Need help with an application

[Jere Johnson]

Hello,
This java application will fill an array with randomly chosen uppercase letters of the alphabet. Program will write letters
to a file and display them. I cant seem to get the characters to show on the black output screen. I get weird little icons instead of characters. Am i doing something wrong?

package myprojects.assignment9;
import java.io.*;
import java.awt.*;
import java.awt.event.*;

class Assignment9 extends Frame {

public Assignment9() {
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
dispose();
System.exit(0);
}
});
}



public static void main  (String args[]) 
{
System.out.println("Starting Assignment 9...");
Assignment9 mainFrame = new Assignment9();
mainFrame.setSize(400, 400);
mainFrame.setTitle("Assignment 9");
mainFrame.setVisible(true);


int i=0; // index variable
char character; 


char [] alphabet = new char [26];



for (i=0; i<alphabet.length; i++){
character = (char)(Math.random()*26);
alphabet [i] = character;
System.out.println (alphabet [i]);}
}

public void makeGui () 
{
Button writeButton;

writeButton = new Button ("write to file");
//add (writeButton);
//writeButton.addActionListener(this);
}
public void actionPerformed(ActionEvent evt) 
{

//if (evt.getSource() == writeButton)
}

} // end of program 

[Joel McNary]

Your line of code:
character = (char)(Math.random()*26);
should read:
character = (char)(Math.random()*26) + 65;

Reason:
ASCII capital characters start with 65 ('A' = 65, not 'A' = 0) What you were displaying on your screen were mostly NPCs --> 0 through CTRL-Y

[Jere Johnson]

Joel,
I get an possible loss of precision error
when i put + 65 at the end of the statement
like this:
character = (char)(Math.random()*26)+65;

[Joel McNary]

Oops. Try:
character = (char)(Math.random()*26 + 65);
You have to cast the whole expression to a char, not just the Math.random()*26.

[Francis Siu]

hi Jeremiah
According to Joel given

 char upperCase = (char)((int)(Math.random()*26 )+ 65); 

It may be better.

[Layne Lund]

You also may wish to use char literals to make your intent more clear:

char upperCase = (char)((int)(Math.random()*('Z' - 'A' + 1)+ 'A');

In fact, you can also generalize this to create a handy helper method:

int random(int min, int max);

The implementation is left as the proverbial exercise for the reader. Such a function could be easily used for generating a random char as well. Or you can write an overloaded version for char.
Layne
[ April 29, 2003: Message edited by: Layne Lund ]