/**************************************************************
* MathCalculator.java
* Dean & Dean
*
* This program uses embedded layout managers to display
* the square root and logarithm of a user-entered number.
**************************************************************/

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

public class MathCalculator extends JFrame
{
  private static final int WIDTH = 380;
  private static final int HEIGHT = 110;

  private JTextField xBox;     // user's input value
  private JTextField xSqrtBox; // generated square root
  private JTextField xLogBox;  // generated logarithm

  //***********************************************************

  public MathCalculator()
  {
    setTitle("Math Calculator");
    setSize(WIDTH, HEIGHT);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    createContents();
    setVisible(true);
  } // end MathCalculator constructor

  //***********************************************************

  // Create components and add to window.

  private void createContents()
  {
    JPanel xPanel;        // holds x label and its text box
    JPanel xSqrtPanel;    // holds "sqrt x" label and its text box
    JPanel xLogPanel;     // holds "log x" label and its text box
    JLabel xLabel;
    JButton xSqrtButton;
    JButton xLogButton;
    Listener listener;

    setLayout(new GridLayout(2, 2));

    // Create the x panel:
    xLabel = new JLabel("x:");
    xBox = new JTextField(8);
    xPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
    xPanel.add(xLabel);
    xPanel.add(xBox);

    // Create the square-root panel:
    xSqrtButton = new JButton("sqrt x");
    xSqrtBox = new JTextField(8);
    xSqrtBox.setEditable(false);
    xSqrtPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
    xSqrtPanel.add(xSqrtButton);
    xSqrtPanel.add(xSqrtBox);

    // Create the logarithm panel:
    xLogButton = new JButton("log10 x");
    xLogBox = new JTextField(8);
    xLogBox.setEditable(false);
    xLogPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
    xLogPanel.add(xLogButton);
    xLogPanel.add(xLogBox);

    // Add panels to the window:
    add(xPanel);
    add(xSqrtPanel);
    add(new JLabel());    // dummy component
    add(xLogPanel);

    listener = new Listener();
    xSqrtButton.addActionListener(listener);
    xLogButton.addActionListener(listener);
  } // end createContents

  //***********************************************************

  // Inner class for math calculations.

  private class Listener implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      double x;           // numeric value for user entered x
      double result;      // calculated value

      try
      {
        x = Double.parseDouble(xBox.getText());
      }
      catch (NumberFormatException nfe)
      {
        x = -1;           // indicates an invalid x
      }

      if (e.getActionCommand().equals("sqrt x"))
      {
        if (x < 0)
        {
          xSqrtBox.setText("undefined");
        }
        else
        {
          result = Math.sqrt(x);
          xSqrtBox.setText(String.format("%7.5f", result));
        }
      } // end if

      else // calculate logarithm
      {
        if (x < 0)
        {
          xLogBox.setText("undefined");
        }
        else
        {
          result = Math.log10(x);
          xLogBox.setText(String.format("%7.5f", result));
        }
      } // end else
    } // end actionPerformed
  } // end class Listener

  //**********************************************************

  public static void main(String[] args)
  {
    new MathCalculator();
  } // end main
} // end class MathCalculator