JTextField input and output

Question

I'm trying to design a Mile to Nautical Mile calculator in Java.

I was able to create and run it okay through the console, but i'm having trouble learning how to do it in JFrames.

what im basically wanting to do is:

Have two text fields and a button, one text field miles and one for nautical miles, when you enter the amount into one then press the button the result will display in the other field.

I've pasted my code below

Not really sure what to do next

package Mile_Conversion;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;


import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

public class OwnWindow implements ActionListener{



    public static void main(String[] args) {
        MyJFrame();

    }

    public static void MyJFrame() {

        //JLabel
        JLabel start = new JLabel("Enter the amount below to calculate");
        start.setBounds(/*x*/70, -65/*Y*/, 270, 150); // x, y, width, height    x across, y down
        JLabel milecon = new JLabel("Miles");
        milecon.setBounds(154, 55, 50, 150);
        JLabel nautcon = new JLabel("Nautical Miles");
        nautcon.setBounds(135, -15, 150, 150);

        //JTextField
        JTextField miles = new JTextField();
        miles.setBounds(100, 140, 150, 25);
        JTextField nautical = new JTextField();
        nautical.setBounds(100, 70, 150, 25);

        double mile, nautmile;

    /*
            mile = nautmile * 0.868;

            nautmile = mile * 1.150; 
    */

        //JButton
        JButton convert = new JButton("Convert");
        convert.setBounds(250, 200, 90, 25);


        //JFrame
        JFrame window = new JFrame("Milage Conversion");
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setSize(400, 300);
        window.setVisible(true);
        window.setLayout(null);
        window.setResizable(false);
        window.add(start);
        window.add(miles);
        window.add(nautical);
        window.add(convert);
        window.add(milecon);
        window.add(nautcon);

    }

    @Override
    public void actionPerformed(ActionEvent e) {


    }
}

Answer 1

Welcome to the wonderful world of variable fonts, resolutions and DPI, where what it looks like on your screen will never match any one elses (okay, that's an exaggeration, but it feels like it :P)

In this world, layout managers are you friend. They will save you many, many, many hours of frustration and torment.

I'd recommend you have a read through;

• Using Layout Managers
• A Visual Guide to Layout Managers

This is my take on what you are trying to do...

public class TestConvertDistance {

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

    public TestConvertDistance() {

        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new DistancePane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    protected class DistancePane extends JPanel {

        private JLabel lblInstruct;
        private JLabel lblMiles;
        private JLabel lblNauticalMiles;

        private JTextField fldMiles;
        private JTextField fldNauticalMiles;

        private JButton btnCalculate;

        public DistancePane() {

            lblInstruct = new JLabel("Enter the amount below to calculate");
            lblMiles = new JLabel("Miles");
            lblNauticalMiles = new JLabel("Nautical Miles");

            fldMiles = new JTextField(8);
            fldNauticalMiles = new JTextField(8);

            btnCalculate = new JButton("Convert");

            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
            gbc.insets = new Insets(2, 2, 2, 2);
            gbc.anchor = GridBagConstraints.WEST;
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            add(lblInstruct, gbc);

            gbc.gridx = 0;
            gbc.gridy++;
            gbc.anchor = GridBagConstraints.WEST;
            gbc.gridwidth = 1;
            add(lblMiles, gbc);

            gbc.gridy++;
            add(lblNauticalMiles, gbc);

            gbc.gridx = 1;
            gbc.gridy = 1;
            add(fldMiles, gbc);

            gbc.gridy++;
            add(fldNauticalMiles, gbc);

            gbc.gridx = 0;
            gbc.gridy++;
            gbc.anchor = GridBagConstraints.CENTER;
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            add(btnCalculate, gbc);

            btnCalculate.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    // Do your calculation here...
                }
            });

        }

    }

}

Note, I've used GridBagLayout, this is one of the most powerful and complicated layout managers in the core API, so don't get worried if at first it seems confusion ;)