Thread: 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);

}
}
}

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

Originally Posted by Norm

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 ---

Originally Posted by rossc

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.

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...

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

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

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.

Originally Posted by Norm

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

Originally Posted by pbrockway2

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?

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.

Have you import the correct packages?

Originally Posted by pbrockway2

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 ---

Originally Posted by rossc

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

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.

@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]