How to fix the position of the JPanels after expanding the JFrame

Question

I am trying to make the interface of a program using Java Swing. I have a container where I add 3 JPanels with some components. The problem is that when I expand the frame all those 3 JPanels come on the first row one next to another.

Here is my code:

import java.awt.Color;
import java.awt.Container;
import java.awt.FlowLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SpringLayout;
import javax.swing.border.LineBorder;

public class GraphicRefact extends JFrame {
    private Container container;

    private JButton button2;
    private JButton button1;
    private JTextField textField01;
    private JLabel label01;

    private JButton button03;
    private JButton button04;
    private JTextField textField03;
    private JLabel label03;

    private JButton button02;
    private JButton button01;
    private JTextField textField02;
    private JLabel label02;

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

    public GraphicRefact() {
        initializeComponents();

        setTitle("Title");
        setSize(500, 150);
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        container = new JPanel();


        JPanel panel01 = new JPanel();

        panel01.add(label01);
        panel01.add(textField01);
        panel01.add(button2);
        panel01.add(button1);
        panel01.setBorder(new LineBorder(Color.BLACK, 3));
        container.add(panel01);



        JPanel panel02 = new JPanel();

        panel02.add(label02);
        panel02.add(textField02);
        panel02.add(button02);
        panel02.add(button01);
        container.add(panel02);

        JPanel panel03 = new JPanel();

        panel03.add(label03);
        panel03.add(textField03);
        panel03.add(button03);
        panel03.add(button04);
        container.add(panel03);

        add(container);

    }

    private void initializeComponents() {

        button1 = new JButton("Open");
        button2 = new JButton("Close");
        textField01 = new JTextField("Choose the path...");
        label01 = new JLabel("Choose File: ");

        button01 = new JButton("Button01");
        button02 = new JButton("Button02");
        textField02 = new JTextField("Choose the path...");
        label02 = new JLabel("Choose Dir:");

        button03 = new JButton("Button03");
        button04 = new JButton("Button03");
        textField03 = new JTextField("Choose the path...");
        label03 = new JLabel("Choose Dir:");
    }

}

Here is how the program looks before and after I expand the frame.

Before:

After:

So, even after I expand the frame, I want the program to leave those 3 JPanels on the middle of cotainer.

Thank you!

Answer 1

You can set the gridLayout and put those elements inside.

JPanel jp = new JPanel();
GridLayout gl = new GridLayout(3,4); //3 rows, 4 columns
jp.setLayout(gl);

After you do this, just put your elements inside layout, by order.

jp.add(label1);
jp.add(button1);
//etc...