Computing size of a text area.

That does not tell you the height of the text area.  That tells you the width.

From the documentation on FontMetrics.getHeight():

public int getHeight()

Determines the standard height of a line of text in the font described by this font metric. This standard height is the distance between the baseline of adjacent lines of text. It is computed as the sum
getLeading() + getAscent() + getDescent()

There is no guarantee that lines of text spaced at this distance must be disjoint; such lines may overlap if some characters overshoot either the standard ascent or the standard descent.

Returns: the standard height of the font.

Sasha.

I do not think you really read the question, Sasha.  The various FontMetrics methods such as getHeight() return the metrics of a single line of text, not the height of a JTextArea or JTextPane.  The text area will likely contain multiple lines of text, and without running through the line wrapping algorithms that the text component performs, you do not know how many lines.  Then there are the borders and margins that can contribute to the height of the component.

Fontaine's response looks promising.  I will check it out and post the results.

Umm, yes, you're right, sorry, I got confused (I always get confused between textfields and textareas...). Anyway, I think what fontaine suggested will work (I would have suggested that myself :-) )

Sasha.

Btw, I think if you put your string into whatever component you are using and then call preferredSize() on that component, what you will get is exactly what you want... (but I think that this is exactly what pack() takes into account...)

Sasha.

In general you can't control the size of your components by yourself. This is done by means of a LayoutManager. Even query the size of your JTextArea will be difficult because this size is set by the LayoutManager and may be valid only about the time your dialog is made visible.
So what I suggest is to set our text in your JTextArea, wrap this JTextArea in a JScrollPane and put it on the JDialog using a proper LayoutManager.

If the size of the JTextPane is large enough, no scroll bars will be drawed. The preferred size of your JTextArea will depend on the text and fonts choosen. If you choose a LayoutManager dealing with preferred sizes (as FlowLayout) the size of your JTextArea will not larger than needed.

In general the size of your dialog will depend on the LayoutManager, but it will not be larger than needed. You can setup a maximum size. If now there is too much text, scrollbars will appear !

Dear stelet,
May I friendly lead your attention to an important issue? Here in Experts-Exchange it is common practice to lock questions with an answer only if you are the first expert in the thread, or if all other comments are
evidently wrong. Otherwise it is usual to post a *comment* only. This way the questioner can later easily choose which expert helped most. Additionally, using comments only is more polite because:
               
- the question can easily be deleted if necessary
- it cannot happen that an answer is accidentally accepted
- you show that you acknowledge the work already done
- you give other experts a chance to post a better answer
                       
Please, be so kind and use the option "withdraw answer" to convert your answer to a normal comment.
                       
Thank you for listening...   (-:

Sasha.

First, read Sasha's comments.

Second, your comments about not being able to control the size of a component are not accurate.  You can always set the layout to null, and then size things as you would like.  Or better yet, just write a custom LayoutManager, since this will allow client code to modify this behavior if they so wish.

Third, your "solution" does not address the problem.  Rather it explains the basics of layout managers, which is pretty obvious.

Finally, your answer says that I can't do what I want to do, after others have posted suggestions on how to do it.  If you had addressed their solutions, and said why they will not work, that may have been reasonable, but you did not.

Well, fontaine's answer is on the right track, but something is not quite right.  

Here is the version of his code that I am working with.  It is pretty much the same, except:

1) I made the dialog modal so I can exit after the dialog is closed.  No zombie processes that way.

2) I changed the text for the text pane.

3) I added a setLocation() so the dialog does not open up under my task bar.

4) I added a show() method to dump out some information at different spots.

None of these changes should have had an effect on the sizing of the text area.  But what is interesting is that the debug code makes it work.

Here is the program:
===========================================================================
import java.awt.*;
import java.util.*;
import javax.swing.*;

public class MyDialog extends JDialog {

    public JTextArea area = null;

    public MyDialog(Frame frame) {
        super( frame, "Test", true );

        // create the text area, and make it wrap lines
        area = new JTextArea();
        area.setLineWrap(true);
        area.setWrapStyleWord(true);

        // add the text area to the dialog
        getContentPane().add(area);
    }

    public void setText(String text) {
        // display the text in the JTextArea
        area.setText(text);

        show( this, "After area.setText()" );

        // set the size of the area to the appropriate
        // width and an arbitrary height
        area.setSize(new Dimension(getSize().width, Integer.MAX_VALUE));
        show( this, "After area.setSize()" );

        // now, pack the dialog
        pack();      
        show( this, "After pack()" );

        return;
    }


    public static void main(String args[]) {
        MyDialog myDialog = new MyDialog(new JFrame());
        show( myDialog, "After constructor" );
   
        myDialog.setSize( new Dimension( 400, Integer.MAX_VALUE ) );
        show( myDialog, "After setSize()" );
       
        myDialog.setText(
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.\n\n" +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  "
        );

        myDialog.setLocation( 200, 200 );
        myDialog.setVisible(true);        
        System.exit( 0 );
    }

    static void show( MyDialog myDialog, String desc ) {
/**/
        System.out.println( "\n" + desc + ":" );
        System.out.println( "    size = " + myDialog.getSize() );
        System.out.println( "    preferredSize = " + myDialog.getPreferredSize() );
        System.out.println( "    rows = " + myDialog.area.getRows() );
        System.out.println( "    columns = " + myDialog.area.getColumns() );
/**/
    }
}
===========================================================================
If you comment out the body of the show() method (change "/**/" to "/**  /"), the program does not work.

Curiouser and curiouser.

I will let you know what I find out.

Here is a restructured program:

==================================================
import javax.swing.*;

public class TextViewer
    extends JTextArea
{
    public TextViewer() {
        setLineWrap( true );
        setWrapStyleWord( true );
        setColumns( 35 );
        setSize( getPreferredSize().width, Integer.MAX_VALUE );

        // Without this, it does not work.
        getPreferredSize();
    }

    public static void main(String args[]) {
        JDialog dialog = new JDialog( new JFrame(), "Text Viewer", true );
        TextViewer textViewer = new TextViewer();
        textViewer.setText(
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.\n\n" +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  " +
            "This is a test of sizing a text area to fit.  "
        );
        dialog.getContentPane().add( textViewer );
        dialog.pack();
        dialog.setLocation( 200, 200 );
        dialog.setVisible( true );
        System.exit( 0 );
    }
}
==================================================

Any idea what is going on?  In particular, is this behavior a fluke, or is this supposed to work this way?