thebbqcode

/*
 * Simple Converter suitable for anything
 * demonstration very basic GUI Java
 */
 
/**
 *
 * @author bbq
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class BasicConverter extends JFrame implements ActionListener
{
 
    // Constructor //
    public BasicConverter(String windowTitle)
    {
        // begin setting up properties of our main //
        // JFrame                                  //
        super(windowTitle);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.setLayout( new BorderLayout() ); // user card layout so we have more options
        this.setSize(300,110);
 
        // call our function to init the components //
        this.initComponents();
 
    }
 
    // function to initialise all our componenets //
    // to be used on JFrame                       //
    private void initComponents()
    {
        // firstly instantiate our components //
 
        // Panels Firstly - set their layouts also //
        this.inputPanel = new JPanel();
        this.inputPanel.setLayout(new GridLayout(2,2,5,5));
 
        this.buttonPanel = new JPanel();
        this.buttonPanel.setLayout( new FlowLayout());
 
        // labels
        this.inputLabel  = new JLabel("Input");
        this.outputLabel = new JLabel("Output");
 
        //fields
        this.inputField  = new JTextField();
        this.outputField = new JTextField();
 
        // button - also add ActionListener to 'this' button
        this.convert = new JButton("Convert");
        this.convert.addActionListener(this);
 
        /*
         * now we have instantiated components and set some basic properties
         * we can now begin adding our components to their panels and then the
         * panels to our JFrame
         * 
         **/
 
        // Add components to the JPanel inputPanel              //
        // order is important because we are using GridLayout   //
        this.inputPanel.add( this.inputLabel );
        this.inputPanel.add( this.inputField );
        this.inputPanel.add( this.outputLabel );
        this.inputPanel.add( this.outputField );
 
        // Add components to the JPanel buttonPanel             //
        // add it so it aligns in the center                    //
        this.buttonPanel.add( this.convert );
 
        // Now we can add our two panels to the main JFrame     //
        this.add( this.inputPanel, BorderLayout.NORTH );    // places inputPanel  at top
        this.add( this.buttonPanel, BorderLayout.SOUTH );   // places buttonPanel at bottom
 
 
    }
    private void convertInputValue()
    {
        // we will simply square the current input value //
        // you could do any calculation you wish         //
        double input = 0;
 
        try
        {
            // simply get the input from the input field and parse
            // it to something we want. In this case we want a double
            input = Double.parseDouble( this.inputField.getText() );
 
        } catch (Exception e)  {    this.inputField.setText( "Error " + e.getMessage() );  return;  }
                                    // if exception caught tell user what happened and return  //
        // square the input we received
        input = input * input;
 
        // update the output field accurate to 2 decimal places //
        this.outputField.setText( String.format("%.2f", input) );
 
 
    }
 
    // override functoin for our ActionListener
    public void actionPerformed(ActionEvent e)
    {
        // this function will be called for all objects we  //
        // addActionListener to, in this example we have    //
        // only done that for the button convert. so we do  //
        // as follows.                                      //
 
        if (e.getSource() == this.convert)
        {
            // we call our convertInputValue here             //
            // alternatively we could do our code in here, if //
            // it is as small as this.                        //
            this.convertInputValue();
        }
 
    }
 
    // Main Function
    public static void main(String[] args)
    {
        // this will call constructor and begin building the application frame //
        BasicConverter myConverter = new BasicConverter("Basic Converter - bbq");
        myConverter.setVisible(true);   // frame is ready to show once constructor is complete
                                        // show it
    }
 
    // Components needed
    private JPanel inputPanel;
    private JPanel buttonPanel;
 
    private JLabel inputLabel;
    private JLabel outputLabel;
    private JTextField inputField;
    private JTextField outputField;
    private JButton convert;
}