displaying image

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andrewtitus@alltel.net - 03 Mar 2006 02:24 GMT

The applet reads in a file and uses the file to get picture names for the
images for the applet. The program does all and compiles but I get: when I
run the program. Why is this doing this if read in file and just has to
iterate through array and get the string for the picture names.

Andy

[StBasials1.jpg, museum9.jpg, Red_Square9.jpg, StBasials8.jpg,
Russian_Soilders_in_Formation.jpg , 11-07-05_0557.jpg, 11-07-05_0727.jpg,
11-07-05_0728.jpg, 11-07-05_1010.jpg, 11-07-05_1011.jpg, 11-07-05_10111.jpg,
11-08-05_0059.jpg, 11-08-05_0100.jpg, 11-08-05_0101.jpg, 11-08-05_0412.jpg]
ÏÏ§ÏException in thread "AWT-EventQueue-1" java.lang.NullPointerException
ÏÏ§Ï    at WebApplet.paint(WebApplet.java:101)
ÏÏ§Ï    at sun.awt.RepaintArea.paintComponent(RepaintArea.java:248)
ÏÏ§Ï    at sun.awt.RepaintArea.paint(RepaintArea.java:224)
ÏÏ§Ï    at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:254)
ÏÏ§Ï    at java.awt.Component.dispatchEventImpl(Component.java:4031)
ÏÏ§Ï    at java.awt.Container.dispatchEventImpl(Container.java:2024)
ÏÏ§Ï    at java.awt.Component.dispatchEvent(Component.java:3803)
ÏÏ§Ï    at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
ÏÏ§Ï    at
java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:234)
ÏÏ§Ï    at
java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
ÏÏ§Ï    at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
ÏÏ§Ï    at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
ÏÏ§Ï    at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)

import javax.swing.JApplet;
import java.awt.Event;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.util.*;
import java.awt.*;
import javax.swing.ImageIcon;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JButton;
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
import java.net.URL.*;

public class WebApplet extends JApplet
{
private JButton previous,next;
private JPanel buttonPanel;
ArrayList names = new ArrayList();
String[] temp;
Image[] coolImage;
String url,pictureName;
Scanner fileScan, urlScan;
Font title,documentText;
int i = 0;

public void init()
{

previous = new JButton("Previous");
next = new JButton("Next");

ButtonListener listener = new ButtonListener();
previous.addActionListener(listener);
next.addActionListener(listener);
buttonPanel = new JPanel();

add(buttonPanel);

buttonPanel.add(previous);
buttonPanel.add(next);

try{
readFile();
}
catch (IOException ioex)
{
ioex.printStackTrace();
}

Image[] coolImage = new Image[names.size()];

for(int j=0; j<names.size();j++) {

coolImage[j] = getImage(getCodeBase(),(String)names.get(j));
}

} // end init()
public void readFile() throws IOException
{

fileScan = new Scanner (new File("pictures.txt"));

// Read and process each line of the file
while (fileScan.hasNext())
{

names.add(fileScan.nextLine());
}
System.out.println(names);
}

public void paint(Graphics page){

super.paint(page);
setBackground(Color.black);

title = new Font("Jokerman",Font.BOLD,(int)(getHeight()*0.02) );
documentText = new Font("Courier New",Font.BOLD,(int)(getHeight()*0.02)
);

//set color for text
page.setColor(Color.white);
page.setFont(title);

page.setFont(documentText);

page.drawImage(coolImage[i],0,30,this);

} //end paint()

private class ButtonListener implements ActionListener
{
public void actionPerformed (ActionEvent event)
{

if(event.getSource()==next) {
if(i==names.size()){

repaint();
}else
i++;
repaint();
}
if(event.getSource()==previous) {
if(i==names.indexOf(0)){

repaint();
}else
i--;
repaint();
}

}

}

} //end webApplet

Reply to this Message

andrewtitus@alltel.net - 03 Mar 2006 13:18 GMT

I added media tracker to the applet thinking that might help with the issue
Iam having but still same problem. Iam not sure what Iam doing wrong. Can
someone please point me in the right direction.

Thank You,
Andy

ERROR:
java.lang.NullPointerException
ÏÏ§Ï    at WebApplet.readFile(WebApplet.java:99)
ÏÏ§Ï    at WebApplet.init(WebApplet.java:54)
ÏÏ§Ï    at sun.applet.AppletPanel.run(AppletPanel.java:373)
ÏÏ§Ï    at java.lang.Thread.run(Thread.java:595)
import javax.swing.JApplet;
import java.awt.Event;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.util.*;
import java.awt.*;
import javax.swing.ImageIcon;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JButton;
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
import java.net.URL.*;

public class WebApplet extends JApplet implements Runnable
{
private JButton previous,next;
private JPanel buttonPanel;
String[] names;
//ArrayList names = new ArrayList();
String[] temp;
Image[] coolImage;
String url,pictureName;
Scanner fileScan, urlScan;
Font title,documentText;
int i = 0;
Thread thread;
MediaTracker tracker;

public void init()
{

tracker = new MediaTracker(this);
previous = new JButton("Previous");
next = new JButton("Next");

ButtonListener listener = new ButtonListener();
previous.addActionListener(listener);
next.addActionListener(listener);
buttonPanel = new JPanel();

add(buttonPanel);

buttonPanel.add(previous);
buttonPanel.add(next);

try{
readFile();
}
catch (IOException ioex)
{
ioex.printStackTrace();
}

Image[] coolImage = new Image[names.length];

for(int j=0; j<names.length;j++) {
coolImage[j] = getImage(getCodeBase(),names[j]);
        tracker.addImage(coolImage[j], 0);
}

} // end init()

public void start() {
thread = new Thread(this);
thread.start();
}

public void stop() {
thread.stop();
thread = null;
}

public void run() {
try {
tracker.waitForID(0);
}
catch (InterruptedException e) {
return;
}
repaint();
}

public void readFile() throws IOException
{

fileScan = new Scanner (new File("pictures.txt"));

// Read and process each line of the file
while (fileScan.hasNext())
{
int k = 0;
names[k]=fileScan.nextLine();
            k++;
}
for(int h=0;h<names.length;h++)        //trace to see if it made it here
System.out.println(names[h]);

}

public void paint(Graphics page){

super.paint(page);
setBackground(Color.black);

title = new Font("Jokerman",Font.BOLD,(int)(getHeight()*0.02) );
documentText = new Font("Courier New",Font.BOLD,(int)(getHeight()*0.02)
);

//set color for text
page.setColor(Color.white);
page.setFont(title);

page.setFont(documentText);

if ((tracker.statusID(0, true) & MediaTracker.ERRORED) != 0) {
page.setColor(Color.red);
page.fillRect(0, 0, size().width, size().height);
return;
}
if ((tracker.statusID(0, true) & MediaTracker.COMPLETE) != 0) {
for (int i = 0; i < 10; i++)
page.drawImage(coolImage[i],0,30, this);
}

} //end paint()

private class ButtonListener implements ActionListener
{
public void actionPerformed (ActionEvent event)
{

if(event.getSource()==next) {
if(i==names.length){
repaint();
}else
i++;
repaint();
}
if(event.getSource()==previous) {
if(i==0){
repaint();
}else
i--;
repaint();
}

}
}

} //end webApplet

Reply to this Message

andrewtitus@alltel.net - 03 Mar 2006 13:30 GMT

Wont display picture but makes red background where image should be. Not
sure why not getting picture.

Andy

import javax.swing.JApplet;
import java.awt.Event;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.util.*;
import java.awt.*;
import javax.swing.ImageIcon;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JButton;
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
import java.net.URL.*;

public class WebApplet extends JApplet implements Runnable
{
private JButton previous,next;
private JPanel buttonPanel;
// String[] names;
ArrayList names = new ArrayList();
String[] temp;
Image[] coolImage;
String url,pictureName;
Scanner fileScan, urlScan;
Font title,documentText;
int i = 0;
Thread thread;
MediaTracker tracker;

public void init()
{

tracker = new MediaTracker(this);
previous = new JButton("Previous");
next = new JButton("Next");

ButtonListener listener = new ButtonListener();
previous.addActionListener(listener);
next.addActionListener(listener);
buttonPanel = new JPanel();

add(buttonPanel);

buttonPanel.add(previous);
buttonPanel.add(next);

try{
readFile();
}
catch (IOException ioex)
{
ioex.printStackTrace();
}

Image[] coolImage = new Image[names.size()];

for(int j=0; j<names.size();j++) {
coolImage[j] = getImage(getCodeBase(),(String)names.get(j));
        tracker.addImage(coolImage[j], 0);
}

} // end init()

public void start() {
thread = new Thread(this);
thread.start();
}

public void stop() {
thread.stop();
thread = null;
}

public void run() {
try {
tracker.waitForID(0);
}
catch (InterruptedException e) {
return;
}
repaint();
}

public void readFile() throws IOException
{

fileScan = new Scanner (new File("pictures.txt"));

// Read and process each line of the file
while (fileScan.hasNext())
{

names.add(fileScan.nextLine());

}
        //trace to see if it made it here
System.out.println(names);

}

public void paint(Graphics page){

super.paint(page);
setBackground(Color.black);

title = new Font("Jokerman",Font.BOLD,(int)(getHeight()*0.02) );
documentText = new Font("Courier New",Font.BOLD,(int)(getHeight()*0.02)
);

//set color for text
page.setColor(Color.white);
page.setFont(title);

page.setFont(documentText);

if ((tracker.statusID(0, true) & MediaTracker.ERRORED) != 0) {
page.setColor(Color.red);
page.fillRect(0, 0, size().width, size().height);
return;
}
if ((tracker.statusID(0, true) & MediaTracker.COMPLETE) != 0) {
for (int i = 0; i < 10; i++)
page.drawImage(coolImage[i],0,30, this);
}

} //end paint()

private class ButtonListener implements ActionListener
{
public void actionPerformed (ActionEvent event)
{

if(event.getSource()==next) {
if(i==names.size()){
repaint();
}else
i++;
repaint();
}
if(event.getSource()==previous) {
if(i==0){
repaint();
}else
i--;
repaint();
}

}
}

} //end webApplet

Reply to this Message

Thomas Weidenfeller - 03 Mar 2006 14:18 GMT

> Wont display picture but makes red background where image should be. Not
> sure why not getting picture.

Use a debugger and check which data you get at which point.

> try{
> readFile();
[quoted text clipped - 3 lines]
> ioex.printStackTrace();
> }

Did you ever looked at the console? Is there maybe a stack trace? Is you
applet signed?

> public void start() {
> thread = new Thread(this);
[quoted text clipped - 15 lines]
> repaint();
> }

Consider using a Runnable instead. And Thread.stop() is deprecated for
good reasons. You probably have to remove the images from the media
tracker to ensure it will stop ASAP.

> public void readFile() throws IOException
> {
[quoted text clipped - 12 lines]
>
> }

Again: Is your applet signed?

> if ((tracker.statusID(0, true) & MediaTracker.ERRORED) != 0) {
> page.setColor(Color.red);
[quoted text clipped - 3 lines]
> if ((tracker.statusID(0, true) & MediaTracker.COMPLETE) != 0) {
> for (int i = 0; i < 10; i++)

Hard-coded number of images, while in fact you try to read them
dynamically from a file. How do you know you really got 10 images?

> private class ButtonListener implements ActionListener
> {
> public void actionPerformed (ActionEvent event)
> {
>
> if(event.getSource()==next) {

Use separate listeners. The events are initially separate. You lump them
together into one handler, just so the first thing you have to do in
this handler is to separate them again ...

> if(i==names.size()){
> repaint();

Why repaint() if apparently nothing has happened?

BTW: The usage of a global variable named 'i' is rather uncool.

> if(event.getSource()==previous) {
> if(i==0){
> repaint();

See above.

/Thomas

Signature

The comp.lang.java.gui FAQ:
ftp://ftp.cs.uu.nl/pub/NEWS.ANSWERS/computer-lang/java/gui/faq
http://www.uni-giessen.de/faq/archiv/computer-lang.java.gui.faq/

Reply to this Message

andrewtitus@alltel.net - 03 Mar 2006 14:36 GMT

I tried running a stack trace in different locations and at all points it
reads the file. I wrote this program with names of pictures hardcoded into
array names and it works not sure why this is not. This is really confusing
me. When I run the applet it flashes picture then turns red in display area.

Andy

import javax.swing.JApplet;
import java.awt.Event;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.util.*;
import java.awt.*;
import javax.swing.ImageIcon;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JButton;
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
import java.net.URL.*;

public class WebApplet extends JApplet implements Runnable
{
private JButton previous,next;
private JPanel buttonPanel;
// String[] names;
ArrayList names = new ArrayList();
String[] temp;
Image[] coolImage;
String url,pictureName;
Scanner fileScan, urlScan;
Font title,documentText;
int counter = 0;
Thread thread;
MediaTracker tracker;

public void init()
{

tracker = new MediaTracker(this);
previous = new JButton("Previous");
next = new JButton("Next");

ButtonListener listener = new ButtonListener();
previous.addActionListener(listener);
next.addActionListener(listener);
buttonPanel = new JPanel();

add(buttonPanel);

buttonPanel.add(previous);
buttonPanel.add(next);

try{
readFile();
}
catch (IOException ioex)
{
ioex.printStackTrace();
}

Image[] coolImage = new Image[names.size()];

for(int j=0; j<names.size();j++) {
coolImage[j] = getImage(getCodeBase(),(String)names.get(j));
        tracker.addImage(coolImage[j], 0);
}

} // end init()

public void start() {

thread = new Thread(this);
thread.start();
}

public void stop() {
thread.stop();
thread = null;
}

public void run() {

try {

tracker.waitForID(0);
}
catch (InterruptedException e) {
return;
}
repaint();
}

public void readFile() throws IOException
{

fileScan = new Scanner (new File("pictures.txt"));

// Read and process each line of the file
while (fileScan.hasNext())
{

names.add(fileScan.nextLine());
        // System.out.println(names);
}
}

public void paint(Graphics page){

super.paint(page);
setBackground(Color.black);

title = new Font("Jokerman",Font.BOLD,(int)(getHeight()*0.02) );
documentText = new Font("Courier New",Font.BOLD,(int)(getHeight()*0.02)
);

//set color for text
page.setColor(Color.white);
page.setFont(title);

page.setFont(documentText);

if ((tracker.statusID(0, true) & MediaTracker.ERRORED) != 0) {

page.setColor(Color.red);
page.fillRect(0, 0, size().width, size().height);
return;
}
if ((tracker.statusID(0, true) & MediaTracker.COMPLETE) != 0) {
for (int i = 0; i < names.size(); i++)
page.drawImage(coolImage[i],0,30, this);
}

} //end paint()

private class ButtonListener implements ActionListener
{
public void actionPerformed (ActionEvent event)
{

if(event.getSource()==next) {
if(counter ==names.size()){
// repaint();
}else
counter++;
repaint();
}
if(event.getSource()==previous) {
if(counter ==names.indexOf(0)){
repaint();
}else
counter--;
repaint();
}

}
}

} //end webApplet

Reply to this Message

James Westby - 03 Mar 2006 14:40 GMT

> I added media tracker to the applet thinking that might help with the issue
> Iam having but still same problem. Iam not sure what Iam doing wrong. Can
> someone please point me in the right direction.

[snip]

> public void readFile() throws IOException
> {
[quoted text clipped - 8 lines]
> k++;
> }

This loop sets k to 0 each iteration, meaning that only the first
position is ever filled. Move int k = 0 outside the loop.

[snip]

James

Reply to this Message

andrewtitus@alltel.net - 03 Mar 2006 16:48 GMT

I switched it back to an ArrayList. It reads in the names from the file and
it gets the images not sure why no display. Is there something I am missing
or is my way of thinking about the problem need adjusted.

Thank You,
Andy

import javax.swing.JApplet;
import java.awt.Event;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.util.*;
import java.awt.*;
import javax.swing.ImageIcon;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JButton;
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
import java.net.URL.*;

public class WebApplet extends JApplet implements Runnable
{
private JButton previous,next;
private JPanel buttonPanel;
// String[] names;
ArrayList names = new ArrayList();
String[] temp;
Image[] coolImage;
String url,pictureName;
Scanner fileScan, urlScan;
Font title,documentText;
int counter = 0;
Thread thread;
MediaTracker tracker;

public void init()
{

tracker = new MediaTracker(this);
previous = new JButton("Previous");
next = new JButton("Next");

ButtonListener listener = new ButtonListener();
previous.addActionListener(listener);
next.addActionListener(listener);
buttonPanel = new JPanel();

add(buttonPanel);

buttonPanel.add(previous);
buttonPanel.add(next);

try{
readFile();
}
catch (IOException ioex)
{
ioex.printStackTrace();
}

Image[] coolImage = new Image[names.size()];

for(int j=0; j<names.size();j++) {
coolImage[j] = getImage(getCodeBase(),(String)names.get(j));
tracker.addImage(coolImage[j], 0);
}

} // end init()

public void start() {

thread = new Thread(this);
thread.start();
}

public void stop() {
thread.stop();
thread = null;
}

public void run() {

try {

tracker.waitForID(0);
}
catch (InterruptedException e) {
return;
}
repaint();
}

public void readFile() throws IOException
{

fileScan = new Scanner (new File("pictures.txt"));

// Read and process each line of the file
while (fileScan.hasNext())
{

names.add(fileScan.nextLine());

}
System.out.println(names);
}

public void paint(Graphics page){

super.paint(page);
setBackground(Color.black);

title = new Font("Jokerman",Font.BOLD,(int)(getHeight()*0.02) );
documentText = new Font("Courier New",Font.BOLD,(int)(getHeight()*0.02)
);

//set color for text
page.setColor(Color.white);
page.setFont(title);

page.setFont(documentText);

if ((tracker.statusID(0, true) & MediaTracker.ERRORED) != 0) {

page.setColor(Color.red);
page.fillRect(0, 0, size().width, size().height);
return;
}
if ((tracker.statusID(0, true) & MediaTracker.COMPLETE) != 0) {
for (int i = 0; i < names.size(); i++)
page.drawImage(coolImage[i],0,30, this);
}

} //end paint()

private class ButtonListener implements ActionListener
{
public void actionPerformed (ActionEvent event)
{

if(event.getSource()==next) {
if(counter ==names.size()){
// repaint();
}else
counter++;
repaint();
}
if(event.getSource()==previous) {
if(counter ==names.indexOf(0)){
repaint();
}else
counter--;
repaint();
}

}
}

} //end webApplet

Reply to this Message

Erich Blume - 03 Mar 2006 19:24 GMT

On 3/3/06 8:48 AM, in article hZSdnc3B_5ba7pXZRVn-iQ@giganews.com,

> I switched it back to an ArrayList. It reads in the names from the file and
> it gets the images not sure why no display. Is there something I am missing
[quoted text clipped - 25 lines]
> // String[] names;
> ArrayList names = new ArrayList();

I've rarely used ArrayList, but I do know that I once ran in to a lot of
trouble with them that was solved by calling names.trim(); right after
instantiating a new ArrayList. Also, you'll want to make it an ArrayList of
String, I believe. So this is your new code, if I am right:

ArrayList<String> names = new ArrayList<String>();
names.trim();

This was because there are null occupied spaces in the ArrayList at first.
The exact reasons for that I don't know, I don't grok the ArrayList ADT.
Probably, it's because of performance issues, and initializing it to ten
spaces improves overall performance. You might want to read up on that.

There's another thing "wrong" about your code - you are way, way
over-importing things. This won't change your code at all, but it makes for
some strange reading. Change all your important statements to this:

import java.util.*;
import java.awt.*;
import javax.swing.*;
import java.io.*;
import java.net.URL.*;

The wildcard (*) will pull in all sub-elements.

Hope that helps some.

Signature

Erich Blume
e b l u m e @ u c s c dawt e d u

Libros virumque cano.

Reply to this Message

andrewtitus@alltel.net - 03 Mar 2006 19:43 GMT

I did what you said with the arry list and it cannot find name.trim().

Andy

> import java.util.*;
> import java.awt.*;
[quoted text clipped - 145 lines]
>
> } //end webApplet

Reply to this Message

Erich Blume - 03 Mar 2006 19:39 GMT

On 3/3/06 8:48 AM, in article hZSdnc3B_5ba7pXZRVn-iQ@giganews.com,

> I switched it back to an ArrayList. It reads in the names from the file and
> it gets the images not sure why no display. Is there something I am missing
> or is my way of thinking about the problem need adjusted.
>
> Thank You,
> Andy

...

> fileScan = new Scanner (new File("pictures.txt"));
>
[quoted text clipped - 7 lines]
> System.out.println(names);
> }

Wow, sorry for the double post, but that's very wrong code. I mean, it'll
compile and work, but it's not a good idea. Calling println() on anything
other than a primitive or a String calls a method on the object called
"toString()" which returns a string. ArrayList.toString(), which is what
you're calling in this line of code,

> System.out.println(names);

Will cause very very ugly output. At least, not what you want. This is what
you want. Replace the System.out line with this:

For (String line : names) System.out.println(line);

This will print out all the lines stored in names, and not the toString()
value of names.

These two posts come from the two small chunks of code I've read of your
entire post. There are likely to be additional bugs: I recommend you buy a
book on java data structures, or even just data structures in general. There
might be a reason you're using ArrayList (and it might be a good one, too),
but for now might I recommend LinkedList? A LinkedList will have more
overhead and a slower searching speed than any of array-based structures,
but it is completely growable (with no costly array-copy operations) and
rather easy to understand.

Also, the code I suggested above requires you declare your ArrayList with
generics as I suggested in my previous post - in other words, replace the
word ArrayList with ArrayList<String>. Otherwise, you'll need to modify my
code to cast the objects to Strings.

Once more, hope I've helped some.

Signature

Erich Blume
e b l u m e @ u c s c dawt e d u

Libros virumque cano.

Reply to this Message

andrewtitus@alltel.net - 03 Mar 2006 19:49 GMT

The reason I am using array list is because I did not know how many images
names would be stored in text file. I have program working when I hard code
names of pictures into arrray. but now using a text file and it seems to
read in but no disaplay. very confusing and frustrating. :)

Andy

Reply to this Message

andrewtitus@alltel.net - 03 Mar 2006 19:51 GMT

I did the trace with the for loop and it printed out valuse in array. it is
getting them to that point.

Andy

Reply to this Message

andrewtitus@alltel.net - 03 Mar 2006 21:52 GMT

I got it working. I set my images to an array list also and it worked.

Andy

Reply to this Message

displaying image

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