How to write validation where String/char cant be accepted

[javaBookWorm]

[CODE=java]import java.applet.App let;
import java.awt.*; // Contains all of the classes for creating user interfaces and for painting graphics and images.
import java.awt.event. *;//The root event class for all AWT events.
import java.lang.Objec t;
import java.util.Event Object;
import javax.swing.*;//Provides a set of "lightweigh t" (all-Java language) components that, to the maximum degree possible, work the same on all platforms.


public class AirlineApplet extends JApplet implements ActionListener {
JButton printPass;
JTextArea outputArea;
String output;
int seatType, seatNum, choice;
boolean[] seatArray = {false, false, false, false, false, false, false, false, false, false};

public void init() {

Container container = getContentPane( );
container.setLa yout(new FlowLayout());

chooseType();

printPass = new JButton ("Click to print boarding pass");
printPass.addAc tionListener(th is);

outputArea = new JTextArea(40, 40);

container.add(p rintPass);
container.add(o utputArea);

}


public void chooseType() {
seatType = Integer.parseIn t(JOptionPane.s howInputDialog( "Please type 1 first smoking area or 2 for non-smoking area"));
selectSeat(seat Type);
}


//
public void actionPerformed (ActionEvent event) {
outputArea.appe nd(output);

chooseType();
}

public void selectSeat(int z) {

//argument selects between the smoking and the non-smoking seat

if (z== 1)
{
if (seatArray[0] && seatArray[1] && seatArray[2] && seatArray[3] && seatArray[4])
{
choice = Integer.parseIn t(JOptionPane.s howInputDialog( "All smoking section seat has been booked. Would you like non-smoking section? 1 for Yes, 2 for No."));
if (choice == 1)
selectSeat(2);
else
JOptionPane.sho wMessageDialog( null, "Thank you,Please Come Again.");
}
else
{
//do smoking seat and make sure that the seat is set to seat unoccupied
seatNum = (int)(Math.rand om()*5);

if (!seatArray[seatNum])
seatArray[seatNum] = true;
else
selectSeat(z);

output = "You have seat " + seatNum + " smoking area. \n";
}

}
else
{
if (z== 2)
if (seatArray[5] && seatArray[6] && seatArray[7] && seatArray[8] && seatArray[9])
JOptionPane.sho wMessageDialog( null, "There are no seats available in non-smoking area. Sorry.");
else
{
//do non smoking seat and make sure that the seat is seat to unoccupied
seatNum = (5 + (int)(Math.rand om()*5));

if (!seatArray[seatNum])
seatArray[seatNum] = true;
else
selectSeat(z);




output = "You have seat " + seatNum + " in non-smoking area. \n";
}
}

}
}[/CODE]


I wanna ask how am i able to do the validation when the message box out asking the user what type of seats they want, when user key in other character than a number it should display a message to user that Char are not accepted only number accepted. Anyone can show me the code, i would appreciate.Than k

Joseph

[r035198x]

import java.applet.App let;
import java.awt.*; // Contains all of the classes for creating user interfaces and for painting graphics and images.
import java.awt.event. *;//The root event class for all AWT events.
import java.lang.Objec t;
import java.util.Event Object;
import javax.swing.*;//Provides a set of "lightweigh t" (all-Java language) components that, to the maximum degree possible, work the same on all platforms.


public class AirlineApplet extends JApplet implements ActionListener {
JButton printPass;
JTextArea outputArea;
String output;
int seatType, seatNum, choice;
boolean[] seatArray = {false, false, false, false, false, false, false, false, false, false};

public void init() {

Container container = getContentPane( );
container.setLa yout(new FlowLayout());

chooseType();

printPass = new JButton ("Click to print boarding pass");
printPass.addAc tionListener(th is);

outputArea = new JTextArea(40, 40);

container.add(p rintPass);
container.add(o utputArea);

}


public void chooseType() {
seatType = Integer.parseIn t(JOptionPane.s howInputDialog( "Please type 1 first smoking area or 2 for non-smoking area"));
selectSeat(seat Type);
}


//
public void actionPerformed (ActionEvent event) {
outputArea.appe nd(output);

chooseType();
}

public void selectSeat(int z) {

//argument selects between the smoking and the non-smoking seat

if (z== 1)
{
if (seatArray[0] && seatArray[1] && seatArray[2] && seatArray[3] && seatArray[4])
{
choice = Integer.parseIn t(JOptionPane.s howInputDialog( "All smoking section seat has been booked. Would you like non-smoking section? 1 for Yes, 2 for No."));
if (choice == 1)
selectSeat(2);
else
JOptionPane.sho wMessageDialog( null, "Thank you,Please Come Again.");
}
else
{
//do smoking seat and make sure that the seat is set to seat unoccupied
seatNum = (int)(Math.rand om()*5);

if (!seatArray[seatNum])
seatArray[seatNum] = true;
else
selectSeat(z);

output = "You have seat " + seatNum + " smoking area. \n";
}

}
else
{
if (z== 2)
if (seatArray[5] && seatArray[6] && seatArray[7] && seatArray[8] && seatArray[9])
JOptionPane.sho wMessageDialog( null, "There are no seats available in non-smoking area. Sorry.");
else
{
//do non smoking seat and make sure that the seat is seat to unoccupied
seatNum = (5 + (int)(Math.rand om()*5));

if (!seatArray[seatNum])
seatArray[seatNum] = true;
else
selectSeat(z);




output = "You have seat " + seatNum + " in non-smoking area. \n";
}
}

}
}


I wanna ask how am i able to do the validation when the message box out asking the user what type of seats they want, when user key in other character than a number it should display a message to user that Char are not accepted only number accepted. Anyone can show me the code, i would appreciate.Than k

Joseph

1.) Use code tags when posting code
2.) You could parse the String using Integer.parseIn t, if the String is not a number then an Exception will be thrown. Alternatively, you could use a regular expression.

[javaBookWorm]

1.) Use code tags when posting code
2.) You could parse the String using Integer.parseIn t, if the String is not a number then an Exception will be thrown. Alternatively, you could use a regular expression.

Thank you for your help, But i don't really understand what you mean by using regular expression. Would you show me the code by typing it in red words. Thank you.I really newbie to IOException packages, i don;t really know how to apply. Would be happy if you can teach me.

[Ganon11]

I wouldn't worry about regular expressions right now - using Exception handling is a lot easier. Here's a quick tutorial for using expressions.

[JosAH]

I wanna ask how am i able to do the validation when the message box out asking the user what type of seats they want, when user key in other character than a number it should display a message to user that Char are not accepted only number accepted. Anyone can show me the code, i would appreciate.Than k

Joseph

Basically when I enter "Fronobulax " your program is not supposed to accept my
input and when I enter "42", everything is supposed to be fine.

Have a look at the Integer.parseIn t(String s) method. It throws a particular
exception, a NumberFormatExc eption when the input doesn't make sense as a
number. Otherwise it simply returns the number represented by the String it was
fed.

A bit of try { ... } catch { ... } logic would do the rest; I'd prefer a little separate class
for this functionality but that's just me; feel free to ignore that.

kind regards,

Jos

[javaBookWorm]

Basically when I enter "Fronobulax " your program is not supposed to accept my
input and when I enter "42", everything is supposed to be fine.

Have a look at the Integer.parseIn t(String s) method. It throws a particular
exception, a NumberFormatExc eption when the input doesn't make sense as a
number. Otherwise it simply returns the number represented by the String it was
fed.

A bit of try { ... } catch { ... } logic would do the rest; I'd prefer a little separate class
for this functionality but that's just me; feel free to ignore that.

kind regards,

Jos

Dear Chief Editors,
Would you show me some examples, how can i write the code. Because i am self-learning the Java language.i know about IOException but i don't know how to use it.

[JosAH]

Dear Chief Editors,
Would you show me some examples, how can i write the code. Because i am self-learning the Java language.i know about IOException but i don't know how to use it.

Suppose you have a String 's' and you want to convert it to an integer; you don't
know whether the content of 's' makes sense as an int number; you could do this:

[code=java]
public int asInteger(Strin g s) {
try {
return Integer.parseIn t(s); // hope for the best
}
catch (NumberFormatEx ception nfe) {
// 's' wasn't a representation of a number
}
}
[/code]

kind regards,

Jos

[javaBookWorm]

Suppose you have a String 's' and you want to convert it to an integer; you don't
know whether the content of 's' makes sense as an int number; you could do this:

[code=java]
public int asInteger(Strin g s) {
try {
return Integer.parseIn t(s); // hope for the best
}
catch (NumberFormatEx ception nfe) {
// 's' wasn't a representation of a number
}
}
[/code]

kind regards,

Jos

Jos,
In my code where should i write this coding. Anyway my friend thought me something, before i asked the user to select the type of seats, an if statements was used. The if statement is like first i check whether the user key in an number or not if is not a number then error message out. But this manner was not really good.

Would you be able to write the parse.Int(S) code for me, i mean where should i write such thing in my coding. Would you write it in my coding, so at least i get an picture of what it mean.

Also, what happen if i wan to use throw and catch method, how to write it in my coding.can u write it in it and show me.

I am sorry that i too demanding, cause i really want to master my Java. thank you Josh..

Best Regard
Junior Java Programmer

[javaBookWorm]

I wouldn't worry about regular expressions right now - using Exception handling is a lot easier. Here's a quick tutorial for using expressions.

Gannon11,
I look at the tutorial, i only can understand 40% out of it. When it come to my coding i don;t really know how to apply it. can you show me your ways in writting the throw and catch exception in my code, so i am able to get that picture of how it is used.

[JosAH]

You have to write that little snippet in your 'chooseType' method; that's the place
where you want the user to type a 1 or a 2. You obtain a String value from the
option dialog you're using, so maybe an additional do ... while(<not correct>);
thingie might be of help as well.

kind regards,

Jos

[javaBookWorm]

You have to write that little snippet in your 'chooseType' method; that's the place
where you want the user to type a 1 or a 2. You obtain a String value from the
option dialog you're using, so maybe an additional do ... while(<not correct>);
thingie might be of help as well.

kind regards,

Jos

Thank Jos for your help. The snippet is the one you send to me earlier one right. Hehe. I think i know what to do. In the do while statement, i will write it as when user key in 1 then selectSeat(seat Type); to allow the user to select the seats when the integer is true. Where else the while statements will give an errors message. Hehe


I really wanna thank for all your patient in teaching me to a good students in Java.Thank you

Joseph

[javaBookWorm]

Thank Jos for your help. The snippet is the one you send to me earlier one right. Hehe. I think i know what to do. In the do while statement, i will write it as when user key in 1 then selectSeat(seat Type); to allow the user to select the seats when the integer is true. Where else the while statements will give an errors message. Hehe


I really wanna thank for all your patient in teaching me to a good students in Java.Thank you

Joseph

I try to type like that

public void chooseType asInteger (String s) {

}
when i compile it,it say that an error occur where there is no (

what it mean..and how to correct it

[JosAH]

TI really wanna thank for all your patient in teaching me to a good students in Java.Thank you

Joseph

I guess that you can manage from here; and you're welcome of course. Think of
methods as little tools. You supply them with the information they need and they
return the value that you want. If you can't describe such a method in detail in just
one or a few sentences you can be sure that your method will be too complicated.
You need to 'decompose' your method in to small methods then until you can
describe each little method in detail in just at most a few sentences.

There's nothing magic about it: it's just an old rule of thumb already known in the
age of structured programming.

Your method should contain a while or do ... while loop, catch the optional exception
that's thrown by the Integer.parseIn t() method. If an exception was thrown the
user certainly goofed so try again; otherwise return the parsed integer value.

kind regards,

Jos