Add a class from different package and add it to JTabbedPane

[John Path]

Hello there,

I have a class Staff which has a JTabbedPane. I want to add a JPanel in the JTabbedPane from another class UpdateProfile (which is on another package). Can anyone help me with that.
I am new to java and recently i moved from gui builder to manual coding so i need a help here. I know its pretty confusing but please take a time to solve this problem.

    // This is a constructor of class Staff
    public Staff() {

        JTabbedPane window = new JTabbedPane();
        JPanel update = new UpdateProfile(); // error here help!!
        
        window.add(update);
        window.setVisible(true);
    }

In the above TabbedPane i want to add the class have constructor as below

    public UpdateProfile() {
        JPanel update = new JPanel();
        update.setLayout(null);
        
        JButton clearUpdateButton = new JButton("Hello");

        update.add(clearUpdateButton);
        update.setVisible(true);
    }

[Piet Souris]

hi John,

is your class 'UpdateProfile' a class that extends JPanel? If not, then update in line 5 cannot be of type JPanel

[Paul Clapham]

Even more confusing without knowing what the error message says. However... if your UpdateProfile class is going to contain a JPanel, as in your constructor code, then it will need a getter method for users of the class (such as your Staff class) to get a reference to that JPanel. Right now you only have a local variable in the constructor which refers to the JPanel, so you'd need to fix the UpdateProfile class to have an instance variable to hold that reference.

Or if the UpdateProfile class is intended to actually be a JPanel, as Piet guesses, then it should extend JPanel instead of creating one.

[John Path]

thanks guys for your help,

Now UpdateProfile Class extends JPanel,

But still i am finding errors

Staffs Constructor

   // This is a constructor of class Staff
   public Staff() {
 
       JTabbedPane window = new JTabbedPane();
       JPanel update = new UpdateProfile(); 
        
       window.add(update);
       window.setVisible(true);
   }

UpdateProfile Constructor now it extends JPanel

   public UpdateProfile() {
       setLayout(null);
        
       JButton clearUpdateButton = new JButton("Hello");
 
       add(clearUpdateButton);
       setVisible(true);
   }

While running managingSTaff class it shows the following error

Exception in thread "main" java.lang.NullPointerException: Cannot read field "parent" because "comp" is null

[Paul Clapham]

This appears to be an error message from some code you haven't shown us. Or am I wrong?

It would be more helpful to show us the whole stack trace and not just one line of it. That way it's possible to identify the context in which the error occurred.

[Rob Camick]

Post a proper SSCCE when asking a question.

We can't guess the context of how the code snippets are used.