Quick question about creating and instance and passing it to a constuctor in a GUI

So I have a question. I need to create and instance of CardManager. Which I do here.

Code:

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public static void main(String[] args)
        {
                new GUI2();
                new GUI();
                CardManager man = new CardManager();
               
        }

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I need to know how to pass the instance to a constructor in my GUI class.

Code:

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CardManager manage;
       
        public GUIpanel2(main m, CardManager manage)
        {
                super();
               
                this.manage = manage;
        }

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First hit for googling "java constructor": Passing Information to a Method or a Constructor (The Java™ Tutorials > Learning the Java Language > Classes and Objects)

Quote:

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Originally Posted by KevinWorkman

First hit for googling "java constructor": Passing Information to a Method or a Constructor (The Java™ Tutorials > Learning the Java Language > Classes and Objects)

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I'm aware of that but does not answer my question.

Quote:

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Originally Posted by jokkycaz

I'm aware of that but does not answer my question.

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What about it didn't you understand? Perhaps read the actual start to that tutorial: Providing Constructors for Your Classes (The Java™ Tutorials > Learning the Java Language > Classes and Objects)

I defiantly read that a few hours ago. I know how to pass information to a constructor in the same class. I do not know how to pass an instance to two seperate constructors OUTSIDE of the main program. Am I missing where it talks about that in the link?

Code:

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CardManager man = new CardManager();
                Panel2 panel = new Panel2(man);
                GUIpanel2 panel1 = new GUIpanel2(man);

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This doesn't work not sure why.

Quote:

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This doesn't work

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What happens? "doesn't work" is not a useful description of the problem.
Does GUIpanel2 have more constructors than the one you posted in post#1.
That one shows that the constructor takes 2 arguments, not the single one you show in post#5

its supposed to have only 1. I was experimenting with different things.

Code:

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CardManager manage;
       
        public GUIpanel2(CardManager manage)
        {
                this.manage = manage;
        }

---

Code:

---

public class main
{
        public static void main(String[] args)
        {
                new GUI2();
                new GUI();
                CardManager man = new CardManager();
               
        }
}

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In my panel class i am trying to open a credit card. When i do this i get that the credit card i opened is null.

[CODE]
public class OpenAccount implements ActionListener
{
public void actionPerformed(ActionEvent e)
{

String n = name.getText();
if(name.getText().trim().length() != 0)
{
id2 = manage.openCreditCard(n, 5000.0, 5.0);
String id1 = Integer.toString(id2);
id.setText(id1);
}
else
JOptionPane.showMessageDialog(null, "Please enter a name");

}
}
[\CODE]

Quote:

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When i do this i get that the credit card i opened is null.

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Can you show the error message and the code that generated it?

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at GUIpanel2$OpenAccount.actionPerformed(GUIpanel2.ja va:51)

Code:

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public class OpenAccount implements ActionListener
        {
                public void actionPerformed(ActionEvent e)
                {
                       
                        String n = name.getText();
                        if(name.getText().trim().length() != 0)
                        {
                                [B]id2 = manage.openCreditCard(n, 5000.0, 5.0);[/B]
                                String id1 = Integer.toString(id2);
                                id.setText(id1);
                        }
                        else
                                JOptionPane.showMessageDialog(null, "Please enter a name");
                       
                }
        }

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The bold is causing it

To explain it better. I have a Panel that basically allows a person to put there name in and they can open a creditcard. I have a class called CardManager that does the creating of the creditcards. I have a main program and i have to open the instance of CardManager and then pass it to my gui panel so i can open a credit card with that

Is the manage variable null?
Where is it given a value?

Yes manage is null. When the gui is ran all the person has to enter is a name. I have the automatically set. aka the interest and balance

Quote:

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Yes manage is null.

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Then you can't do this:
manage.openCreditCard(n, 5000.0, 5.0);

Quote:

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Originally Posted by Norm

Then you can't do this:
manage.openCreditCard(n, 5000.0, 5.0);

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? I already have that exact code.

How can I get the variable man in my main program into my constructor in GUIpanel2?

The main program will create an instance of the CardManager and then pass it to the Banker and User gui constructors.

^ this is what i cant figure out

Quote:

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How can I get the variable man in my main program into my constructor in GUIpanel2?

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You have already shown you know how to do this. Please explain your problem.

Code:

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              CardManager man = new CardManager();  // Create an instance of the CardManager
                ...
              GUIpanel2 panel1 = new GUIpanel2(man);  // pass a reference to it to the constructor

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Perhaps if you wrote a small simple program that compiles to show your problem. The short bits of code you have posted don't show what the problem is.