JPanel和JMenuBar到同一框架

Question

I can't seem to add both a JMenuBar and a JPanel to my frame?

How come?

Code:

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


public class Proj extends JFrame implements ActionListener {

Proj() {
setSize(400,300);
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLayout(new FlowLayout());
setVisible(true);

JMenuBar rodMenu = new JMenuBar();
JMenu menu = new JMenu("Vis");
JMenuItem men_item1 = new JMenuItem("Statestik");

JPanel wrapper = new JPanel();
wrapper.setPreferredSize(new Dimension(380, 240));
wrapper.setBorder(BorderFactory.createLineBorder(Color.black));

setJMenuBar(rodMenu);
rodMenu.add(menu);
menu.add(men_item1);

add(wrapper);
}

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

}

With this code, the panel isn't added, only the menu... If I remove the menu, then the panel appears.

Answer 1

What do you mean panel not appearing? I could see both menu and panel with this code!

If the problem still persist try moving the setSize(), setResizable() etc block down like

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;

public class Proj extends JFrame implements ActionListener {

    Proj() {
        JMenuBar rodMenu = new JMenuBar();
        JMenu menu = new JMenu("Vis");
        JMenuItem men_item1 = new JMenuItem("Statestik");

        JPanel wrapper = new JPanel();
        wrapper.setPreferredSize(new Dimension(380, 240));
        wrapper.setBorder(BorderFactory.createLineBorder(Color.black));

        setJMenuBar(rodMenu);
        rodMenu.add(menu);
        menu.add(men_item1);

        JButton b = new JButton("Test");
        wrapper.add(b);

        add(wrapper);

        setSize(400, 300);
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLayout(new FlowLayout());
        setVisible(true);
    }

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

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub

    }

}

Answer 2

Try adding with

this.getContentPane.add(wrapper)

instead of

add(wrapper)