Head First Java Chapter 14 problem

[Michael Hall]

I am having a problem getting the QuizCardPlayer program in Chapter 14 of the Head First Java Book to display the question that is reading from a file written out by QuizCardBuilder. I know the question is being read in and loaded into the ArrayList but it is not getting to the JTextArea. I have removed non related code. The example code below isolates the problem.

import java.awt.*;
public class JTextAreaTest{
private JTextArea display;
private JFrame frame;
public void go(){
frame=new JFrame("JTextArea Test");
JPanel mainPanel=new JPanel();
Font bigFont=new Font("sanserif",Font.BOLD,24);
display=new JTextArea("THIS IS A TEST",10,50);//I want this to display
JScrollPane qScroller=new JScrollPane(display);
qScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
qScroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
mainPanel.add(qScroller);
frame.getContentPane().add(BorderLayout.CENTER,mainPanel);
frame.setSize(400,500);
frame.setVisible(true);
}
public static void main(String[] args){
JTextAreaTest jtextareatest=new JTextAreaTest();
jtextareatest.go();
}
} 

I can't get the text to display in the JTextArea. In the book there was a
display.setText() command but I determined that it had nothing to do with that so I removed it and just tried the above. Still nothing. Could use some help - thanks....

[Shyam Prasad Murarka]

Hi Michael,

Is the JTextArea not being displayed??

Is it the JTextArea is being displayed but text does not appear in the JTextArea??

[Keith Lynn]

Try setting the width of the frame larger.

[Ernest Friedman-Hill]

You've got the JTextArea set to 50 columns wide, you've got the JScrollPane set to never show horizontal scroll bars, and you've got the JFrame 400 pixels wide. You don't do anything with the Font, so you'll get a 12-point font. Imagine that each character is 10 pixels wide; the 50-column text area is then 500 pixels wide, so there's 50 pixels that don't show on either side.

So, given that, perhaps you would like to try resizing the window to be somewhat wider, to see what happens...

[Michael Hall]

Ok I set the font and set horizontal scrollbar policy to ALWAYS and fiddled around with the size of frame and display to come up with the following

//JTextAreaTest
import javax.swing.*;
import java.awt.*;
public class JTextAreaTest{
private JTextArea display;
private JFrame frame;
public void go(){
frame=new JFrame("JTextArea Test");
JPanel mainPanel=new JPanel();
Font bigFont=new Font("sanserif",Font.BOLD,24);
display=new JTextArea("This is a Test",10,20);//changed width to 20
display.setFont(bigFont);
JScrollPane qScroller=new JScrollPane(display);
qScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
qScroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
mainPanel.add(qScroller);
frame.getContentPane().add(BorderLayout.CENTER,mainPanel);
frame.setSize(600,500);
frame.setVisible(true);
}
public static void main(String[] args){
JTextAreaTest jtextareatest=new JTextAreaTest();
jtextareatest.go();
}
}

which displays the text ok but I still don't understand the relationship between the frame size and JTextArea size that prevents it from displaying sometimes. Where can I get an education in this?
Thanks for your help - this is better than a University!

[Michael Hall]

For others who have the same problem I found that the following settings allow questions and answers of up to 30 chars to display ok.

display=new(JTextArea(10,30));
.
.
.
frame.setSize(700,500);

Found by trial & error as I said I don't understand the relationship between the Frame setSize()command and the JTextArea(int,int) constructor yet.