Why is setting setPreferredSize () on a JFrame bad?

Sets the preferred size JFrame

using setPreferredSize()

what is considered bad?

If this is bad, then there is a good way to resize the window JFrame

to the size I need.

I know how to compose the components to reflect the final JFrame dimension that I need. But if I use a shortcut to change the preferred size with a call setPreferredSize()

just before the call pack()

to change the final size JFrame

, is that bad? If so, why?

For example, I have a sample form:

This is displayed without setting the preferred size.

Now I can resize the form with call setPreferredSize()

before call pack()

.

This is displayed when called: setPreferredSize(new Dimension(500, 300));

I can have a similar effect when adjusting the size of the components when installing it. But what is the disadvantage of setting the frame size with just a call setPreferredSize()

.

I might think that the preferred size can be changed by manually resizing the displayed window with the mouse after it is displayed. Is not it?

code:

import java.awt.Dimension;

import javax.swing.GroupLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class MyFrame extends JFrame {
    private static final long serialVersionUID = 1L;

    private JTextField fullNameTextField = new JTextField();
    private JTextField emailIDTextField = new JTextField();
    private JTextArea addressTextArea = new JTextArea();
    private JButton submitButton = new JButton("Submit");
    private JButton cancelButton = new JButton("Cancel");

    public MyFrame(){
        super("MyFrame");

        layoutComponents();

        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationByPlatform(true);

        setPreferredSize(new Dimension(500, 300));

        pack();
    }

    private void layoutComponents(){
        GroupLayout layout = new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);

        JLabel fullNameLabel = new JLabel("Full Name:");
        JLabel emailIDLabel = new JLabel("Email ID:");
        JLabel addressLabel = new JLabel("Address:");

        JScrollPane addressScrollPane = new JScrollPane(addressTextArea);

        layout.setHorizontalGroup(
                layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                        .addGap(10)
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                                .addGroup(layout.createSequentialGroup()
                                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                                                .addComponent(fullNameLabel)
                                                .addComponent(emailIDLabel)
                                                .addComponent(addressLabel)
                                            )
                                        .addGap(15)
                                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                                                .addComponent(fullNameTextField, 10, 200, Short.MAX_VALUE)
                                                .addComponent(emailIDTextField)
                                                .addComponent(addressScrollPane)
                                                .addGroup(layout.createSequentialGroup()
                                                        .addGap(0, 0, Short.MAX_VALUE)
                                                        .addComponent(submitButton)
                                                        .addGap(10)
                                                        .addComponent(cancelButton)
                                                    )
                                            )
                                    )
                            )
                        .addGap(10)
                    )
            );

        layout.setVerticalGroup(
                layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                        .addGap(10)
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                .addComponent(fullNameLabel)
                                .addComponent(fullNameTextField)
                            )
                        .addGap(5)
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                .addComponent(emailIDLabel)
                                .addComponent(emailIDTextField)
                            )
                        .addGap(5)
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                .addComponent(addressLabel)
                                .addComponent(addressScrollPane, 20, 60, Short.MAX_VALUE)
                            )
                        .addGap(15)
                        .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                .addComponent(submitButton)
                                .addComponent(cancelButton)
                            )
                        .addGap(10)
                    )
            );

        layout.linkSize(submitButton, cancelButton);

        getRootPane().setDefaultButton(submitButton);
    }

    public static void main(String [] args){
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new MyFrame().setVisible(true);
            }
        });
    }
}