how to put a table and 3 buttons in a JFrame

Question

Hi friends I want to layout 4 entities in one frame

1. A JTable
2. 3 buttons

For this I created a JFrame and put 2 JPanels inside that JFrame. One JPanel contains a scrollablePanel which holds a JTable. And another JPanel contains 3 JButtons.

I expected the output to be like below:

But My table is not visible anymore, only the buttons are visible. Following is my code

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

public class displayGui extends JFrame{
    private JPanel topPanel;
    private JPanel btnPanel;
    private JScrollPane scrollPane;

    public displayGui(JTable tbl){
        setTitle("Company Record Application");
        setSize(300,200);
        setBackground(Color.gray);


        topPanel = new JPanel();
        btnPanel = new JPanel();

        topPanel.setLayout(new BorderLayout());
        getContentPane().add(topPanel);
        getContentPane().add(btnPanel);
        scrollPane = new JScrollPane(tbl);
        topPanel.add(scrollPane,BorderLayout.CENTER);
        JButton addButton = new JButton("ADD");
        JButton delButton = new JButton("DELETE");
        JButton saveButton = new JButton("SAVE");

        btnPanel.add(addButton);
        btnPanel.add(delButton);

    }
}

The code in my main method:

displayGui dg = new displayGui(table);
dg.setVisible(true);

Answer 1

You need to specify a location for each panel on the frame...

Instead of...

getContentPane().add(topPanel);
getContentPane().add(btnPanel);

Try...

getContentPane().add(topPanel, BorderLayout.CENTER);
getContentPane().add(btnPanel, BorderLayout.SOUTH);

Side Note

The JFrame s add method automatically redirects calls to it to the the contentPane , so, technically, you only need to do ...

add(topPanel, BorderLayout.CENTER);
add(btnPanel, BorderLayout.SOUTH);

Updated

I should also point out that the default layout manager for a JFrame is BorderLayout . You can change this by simply calling JFrame#setLayout , but the result you're after is best meet with the BorderLayout ...FYI