 
public class Test {
    public static void main(String args) {
        String TestString = "hjhjkhkj";
        Pattern p = Pattern.compile("\\d");
        Matcher m = p.matcher(TestString);
        boolean b = false;
        if (b = m.find()) {
            System.out.println("Wrong input");
        }
    }
}

[Sri Jad]

Even the following code giving me "Wrong input"

import java.util.regex.Pattern;
import java.util.regex.Matcher;
 
public class Test {
    public static void main(String args) {
        String TestString = "hjhjkhkj";
        Pattern p = Pattern.compile("\\d");
        Matcher m = p.matcher(TestString);
        boolean b = false;
        if (b = m.find()) {
            System.out.println("Wrong input");
        }
    }
}

[Ulf Dittmer]

For just alpha characters, try "^\\p{L}*$".

[Sri Jad]

This code works and gives following results

true:
false:
false:
false:

import java.util.regex.Pattern;
public class UtilsTest {
    public static void main(String[] args) {
        UtilsTest ut = new UtilsTest();
        ut.isNumber("123456");
        ut.isNumber("12test");
        ut.isNumber("testit");
        ut.isNumber("test12");        
}

private void isNumber(String value) {
if (((Pattern.compile("(\\d+?)").matcher(value).matches()))) {
System.out.println("true:");
} else {
System.out.println("false:");
}
}
}

[Sri Jad]

import java.util.regex.Pattern;
public class UtilsTest {
public static void main(String[] args) {
UtilsTest ut = new UtilsTest();
ut.isNumber("123456");
ut.isNumber("12test");
ut.isNumber("testit");
ut.isNumber("test12");
}
private void isNumber(String value) {
if (((Pattern.compile("(\\d+?)").matcher(value).matches()))) {
System.out.println("true:");
} else {
System.out.println("false:");
}
}
}

[Remko Strating]

I dont't exactly know what your problem is, but your code which doesn't compile because it should be public static void main (Sting... args).

Isn't giving the feedback "Wrong input" by me.

The pattern \d looks for a digit which is certainy not in the String
"hjhjkhkj".