Question

Here is my code I have written thus far, along with the errors I’m receiving. I’m sure I’ve done similar code before with no errors. I’m pretty sure I’m missing something stupid but I can’t figure it out or find anything on the web.

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

public class MyFrame extends JFrame {

    JPanel mainPanel = new JPanel();
    JButton editButton = new JButton("Edit");
    JPanel.add(editButton);
}

Error:

Syntax error on token(s), misplaced construct(s) - for the underlined '.' 
on the last line
Syntax error on token "editButton", VariableDeclaratorId expected after this 
token - for the underlined parameter within the brackets on the last line.

Answer 1

You’re trying to use it as if it’s a static method – which panel would you expect to add the edit button to? You need to call it on the mainPanel:

mainPanel.add(editButton);

However, you can’t do that in a class declaration – a statement like that has to be in a method or constructor. So you probably want:

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

public class MyFrame extends JFrame {       
    JPanel mainPanel = new JPanel();
    JButton editButton = new JButton("Edit");

    public MyFrame() {
        mainPanel.add(editButton);
    }
}

Or possibly put all the initialization into the constructor, and also make the variables final and private:

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

public class MyFrame extends JFrame {       
    private final JPanel mainPanel;
    private final JButton editButton;

    public MyFrame() {
        mainPanel = new JPanel();
        editButton = new JButton("Edit");
        mainPanel.add(editButton);
    }
}