Thread: Images works on an applet, but doesn't work when an applet is in a JFrame.

Hi guys,
i'm new here and i am new in java and using ECLIPSE.

So, very shortly. The problem is explained in the title.

In an applet my mini game looks like this: single Applet
As u can see, there are 4 images, witch i coded in this way (example of background image):

public URL url;
public Image bg;
 
public void init(){
...
 
try{
		url = getDocumentBase();
		}  catch(Exception e){			
		}
		bg = getImage(url, "images / bg.png"); 
// i put there spaces cuz this site auto edits image patch.
}
 
public void paint(Graphics g){
		g.fillRect(0, 0, getSize().width, getSize().height); 
		g.drawImage(bg, 0, 0, this);
                ...
                super.paint(g);
}

Everything looks just fine in an applet, as u can see in a picture above.

But when I run it in JFrame, it looks like this: Applet in JFrame (do not pay your attention in red circles)

0 images are draw, only simple colors that are set up...
I tried to use 'getCodeBase()' in getImage method instead of 'url', but then an applet w/ JFrame don't even start and errors appear.

Where is a problem? It looks like an applet in JFrame can't read where the images is, or smth like that...
My images are placed in src/images folder.

can't figure out what's wrong...

Should I use other image drawing methods?

errors appear.

Please post the full text of any error messages.

Applets require the services of an AppletContext normally provided by a browser. Unless you create an appletcontext and set it for the applet, the applet can not use any of the services provide by the appletcontext. See the API doc to see what methods are involved.

Originally Posted by Sean4u

Put a 'e.printStackTrace()' in there

ok, i did that.

My JFrame works like that: I press run (Window) on Eclipse, JFrame appears, then i click Start button, and applet shows up in the same window.

So it runs good, but when i press Start console goes red w/ errors
However i can still play the game, but there are 0 images loaded...

console looks like that:

java.lang.NullPointerException
	at java.applet.Applet.getDocumentBase(Unknown Source)
 
	at Zaidimas.Main.init(Main.java:123) // try{
			          //url = getDocumentBase(); - error on this line
	at Zaidimas.Window.GameStart(Window.java:70) // app.init(); - in init method i use getDocumentBase() method.
	at Zaidimas.Window$7.actionPerformed(Window.java:205) // GameStart(); - in this i use init() method.
 
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
	at java.awt.EventQueue.access$000(Unknown Source)
	at java.awt.EventQueue$1.run(Unknown Source)
	at java.awt.EventQueue$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$2.run(Unknown Source)
	at java.awt.EventQueue$2.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)

From that I can say, that there is something wrong w/ getDocumentBase(); in my init(); method.

I tried to comment all this:

try{
			url = getDocumentBase();
		}catch(Exception e){
			e.printStackTrace();
		}

And put getCodeBase() instead of 'url', but console still remains red of errors and an applet don't even show up:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at java.applet.Applet.getCodeBase(Unknown Source)
 
	at Zaidimas.Main.init(Main.java:128) // block = getImage(getCodeBase(), "images/block.png"); - error on this line
	at Zaidimas.Window.GameStart(Window.java:70) // app.init(); - in this method i use getCodeBase();
	at Zaidimas.Window$7.actionPerformed(Window.java:205) // GameStart(); - in this - init();
 
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
	at java.awt.EventQueue.access$000(Unknown Source)
	at java.awt.EventQueue$1.run(Unknown Source)
	at java.awt.EventQueue$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$2.run(Unknown Source)
	at java.awt.EventQueue$2.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)

So the problem is in init(); method and it looks like Eclipse (or i should say JFrame) don't understand getCodeBase() or getDocumentBase() methods.

I need to change somehow those methods, to get images on an applet in JFrame.

Any ideas?

By the way, if i run only an applet - everything works just fine...

to get images on an applet in JFrame.

Did you read post#3 about applets and browsers and appletContext?

Unless you provide the services of the appletcontext, its methods will not work.

Originally Posted by Norm

Did you read post#3 about applets and browsers and appletContext?

Unless you provide the services of the appletcontext, its methods will not work.

But i'm creating it not for the web or browsers...
That just a simple java game, that will be runnable from .jar file.

Anyway, i don't get it how i cant provide it.

I need to use this method:

HTML Code:

Applet.getAppletContext() 
          Determines this applet's context, which allows the applet to query and affect the environment in which it runs.

or what?
where i should use it? in JFrame class or in an applet class?

If you are not going to use the applet code in a browser that provides the applet stub and context, then you will need to rewrite the code so it does not extend the applet class or use any of the applet methods.

It is possible to write code for the applet context and stub and use the setStub() method to provide those services to your applet.

Ask google

An idea:
Create a class that implements AppletStub. Create an instance of your applet class and call its setStub() method passing it an instance of your class that implements AppletStub.. Put println statements in all its methods and see which are called by your applet. add code to those methods to do what they need to do.

damn, im just a rookie in programming, ur language is too good to understand for me ...

package Zaidimas;
 
import java.applet.AppletContext;
import java.applet.AppletStub;
import java.net.URL;
 
public class MyStub implements AppletStub {
	Main applet = new Main();
 
	@Override
	public void appletResize(int width, int height) {
		// TODO Auto-generated method stub
	}
	@Override
	public AppletContext getAppletContext() {
		// TODO Auto-generated method stub
		return null;
	}
	@Override
	public URL getCodeBase() {
		// TODO Auto-generated method stub
		return null;
	}
	@Override
	public URL getDocumentBase() {
		// TODO Auto-generated method stub
		return null;
	}
	@Override
	public String getParameter(String name) {
		// TODO Auto-generated method stub
		return null;
	}
	@Override
	public boolean isActive() {
		// TODO Auto-generated method stub
		return false;
	}
	public final void setStub(AppletStub stub){
	}
}

whats next...


btw, maybe there is another way to create GUI for an applet without losing images loading?

Create an instance of your applet class:
yourApplet = new YourApplet();

Call its setStub() method passing it an instance of your class that implements AppletStub.
yourApplet.setStub(new MyStub());

Put println statements in all the MyStub class's methods and see which are called by your applet when it is executed.

Add code to those methods to do what they need to do.

Can you post the source code that has the error?
And the full text of the compiler's error messages.

The code for setting the AppletStub goes with the applet you are using in post#1. Not in the AppletStub class.
After you create an instance of your applet class, call its setStub() method.

Are you trying to draw images or display an existing image? if you want your applet to work without a browser, then you would continue doing what I have suggested. It will take more code that way then writing new code for your app because you have to do everything that the browser would have done .

If you want to display an image look at the ImageIO class for ways to read an image file.

Those methods are for applets. If you are not going to execute the code as an applet in a browser, you need to get rid of those methods and use methods suitable for applications. Don't extend the applet class.

Which are you trying to write? An applet for a browser or an app for a PC?

If you want to read an image from a disk file use the ImageIO class's methods.

Get rid of the applet class's methods and use the ImageIO class's read methods to read the image files.
Will the images be in the jar file or outside of it?
If inside you should use the read(URL) method and get the URL by using the Class class's getResource() method.
If outside you could use other versions of the read() method

how to fix lag?

Take out the call to sleep(4000)

No idea without seeing the code.

A common mistake is to load the images every time they are displayed instead of doing it one time.