Problem setting Preferredsize for JButton

[Blink383]

My problem is setting the size of the JButton. I want it to be a little button centered below the "Hello World" JLabel field (as it is now it spans the full width of the JFrame). I am unsure what is causing the setPreferredsize to be ignored. I am an ameture/novice Java Developer and appriciate any help and all help. My code is below error free:

/* Author: Ashley
 * This program will display a basic JFrame, JLabel, and JButton.
 * The JLabel will display "Hello World and the JButton will close the program
 */

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

/**
 *
 * @author Ashley
 */
public class gui extends JFrame implements ActionListener {


    public static void main(String[] args) {  //main arguments string

        gui gui = new gui();  // calls gui which holds all the GUI data

        /**
         *  method declaration for the gui 
         */
    }

    public gui() {

        String text = "Hello World!";  // creates a string for hello world
        JButton button; // names a JButton                

        JFrame frame = new JFrame("My GUI"); // creates a JFrame named fram

        frame.setSize(250, 150); // sets frame size 
        frame.setVisible(true); // makes frame visable
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //creates default close functions

        JPanel tpanel = new JPanel();  //creats a JPanel to hold the JLabel
        JLabel label = new JLabel( text ); //creats a JLabel
        label.setHorizontalAlignment(SwingConstants.CENTER); // sets JLabel middle and centered


        tpanel.add(label); // adds JLabel to the panel

        button = new JButton("OK");    // creates JButton
        Dimension bd = new Dimension(50, 50);
        button.setPreferredSize(bd);

        button.addActionListener(new ActionListener() { // add an action listener with inner class to declare JButton event
            @Override
            public void actionPerformed(ActionEvent e) { //inner class assigns action to button
                System.exit(0);
            }
        });

        frame.add(label, BorderLayout.CENTER); // addes JLabel to the JFrame
        frame.add(button, BorderLayout.SOUTH);// adds JButton to the JFrame



    }

    @Override  // an override for inner class, ensures that the button action will run. 
    public void actionPerformed(ActionEvent ae) {
    }
}

[kvprajapati]

Do not add button into contentPane of JFrame directly instead create a JPanel (with FlowLayout) and add that button in it.

JPanel bottom=new JPanel();
bottom.add(button);  
frame.add(bottom, BorderLayout.SOUTH);

[Blink383]

Excellent thank you! Worked perfectly and helped put a little light into building GUI's. This is my first Java GUI. I am working on my next class assignment and needed to make sure I could size buttons accordingly. =)

Thanks again ~ Problem solved!

[Mauricio Guillermo]

No. The problem is caused by the layout. Before adding anything to a JFrame or a JPanel, you have to setLayout(null). Otherwise, you'll have unexpected behaviours all the time. I just figured it out by myself after three hours of experimenting; suddenly, I connected your post with other different subject, and it worked, but this isn't well explained on the Internet yet.

[JamesCherrill]

Wrong wrong wrong. Terrible advice.
Layout managers are essential for creating apps that run on screens with different resolutions or different fonts.
You need to learn to use them, not turn them off.
See https://docs.oracle.com/javase/tutorial/uiswing/layout/index.html