Control numeric String in java

[Gillian Anderson]

Hello,
How to control Java Strings which are numeric, i.e between 00.00 and 20.00 and that does not contain alphabetic or other character (eg # abc etc). Any help on this is hihgly appreciated. This because I want to know the basics of the java programming language from the scratch. Thanks in advance.

[HardWeaR]

Hello,
With a regular expression, it is almost done "just for that."
Here is an example show the same

String ex = "([0-1][0-9]\\.[0-9][0-9])|(20\\.00)";

If you know the regular expression in java then it would be better for understanding the concept behind this. If you need information on the expression in java, then you can take any java book and can do it quit easily. Best of Luck

[Linux-Us]

Hello,
You can also do a KeyListener, when entering a character, if not a digit or period or an arrow to redirect or exhaust a character you do. You can also manage the event-related focus, then when the control loses focus, you test if the value is correct, if not you if it displays an appropriate error message and it gives you focus. Do you have knowledge about the swing concept in java? If not then I think just do the basic of it , they will be helpful for this.

[Aaliya Seth]

Hello,
Just have a look at the following.
This is just an example and not perfect for the code

"([0-9]) | ([0-1][0-9]) | ([0-1][0-9]\\.[0-9]) | ([0-1][0-9]\\.[0-9][0-9]) |
(\\.[0-9]) | (\\.[0-9][0-9]) |(20) | (20\\.00)

I do not know that this is what you want, but still you can take it if you need and use in your code if it is helpful.

[SoftWore]

Hello,
It's okay (except that it 20.0 and perhaps other cases: I have not checked that your expression was exhaustive) The "\ \." means the character '.', if you forget the double \ \ in front, what is sought is not a point but "any character". If you need you can take a tutorial on the expression in java and how to use them in the code.

[InterNetWorKed]

Hello,
If you need you can take a look at the following code, see if it helps you.

double nt = 0;
try{
    nt = Double.parseDouble(chnt.getText());
 
    if(nt <0 | | nt > 20){
        throw(new NumberFormatException());
    }
}catch(NumberFormatException e){
    / / Display in your interface with an asterisk on the field notes and an info. stating the accepted values
}