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Przepraszam
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Posts: 14398
Location: Poland. New York.
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 Posted: Sat, 21st Feb 2009 21:11 Post subject: need little java help |
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I suppose to write program that calculates are of circle using JOption to display input dialog boxes but I have run to some problem that I can not figure out
| Code: | import javax.swing.JOptionPane;
public class AreaBox {
public static void main(String[] args) {
// Enter area
String RadiusString = JOption.showInputDialog( "Enter radius, for example 2.0: ");
// Convert string to double
double Radius =
Double.parseDouble(RadiusString);
final double PI = 3.14;
double area = Radius * Radius * PI;
// Display Result
String output = "The area of circle with radius of" + Radius + " is " + double area;
JOptionPane.ShowMessageDialog(null, output);
}
} |
sorry but im a noob, currently taking programming I...guy gave us 6 programs to write and I'm kinda stuck on this one..JCreater says problem is somewhere in line 15 but I have no idea what seems to be the problem, I followed examples and in the book and not what
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LeoNatan
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Posts: 73193
Location: Ramat Gan, Israel 🇮🇱
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| Posted: Sat, 21st Feb 2009 21:16 Post subject: |
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| Code: | import javax.swing.JOptionPane;
public class AreaBox {
public static void main(String[] args) {
// Enter area
String RadiusString = JOption.showInputDialog( "Enter radius, for example 2.0: ");
// Convert string to double
double Radius =
Double.parseDouble(RadiusString);
final double PI = 3.14;
double area = Radius * Radius * PI;
// Display Result
String output = "The area of circle with radius of" + Radius + " is " + area;
JOptionPane.ShowMessageDialog(null, output);
}
} |
"double area" declares a double precision variable called "area". When you want to use it, you only have to use the name "area". |
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lhzr
Posts: 3902
Location: RO
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| Posted: Sat, 21st Feb 2009 21:20 Post subject: |
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also you can use Math.PI instead of declaring a constant equal to 3.14
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Przepraszam
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Posts: 14398
Location: Poland. New York.
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| Posted: Sat, 21st Feb 2009 21:31 Post subject: |
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iNatan, that code does not work, now I get errors in line 6 and line 16, so I take that whole program might be fucked up
haha lhzr, gonna take it slow, just learning basics for now ;p but it looks like i cant even get basics right
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LeoNatan
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Posts: 73193
Location: Ramat Gan, Israel 🇮🇱
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| Posted: Sat, 21st Feb 2009 21:53 Post subject: |
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Care to post the errors? 
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lhzr
Posts: 3902
Location: RO
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| Posted: Sat, 21st Feb 2009 22:17 Post subject: |
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at line 6, replace JOption with JOptionPane
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Przepraszam
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Posts: 14398
Location: Poland. New York.
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| Posted: Sat, 21st Feb 2009 22:17 Post subject: |
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ok, but stil get error at line 16
E:\CSCI-120\AreaBoxV2.java:16: cannot find symbol
symbol : method ShowMessageDialog(<nulltype>,java.lang.String)
location: class javax.swing.JOptionPane
JOptionPane.ShowMessageDialog(null, output);
^
1 error
Process completed.
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lhzr
Posts: 3902
Location: RO
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| Posted: Sat, 21st Feb 2009 22:19 Post subject: |
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also, if you import the javax.swing.JOptionPane package, there's no need to put JOptionPane. in front of JOptionPane members, like showInputDialog or showMessageDialog
you can write directly smth like this: String RadiusString = showInputDialog...
Last edited by lhzr on Sat, 21st Feb 2009 22:21; edited 1 time in total
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lhzr
Posts: 3902
Location: RO
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Przepraszam
VIP Member
Posts: 14398
Location: Poland. New York.
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| Posted: Sat, 21st Feb 2009 22:22 Post subject: |
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I got it
its not
| Code: | | JOptionPane.ShowMessageDialog(null, output); |
but its
| Code: | | JOptionPane.showMessageDialog(null, output); |
smaller case s instead of upper case S
thanks again, this 1400 page book gives me shivers everytime I look at it but reading is fundamental
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LeoNatan
Banned
Posts: 73193
Location: Ramat Gan, Israel 🇮🇱
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| Posted: Sun, 22nd Feb 2009 00:18 Post subject: |
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Yeah, Java uses that ugly ugly ugly naming conventions, where all methods start with a lowercase letter.
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