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Thread: Beginner: Error with 'extends JApplet'

  1. #1
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    Default Beginner: Error with 'extends JApplet'

    Hey,

    I have a bit of history with programming about 6 years ago with C++ when I dropped out of college. However, I am resuming my studies but the course has changed to a more Java based one so I am spending the next few months teaching myself Java. At the moment, I am waiting for a new book to arrive and am using an old version of Deitel and Deitel Java - How to Program, which references Netscape Communicator so enough said!

    Anyways, I'm just trudging towards the general tutorials and opening chapters and I've not got all the concepts straight in my head yet. The code is messy as I'm not doing anything with arrays yet.

    import javax.swing.JOptionPane;
    import java.awt.Graphics;
     
    public class PosNegZero extends JApplet
    {
     
    	String entry1, entry2, entry3, entry4, entry5; 
    	double ent1, ent2, ent3, ent4, ent5, noP, noN, no0;
     
     
    	public void init() {
     
    		no0 = 0 ; noP = 0; noN = 0;
    		entry1 = JOptionPane.showInputDialog("Enter 1st Number: ");
    		ent1 = Double.parseDouble (entry1);
    		entry2 = JOptionPane.showInputDialog("Enter 2nd Number: ");
    		ent2 = Double.parseDouble (entry2);
    		entry3 = JOptionPane.showInputDialog("Enter 3rd Number: ");
    		ent3 = Double.parseDouble (entry3);
    		entry4 = JOptionPane.showInputDialog("Enter 4th Number: ");
    		ent4 = Double.parseDouble (entry4);
    		entry5 = JOptionPane.showInputDialog("Enter 5th Number: ");
    		ent5 = Double.parseDouble (entry5);
     
    		if (ent1 == 0)
    			no0++;
    		else if (ent1 > 0)
    			noP++;
    		else if (ent1 < 0)
    			noN++;
     
    		if (ent2 == 0)
    			no0++;
    		else if (ent2 > 0)
    			noP++;
    		else if (ent2 < 0)
    			noN++;
     
    		if (ent3 == 0)
    			no0++;
    		else if (ent3 > 0)
    			noP++;
    		else if (ent3 < 0)
    			noN++;
     
    		if (ent4 == 0)
    			no0++;
    		else if (ent4 > 0)
    			noP++;
    		else if (ent4 < 0)
    			noN++;
     
    		if (ent5 == 0)
    			no0++;
    		else if (ent5 > 0)
    			noP++;
    		else if (ent5 < 0)
    			noN++;
     
    	}
     
     
     
    public void paint (Graphics g)
    {
    	g.drawString(no0 + " zero numbers\n" + noP + " positive numbers\n" + noN + " negative numbers\n", 25, 25);
    }
     
    }

    What I think I am doing is declaring an overall Class PosNegZero, and declaring global String and Double variables to be used in the classes init() and print(Graphics g)

    The error I am getting is JApplet cannot be resolved to a type

    The error could be down to me either not using the variables properly or not understanding Applets. I can output the same code to a command line or using showMessage but I want to use an applet for the purposes of this book question.

    Thanks!


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Beginner: Error with 'extends JApplet'

    You forgot to import JApplet.
    Useful links: How to Ask Questions the Smart Way | Use Code Tags | Java Tutorials
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  3. The Following User Says Thank You to KevinWorkman For This Useful Post:

    chrisob (April 17th, 2012)

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    Default Re: Beginner: Error with 'extends JApplet'

    Argh! I had done it in a previous example and just used import javax.swing.* rather than import JApplet and JOptionPane!

    Is it better to just use swing.* or awt.* unless you need to call a subdirectory?

    Oh, and thanks!

  5. #4
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    Default Re: Beginner: Error with 'extends JApplet'

    I like to use the full import statement without any wildcards, just because it lets you know exactly what you're using in that class. Wildcards don't add any overhead, they just make it less clear what the class is doing.
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    Default Re: Beginner: Error with 'extends JApplet'

    I'm sure it will make more sense to me (classes and importing etc) once I get a bit more practice. Expect to see a lot of me!!!

    Thanks again! This is why I miss doing this in college as it's good to have heads to throw things at!

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