Using Packages


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Thread: Using Packages

  1. #1
    Join Date
    Sep 2003
    Posts
    16

    Using Packages

    Hello,
    I'm relatively new to Java. I've made up a package and I'm trying to implement it in an Applet. I imported it. However, any time I try to use it, the applet gives an error message stating "Applet notinited". Anytime I try to use the class, imageFile f = new imageFile("somestringhere.jpg"); it gives the above error message. Any clues what the deal is? Is there anything different I need to do with an Applet when using packages?
    Jerod Brown

  2. #2
    Join Date
    Mar 2003
    Posts
    834

    Question

    What does the Java console say? (in IE, it's Tools -> Sun Java Console)

    Have you fully qualified your main applet file? e.g. com.sony.MyApplet
    ArchAngel.
    O:-)

  3. #3
    Join Date
    Sep 2003
    Posts
    16
    These are the messages its saying in the console:

    java.lang.NoClassDefFoundError: radss/imageFile
    java.lang.NullPointerException
    java.lang.NoClassDefFoundError: radss/imageFile

    I'm assuming there is something more that I must do to import and use packages? Something else I need to define when making that class?

    As far as your second question, I am not sure what you are asking.

    My main applet is temp.java and the class that I made is imageFile.java. Do I need to have temp.class and imageFile.class both in the same directory as the web page? Thats the way i currently have it. Do I need to make a folder for the package. Such as have temp.class in one directory, and make a directory with it for radss (the package name) and put the imageFile.class in there.

    Thanks for your help ...
    Jerod Brown

  4. #4
    Join Date
    Mar 2003
    Posts
    834
    In not sure if it's creating packages or using them that you don't understand, so I'll walk you through an example.

    1. Create a new folder called "test"

    2. Create in that folder a file called "Test.html":
    Code:
    <html>
    	<body>
    		<applet height="50", width="300" code="MainAppletFile.class">
    		</applet>
    	</body>
    </html>
    3. Create in that folder a file called "MainAppletFile.java":
    Code:
    import java.applet.Applet;
    import java.awt.Graphics;
    import net.trycatch.applet.FileInPackage;
    
    public class MainAppletFile extends Applet {
    	public void paint(Graphics g) {
    		FileInPackage fip = new FileInPackage("Hello World from inside a package!");
    		g.drawString(fip.getMessage(), 50, 25);
    	}
    }
    As you can see, we're using a class called "FileInPackage". We haven't created that yet...but here it comes....

    4. Create a new folder in "test" called "net".

    5. Create a new folder in "net" called "trycatch".

    6. Create a new folder in "trycatch" called "applet"

    7. Create a new file in "applet" called "FileInPackage.java":
    Code:
    package net.trycatch.applet;
    
    public class FileInPackage {
    
    	private String msg;
    
    	public FileInPackage(String msg) {
    		this.msg = msg;
    	}
    
    	public String getMessage() {
    		return this.msg;
    	}
    }
    8. Compile "FileInPackage.java".

    9. Move back to the "test" folder and compile "MainAppletFile.java".

    10. Open "Test.html" in your browser. You should see "Hello World from inside a package!".

    OK. There are the steps, now a little word about what we've done.

    We created an HTML file and referred to a file called "MainAppletFile.class" which is our main applet file. This file refers to a class called "net.trycatch.applet.FileInPackage". We therefore created a package hierarchy for the class (as you do when creating a package) and the class itself.

    Hope this helps.
    ArchAngel.
    O:-)

  5. #5
    Join Date
    Sep 2003
    Posts
    16
    Thanks Archangel.

    I was creating the package right (hence no compile errors), but I simply wasn't placing the other .class file in the appropiate spot on the server. Thanks again, and I'm sure I'll bug you some more.
    Jerod Brown

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