TweetFollow Us on Twitter

Apr 97 Top 10

Volume Number: 13 (1997)
Issue Number: 4
Column Tag: Symantec Top Ten

Symantec Top 10

By Matthew Hopkins

In this month's column, we are focusing on customer issues pertaining to our C++ and Java development environments, including the newly released Visual Café. Let's warm up with a question regarding Visual Page, a dynamic web-authoring utility

Q: In Visual Page, how do you tell what size a document is before you save it?

A: By selecting Download Statistics... from the Edit menu, you can see a dialog box which not only tells you the total document size, but also tells you how long (on the average) it will take to download your page, depending upon the speed of your modem.

Q: I am using Visual Café, and I am having a problem getting the GridLayout to work properly. For instance, when I set the number of columns to 3 in the Property Manager, the applet doesn't respond at all visually. What's going on here?

A: Visual Café behaves in this manner because of how GridLayout is implemented in Java. When the rows and columns are both defined to anything other than 0, the Layout Manager will ignore the number of columns you have specified and calculate them based upon the number of rows and the number of elements. If you are interested in having the Layout Manager organize your elements according to a certain number of columns, set the number of rows to 0 (meaning "any"), and the Layout Manager will make the number of rows dependent upon the number of columns.

Q: I am getting an error of type -43 when running my Java application in Symantec Café. How do I correct this?

A: In an application, the main function needs to be static, and the main class needs to be set in the Project Options window.

Q: I am running the following program in Symantec Café and it does nothing but hang. Could you tell me why?

class PrintThread implements Runnable {
         String str;
         
         public PrintThread (String str) {
                 this.str = str;
         } 

         public void run() {
                 for (;;)
                         System.out.print(str);
         } 
} 

class ConcurrencyTest {
         public static void main(String argv[]) {
                 new Thread(new PrintThread("A")).start();
                 new Thread(new PrintThread("B")).start();
          } 
} 

A: This does not actually cause a freeze. It just appears that way because the System.out.print never receives a "" character, so it never shows you what's going on; it adds characters to the print stream indefinitely. To achieve the results you intended (mainly, seeing A and B printed forever), either call PrintThread with "A" and "B", or change the line reading System.out.print(str) to System.out.println(str).

Q: Which folder do you put packages into in Symantec Café for the Mac?

A: You have two options:

1) Place any additional class packages into the {java libraries} folder.

2) Place them in whatever folder you like as long as you open the Preferences:Paths window and add the search path to the upper window so that Café will know to search that folder.

Q: I am developing an application in Café that includes HTML text and embedded Applets. Some of the applets need to read local files whose names are supplied by the user, but the applet security rules prevent applets from reading local files. Is there a standard way of reading user-OK'ed local files that I am missing?

A: The names of the files have to be "fully qualified" (i.e. volume/folder/file), and there can be no non-standard characters anywhere in the path (like ƒ after folder names.) You can use something like this

FileDialog file_dialog_open;
file_dialog_open = new FileDialog(this, "Open A File", FileDialog.LOAD);

public void loadFile() {
 file_dialog_open.pack();
 file_dialog_open.show();
   if (file_dialog_open.getFile() != null) {
      currentFolder = file_dialog_open.getDirectory();
      selectedFile = new String(file_dialog_open.getFile());
      fullPath = currentFolder + "/" + selectedFile;
   } 
} 

This lets the user select a file and then pass the fully qualified path name for the file to the method that actually accesses the data.

Q: Is there a simple way to use ImageMaps for applets in Java? I need to write an applet that loads a graphic file at the proper coordinates when the mouse is moved over a certain location.

A: The key to this problem is the Component action method mouseEnter(). This works for all components, including buttons, windows, etc. In order to implement ImageMaps, I find the canvas component to work the best, being invisible. Here is a small snippet of code written in Visual Café that illustrates this

import java.awt.*;
import java.applet.*;

public class Applet1 extends Applet {    
        public void init() {
                super.init();
                setLayout(null);
                addNotify();
                resize(426,266);
                theMap = new ImageMap("myMap", 50, 50, getGraphics());
                theMap.reshape(60,31,186,150);
                add(theMap);
        } 

        public boolean handleEvent(Event event) {
                return super.handleEvent(event);
        } 
        ImageMap theMap;
} 

class ImageMap extends Canvas {
        boolean on;
        String label;
        Graphics g;
        

        ImageMap(String label, int sizex, int sizey, Graphics g) {
                this.label=label;
                this.g=g;
                resize(sizex, sizey);
        } 
        
        public void paint(Graphics g) {
                update(g);
        } 
        
        public void update(Graphics g) {
                if(on) {
                        this.g.drawString("Hello, World!", 25, 25);
                } 
        } 
        
        public boolean mouseEnter(Event evt, int x, int y) {
                on=true;
                repaint();
                return true;
        } 
} 

Here, the text Hello, World! has been substituted for the image that should be displayed. In case you wish to remove the image when the mouse is removed from the area, use the method mouseExit() in the same way.

Q: I am using a HashTable to keep track of a number of Button objects in Symantec Café, but every time I click on the button and look up the corresponding HashTable entry, it returns null.

import java.applet.*;
import java.awt.*;
import java.util.*;

public class HashTblTest extends Applet {
        Hashtable ht = new Hashtable();
        Button[] b = new Button[3];

        public void init()       {
                for (int i = 0;i < 3;i++) {
                        b[i] = new Button("Button " + i);
                        add(b[i]);
                        ht.put(b[i], new Integer(i));    
                }   
        } 
        public boolean action(Event e, Object o){
                System.out.println(ht.get(o));
                return false;
        }      
} 

What am I doing wrong?

A: The problem here is that the Button action method counter-intuitively provides as its Object parameter a STRING which is the button's name, not the button object itself. You have entered the buttons themselves into the HashTable, but the action method is looking up a string, not a button in your table. The best way to work around this is to change your action code to read: System.out.println(ht.get(e.target)); This will achieve your desired results.

Q: I have written a program in the Think Project Manager 7.0.5 that runs in the debugger, but when I try to run it in the Finder or without the debugger, the main window does not even come up. What do I need to do to get it to work?

A: This usually indicates a failure to initialize the Macintosh toolbox. Your code seems to work in the debugger because the debugger initializes the toolbox for you.

Q: I have written a program that uses two-dimensional and three-dimensional arrays. It seems to look fine but I keep getting link errors. What can I do to fix this problem?

A: It sounds like you are putting some huge arrays on the stack! Space is allocated for these arrays prior to run-time, and if your arrays are large enough, you could be causing a stack overflow that is posing some problems for the linker. There is an excellent example on how to put these arrays on the heap (allocating them at run time) in the Think Reference under Arrays Bigger than 32k.

Special thanks to Mark Baldwin, Ted Flug, Richard Hill, Steve Howard, Scott Morrison, Kevin Kenan, and Kevin Quah.

 
AAPL
$524.94
Apple Inc.
+5.93
MSFT
$40.01
Microsoft Corpora
-0.39
GOOG
$536.10
Google Inc.
-20.44

MacTech Search:
Community Search:

Software Updates via MacUpdate

VMware Fusion 6.0.3 - Run Windows apps a...
VMware Fusion allows you to create a Virtual Machine on your Mac and run Windows (including Windows 8.1) and Windows software on your Mac. Run your favorite Windows applications alongside Mac... Read more
Tweetbot 1.5.1 - Popular iOS twitter cli...
Tweetbot is a full-featured OS X Twitter client with a lot of personality. Whether it's the meticulously-crafted interface, sounds and animation, or features like multiple timelines and column views... Read more
Mac DVDRipper Pro 4.1.7 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
PDFpenPro 6.2 - Advanced PDF toolkit for...
PDFpenPro allows users to edit PDF's easily. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Create... Read more
PDFpen 6.2 - Edit and annotate PDFs with...
PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Features... Read more
Monolingual 1.5.9 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Starcraft II: Wings of Liberty 1.1.1.180...
Download the patch by launching the Starcraft II game and downloading it through the Battle.net connection within the app. Starcraft II: Wings of Liberty is a strategy game played in real-time. You... Read more
Sibelius 7.5.0 - Music notation solution...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Typinator 5.9 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more

Latest Forum Discussions

See All

Have a Special Dead Trigger 2 Easter Bas...
Have a Special Dead Trigger 2 Easter Basket Full of Goodies, Courtesy of Madfinger Games Posted by Rob Rich on April 18th, 2014 [ permalink ] Dead Trigger 2 | Read more »
Almost All of Playdek’s Library is on Sa...
Almost All of Playdek’s Library is on Sale Right Now, and You Should Check it Out Posted by Rob Rich on April 18th, 2014 [ permalink ] Playdek has released quite a few great iOS ports of board and card games over the years, and now most of them... | Read more »
Zynga Launches Brand New Farmville Exper...
Zynga Launches Brand New Farmville Experience with Farmville 2: Country Escape Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
David. Review
David. Review By Cata Modorcea on April 18th, 2014 Our Rating: :: MINIMALISTIC IN A DIFFERENT WAYUniversal App - Designed for iPhone and iPad David is a minimalistic game wrapped inside of a soothing atmosphere in which the hero... | Read more »
Eyefi Unveils New Eyefi Cloud Service Th...
Eyefi Unveils New Eyefi Cloud Service That Allows Users to Share Media Across Personal Devices Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
Tales from the Dragon Mountain: The Lair...
Tales from the Dragon Mountain: The Lair Review By Jennifer Allen on April 18th, 2014 Our Rating: :: STEADY ADVENTURINGiPad Only App - Designed for the iPad Treading a safe path, Tales from the Dragon Mountain: The Lair is a... | Read more »
Yahoo Updates Flickr App with Advanced E...
Yahoo Updates Flickr App with Advanced Editing Features and More Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
My Incredible Body - A Kid's App to...
My Incredible Body - A Kid's App to Learn about the Human Body 1.1.00 Device: iOS Universal Category: Education Price: $2.99, Version: 1.1.00 (iTunes) Description: Wouldn’t it be cool to look inside yourself and see what was going on... | Read more »
Trials Frontier Review
Trials Frontier Review By Carter Dotson on April 18th, 2014 Our Rating: :: A ROUGH LANDINGUniversal App - Designed for iPhone and iPad Trials Frontier finally brings the famed stunt racing franchise to mobile, but how much does its... | Read more »
Evernote Business Notebook by Moleskin I...
Evernote Business Notebook by Moleskin Introduced – Support Available in Evernote for iOS Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »

Price Scanner via MacPrices.net

Free HopTo 2.2 Helps Enhance Your Productivit...
The HopTo app helps you do more on your iPad by providing more and easier adaccess to files and documents. Version 2.2 adds Egnyte and HopTo’s Mac OSX File Connector. If you already have the hopTo... Read more
National Distracted Driving Awareness Month:...
As the country recognizes National Distracted Driving Awareness Month, Sprint is reminding wireless consumers to focus on driving while behind the wheel, to not text or email while driving, and to... Read more
13-inch 2.4GHz Retina MacBook Pro available f...
Abt has the 13″ 2.4GHz 128GB Retina MacBook Pro available for $1229 including free shipping. Their price is $70 off MSRP. Read more
iMacs on sale for up to $160 off MSRP this we...
Best Buy has iMacs on sale for up to $160 off MSRP for a limited time. Choose free home shipping or free instant local store pickup (if available). Prices are valid for online orders only, in-store... Read more
iPad Airs on sale this weekend for up to $100...
Best Buy has WiFi iPad Airs on sale for $50 off MSRP and WiFi + Cellular iPad Airs on sale for $100 off MSRP on their online store for a limited time, with prices now starting at $449. Choose free... Read more
Apple restocks refurbished Mac minis starting...
The Apple Store has restocked Apple Certified Refurbished Mac minis for up to $150 off the cost of new models. Apple’s one-year warranty is included with each mini, and shipping is free: - 2.5GHz Mac... Read more
Hyundai Brings Apple CarPlay To The 2015 Sona...
Hyundai Motor America has announced it will bring Apple CarPlay functionality to the 2015 Sonata. CarPlay is pitched as a smarter, safer and easier way to use iPhone in the car and gives iPhone users... Read more
Updated iPads Coming Sooner Than We Had Thoug...
MacRumors, cites KGI securities analyst Ming Chi Kuo, well-respected as an Apple product prognisticator, saying that Apple will introduce an upgraded iPad Air and iPad mini in 2014/Q3, meaning the... Read more
Toshiba Unveils New High And Low End Laptop M...
Toshiba has announced new laptop models covering both the high-end and low-end of the notebook computer spectrum. Toshiba 4K Ultra HD Laptop Toshiba’s new Satellite P55t features one of the world’s... Read more
Save up to $270 with Apple refurbished 13-inc...
The Apple Store has Apple Certified Refurbished October 2013 13″ Retina MacBook Pros available starting at $1099, with models up to $270 off MSRP. Apple’s one-year warranty is standard, and shipping... Read more

Jobs Board

*Apple* Automotive Parts Department position...
Apple Automotive is one of the fastest growing dealer…and it shows. Consider making the switch to the Apple Automotive Group today! At Apple Automotive, we Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Retail - Manager - Holyoke - Apple I...
Job Summary Keeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you’re a master of them all. In the store’s fast-paced, Read more
*Apple* Retail - Manager - Apple (United Sta...
Job SummaryKeeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you're a master of them all. In the store's fast-paced, dynamic Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.