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Thread: My code doesn't have a main clss?

  1. #1
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    Default My code doesn't have a main clss?

    I'm trying to designa simple Minecraft launcher GUI and it's not working with Netbeans.

    I made a video launcher for my University coursework and it works fine; I based the Minecraft launcher off of that code and Netbeans just isn't running the file.

    Here is the code I have (for the Minecraft launcher):

    import java.awt*;
    import java.awt.event*;
    import javax.swing*;

    public class MinecraftWiki extends JFrame implements ActionListener {
    JButton search = new JButton("Search");
    JButton open = new JButton("Enter the Minecraft Wiki");
    JButton close = new JButton("Exit");

    public static void main(String[] args) {
    new MinecraftWiki();

    }

    public MinecraftWiki() {
    setLayout(new BorderLayout());
    setSize(500, 500);
    setTitle("Minecraft Wiki");

    setDefaultCloseOperation(WindowConstants.DO_NOTHIN G_ON_CLOSE);

    JPanel bottom = new JPanel();
    bottom.add(search); open.addActionListener(this);
    bottom.add(open); open.addActionListener(this);
    bottom.add(close); open.addActionListener(this);

    setResizable(false);
    setVisible(true);

    }

    public void actionPerformed(Action Event e) {
    if (e.getSource() == search) {
    new CheckWiki();
    } else if (e.getSource() == quit) {
    System.exit(0);

    }
    }
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: My code doesn't have a main clss?

    Netbeans just isn't running the file.
    Please explain. Are there any errors? Copy them and paste them here.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: My code doesn't have a main clss?

    Have you made sure netbeans knows this is the main class it needs to run? Its in the project properties, under the "run" tab you can select which class you want netbeans to run. Or just try shift+F6 to run the main class whilst its open. Hope this is what you were looking for

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    Default Re: My code doesn't have a main clss?

    Quote Originally Posted by Norm View Post
    Please explain. Are there any errors? Copy them and paste them here.
    This is the error that comes up:
    Exception in thread "main" java.lang.VerifyError: (class: MinecraftWiki, method: <init> signature: ()V) Constructor must call super() or this()
    Java Result: 1

    BUILD SUCCESSFUL (total time: 2 seconds)

    --- Update ---

    Quote Originally Posted by rossc View Post
    Have you made sure netbeans knows this is the main class it needs to run? Its in the project properties, under the "run" tab you can select which class you want netbeans to run. Or just try shift+F6 to run the main class whilst its open. Hope this is what you were looking for
    Yes, Netbeans knows.

    I always press F6 and go into the run tab.

  5. #5
    Super Moderator Norm's Avatar
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    Default Re: My code doesn't have a main clss?

    Is that all of the error message? Normal print outs of error messages give the location where the error happened.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default

    F6 runs the project, shift+F6 runs the individual class/java file. But that's not your issue it's asking for a super method in the constructor I think judging on that error message, although I didn't think JFrame has anything to need to call super() let me just check...

  7. #7
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    Default Re: My code doesn't have a main clss?

    Compile your code before you attempt to run it. What you posted won't compile and the compiler's message will be useful.

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    Default

    Try adding super() as the first line in your constructor and just see if that works

  9. #9
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    Default Re: My code doesn't have a main clss?

    Try...
    JFrame has a no-arg constructor.

    The problem here is that the code, as posted, will not compile. Consequently NB's verifier is going to grumble about whatever (old) class files it is looking at. The thing to do is to compile the code successfully (ie respond to the compiler's messages) before attempting to run it.

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    Default Re: My code doesn't have a main clss?

    Quote Originally Posted by Norm View Post
    Is that all of the error message? Normal print outs of error messages give the location where the error happened.
    Here are some screenshots:
    p6Pgk.jpg

    dSkOL.png

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    Default Re: My code doesn't have a main clss?

    Quote Originally Posted by pbrockway2 View Post
    JFrame has a no-arg constructor.

    The problem here is that the code, as posted, will not compile. Consequently NB's verifier is going to grumble about whatever (old) class files it is looking at. The thing to do is to compile the code successfully (ie respond to the compiler's messages) before attempting to run it.
    I was never taught how to compile a piece of code... I don't think.

    How do you do that?

  12. #12
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    Default Re: My code doesn't have a main clss?

    If you don't understand my answer, don't ignore it, ask a question.

  13. #13
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    Default Re: My code doesn't have a main clss?

    Those red squiggly things in the screen shots are compiler messages indicating a problem with the code. They all have to be fixed, which is not has hard as it might seem.

    I agree with Norm, if you can't coax a reasonable description of the problem(s) out of NB, compile your code at the command line. If the Tutorial instructions don't make sense, post back and say what you've done and what happened. The compiler will produce a *lot* of output: one for each red squiggled line. That's normal. Deal with whatever you can and post whatever remains here, and I'm sure someone can explain what each means so you can fix it.

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    Default

    Have you import the correct packages?

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    Default Re: My code doesn't have a main clss?

    Quote Originally Posted by pbrockway2 View Post
    Those red squiggly things in the screen shots are compiler messages indicating a problem with the code. They all have to be fixed, which is not has hard as it might seem.

    I agree with Norm, if you can't coax a reasonable description of the problem(s) out of NB, compile your code at the command line. If the Tutorial instructions don't make sense, post back and say what you've done and what happened. The compiler will produce a *lot* of output: one for each red squiggled line. That's normal. Deal with whatever you can and post whatever remains here, and I'm sure someone can explain what each means so you can fix it.
    Ok, I'll look at the tutorial now

    --- Update ---

    Quote Originally Posted by rossc View Post
    Have you import the correct packages?
    Yes

    --- Update ---

    I tried to compile the code in Netbeans, but it says I've already compiled it.

    I read the tutorials but I can't see my JDK 7 platform

  16. #16
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    Default Re: My code doesn't have a main clss?

    I read the tutorials but I can't see my JDK 7 platform
    The link Norm provided only requires you to choose your operating system. It is written with JDK 7 in mind.

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    Default Re: My code doesn't have a main clss?

    errors::
    1.you missed "." while importing
    ex:import java.awt.*;
    2.please check the parameters of setDefaultyCloseOperation
    its DO_NOTHING_ON_CLOSE
    3.parameter of actionPerformed()
    its ActionEvent (no space between them)
    4.finally..you don't have any variable as "exit"
    its "close" i assume

    and considering you have written the class CheckWiki()

    thats all of the errors in your code
    Last edited by rougeking; January 11th, 2013 at 02:33 PM. Reason: Please don't spooonfeed code

  18. #18
    Super Moderator pbrockway2's Avatar
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    Default offtopic

    @rougeking: thanks for removing the code. My first thought when I see something full of typos is to say "Here, do it like this..." but I'm convinced of the futility of this approach as it demonstrates what would be right but doesn't address question of what was wrong. Since similar problems are *certain* to occur again, an understanding of what was wrong is much more valuable.

    In the OP's case, he or she still has to deal with NB's perverse willingness to attempt to run defective code and the consequent very cryptic runtime messages. Also there's the basic question of what compilation is and how you compile. The Tutorial link addresses exactly that.

    A little point but when you do post code the appropriate tags have square brackets: [code] ... [/code]

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