Java - JComboBox cannot be shown

Question

I just want to create a JComboBox. And, I paste the following code in https://www.compilejava.net/ and nothing is shown in the window. So, what's wrong with the code? Or does the online compiler have problems? If so, are there any online compiler that works?

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

public class test{

private JFrame f; //window
private JPanel p; //layout


private JComboBox<String> j; //pull down menu

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

public test(){
   f = new JFrame("title of window");
   f.setVisible(true); 
   f.setSize(600,400);
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

   p = new JPanel();
   p.setBackground(Color.YELLOW);

   String[] bookTitles = new String[] {"Effective Java", "Head First Java",
                                "Thinking in Java", "Java for Dummies"};
   JComboBox<String> bookList = new JComboBox<>(bookTitles);
   p.add(bookList);

   f.add(p);
}

}

Don't call `setVisible(true)` until **after** adding all components to your GUI. Else you're displaying it when it's unfinished. — Hovercraft Full Of Eels, Oct 01 '16 at 02:33
@HovercraftFullOfEels How come I can display JLabel when I call setVisible(true) before adding JLabel? — Keroro Chan, Oct 01 '16 at 02:35
What JLabel, as I seen no JLabel in the code above? Regardless, even if it works in one situation and not in another, it is recommended in general that you call `setVisible(true)` after adding components. It makes common sense, no? — Hovercraft Full Of Eels, Oct 01 '16 at 02:36
@HovercraftFullOfEels Thank you so much. I will call it at the last line — Keroro Chan, Oct 01 '16 at 02:38

Java - JComboBox cannot be shown

0 Answers0