chapter16n2.java

温度转换

/**
 *
 * demonstration of AWT - use of text fields for thermometer
 *
 * Written by: Roger Garside
 *
 * First Written: 11/July/96
 * Last Rewritten: 30/May/97
 *
 */

import java.awt.* ;
import java.awt.event.* ;

public class Chapter16n2 extends Frame
				implements WindowListener, ActionListener
    {
    Temperature temp1 ;

    private TextField celsiusField,
		fahrField ;
    private Canvas2 canvas ;
    private Button toF, toC, quit ;

    /**
     *
     * constructor
     *
     */

    public Chapter16n2()
	{
        temp1 = new Temperature() ;

	// set up basic window
	setTitle("Chapter16n2") ;
        setBackground(Color.green) ;
        setSize(400, 600) ;
        addWindowListener(this) ;

	// set up area for the thermometer
        canvas = new Canvas2(this) ;
	add("Center", canvas) ;

	// set up the panel of buttons and text fields

	// set up the first line of items
	Panel p1 = new Panel() ;
	p1.setLayout(new FlowLayout()) ;
	p1.add(new Label("Celsius")) ;
        celsiusField = new TextField("", 8) ;
	p1.add(celsiusField) ;
        toF = new Button("Convert to F") ;
	p1.add(toF) ;
        toF.addActionListener(this) ;

	// set up the second line of items
	Panel p2 = new Panel() ;
	p2.setLayout(new FlowLayout()) ;
	p2.add(new Label("Fahrenheit")) ;
        fahrField = new TextField("", 8) ;
	p2.add(fahrField) ;
	toC = new Button("Convert to C") ;
	p2.add(toC) ;
        toC.addActionListener(this) ;

	// set up the third line of items
	Panel p3 = new Panel() ;
	p3.setLayout(new FlowLayout()) ;
	quit = new Button("Quit") ;
	p3.add(quit) ;
        quit.addActionListener(this) ;

	Panel p = new Panel() ;
	p.setLayout(new BorderLayout()) ;
	p.add("North", p1) ;
	p.add("Center", p2) ;
	p.add("South", p3) ;
	add("South", p) ;
	} // end of constructor method

    /**
     *
     * main
     *
     */

    public static void main(String[] args)
        {
        Chapter16n2 f = new Chapter16n2() ;
        f.setVisible(true) ;
        } // end of main method

    /**
     *
     * actionPerformed
     *
     */

    public void actionPerformed(ActionEvent event)
        {
	// deal with "Quit" button
	if (event.getSource() == quit)
	    {
	    dispose();
	    System.exit(0);
	    }
	// deal with "Convert to Celsius" button
	else if (event.getSource() == toC)
	    {
	    String f1 = fahrField.getText() ;

	    double f2 = 0.0 ;
	    boolean isValid ;
	    try {
		f2 = Double.valueOf(f1).doubleValue() ;
		isValid = true ;
		}
            catch (NumberFormatException ex)
		{
		isValid = false ;
		}

            if (isValid)
		{
	        temp1.setFahr(f2) ;
	        double c2 = temp1.getCelsius() ;
	        c2 = ((double) Math.round(c2 * 100)) / 100 ;
	        String c1 = Double.toString(c2) ;
	        celsiusField.setText(c1) ;
		canvas.repaint() ;
		}
	    else
		{
	        fahrField.setText("") ;
		}
	    }
	// deal with "Convert to Fahrenheit" button
	else if (event.getSource() == toF)
	    {
	    String c1 = celsiusField.getText() ;

	    double c2 = 0.0 ;
	    boolean isValid ;
	    try {
		c2 = Double.valueOf(c1).doubleValue() ;
		isValid = true ;
		}
            catch (NumberFormatException ex)
		{
		isValid = false ;
		}
            if (isValid)
		{
	        temp1.setCelsius(c2) ;
	        double f2 = temp1.getFahr() ;
	        f2 = ((double) Math.round(f2 * 100)) / 100 ;
	        String f1 = Double.toString(f2) ;
	        fahrField.setText(f1) ;
		canvas.repaint() ;
		}
	    else
		{
	        celsiusField.setText("") ;
		}
	    }
        } // end of method actionPerformed

    /**
     *
     * windowClosing
     *
     */

    public void windowClosing(WindowEvent event)
        {
        dispose();
        System.exit(0);
        } // end of method windowClosing

    public void windowOpened(WindowEvent event) {}
    public void windowIconified(WindowEvent event) {}
    public void windowDeiconified(WindowEvent event) {}
    public void windowClosed(WindowEvent event) {}
    public void windowActivated(WindowEvent event) {}
    public void windowDeactivated(WindowEvent event) {}
    } // end of class Chapter16n2

class Canvas2 extends Canvas
    {
    Chapter16n2 parent ;

    /**
     *
     * constructor
     *
     */

    public Canvas2(Chapter16n2 f)
        {
        parent = f ;
        } // end of constructor method

    /**
     *
     * paint
     *
     */

    public void paint(Graphics g)
        {
	// set up some dimensions for the drawing
	Dimension d = getSize() ;
	int cx = d.width / 2,
	    cy = d.height / 2 + 150,
	    bulbInnerRadius = 40,
	    bulbOuterRadius = 50,
	    bulbInnerAngle = 20,
	    bulbOuterAngle = 20,
	    innerTubeRadius = 10,
	    outerTubeRadius = 20,
	    tubeLength = 300 ;

	// set up some dimensions for the text labels
	Font f1 = new Font("Helvetica", Font.BOLD, 14) ;
	FontMetrics fm1 = g.getFontMetrics(f1) ;
	int w0 = fm1.stringWidth("212F"),
	    h0 = (fm1.getAscent() / 2) ;

	// draw surrounding line
	g.setColor(Color.black) ;
	g.drawRoundRect(2, 2, d.width - 5, d.height - 5, 20, 20) ;

	// draw bulb
	g.setColor(Color.black) ;
	g.drawArc(cx - bulbOuterRadius,
		  cy - bulbOuterRadius,
		  bulbOuterRadius * 2,
		  bulbOuterRadius * 2,
		  90 + bulbOuterAngle,
		  360 - (2 * bulbOuterAngle)) ;
	g.drawArc(cx - bulbInnerRadius,
		  cy - bulbInnerRadius,
		  bulbInnerRadius * 2,
		  bulbInnerRadius * 2,
		  90 + bulbInnerAngle,
		  360 - (2 * bulbInnerAngle)) ;
	g.setColor(Color.red) ;
	g.fillOval(cx - bulbInnerRadius + 1,
		   cy - bulbInnerRadius + 1,
		   2 * (bulbInnerRadius - 1),
		   2 * (bulbInnerRadius - 1)) ;

	// draw tube
	g.setColor(Color.black) ;
	g.drawLine(cx - outerTubeRadius,
		   cy - bulbOuterRadius,
		   cx - outerTubeRadius,
		   cy - bulbOuterRadius - tubeLength) ;
	g.drawLine(cx - innerTubeRadius,
		   cy - bulbInnerRadius,
		   cx - innerTubeRadius,
		   cy - bulbOuterRadius - tubeLength) ;
	g.drawLine(cx + innerTubeRadius,
		   cy - bulbInnerRadius,
		   cx + innerTubeRadius,
		   cy - bulbOuterRadius - tubeLength) ;
	g.drawLine(cx + outerTubeRadius,
		   cy - bulbOuterRadius,
		   cx + outerTubeRadius,
		   cy - bulbOuterRadius - tubeLength) ;

	// draw cap
	g.setColor(Color.black) ;
	g.drawArc(cx - outerTubeRadius,
		  cy - bulbOuterRadius - tubeLength - outerTubeRadius,
		  2 * outerTubeRadius,
		  2 * outerTubeRadius,
		  0,
		  180) ;
	g.drawArc(cx - innerTubeRadius,
		  cy - bulbOuterRadius - tubeLength - innerTubeRadius,
		  2 * innerTubeRadius,
		  2 * innerTubeRadius,
		  0,
		  180) ;

	// draw marks
	g.setColor(Color.black) ;
	g.drawLine(cx - 40,
	           cy - bulbOuterRadius - 20,
		   cx - 30,
	           cy - bulbOuterRadius - 20) ;
	g.drawLine(cx + 40,
	           cy - bulbOuterRadius - 20,
		   cx + 30,
	           cy - bulbOuterRadius - 20) ;
	g.drawLine(cx - 40,
	           cy - bulbOuterRadius - tubeLength + 20,
		   cx - 30,
	           cy - bulbOuterRadius - tubeLength + 20) ;
	g.drawLine(cx + 40,
	           cy - bulbOuterRadius - tubeLength + 20,
		   cx + 30,
	           cy - bulbOuterRadius - tubeLength + 20) ;
	g.drawString("0C",
	             cx - 50 - w0,
		     cy - bulbOuterRadius - 20 + h0) ;
	g.drawString("32C",
	             cx + 50,
		     cy - bulbOuterRadius - 20 + h0) ;
	g.drawString("100C",
	             cx - 50 - w0,
		     cy - bulbOuterRadius - tubeLength + 20 + h0) ;
	g.drawString("212C",
	             cx + 50,
		     cy - bulbOuterRadius - tubeLength + 20 + h0) ;

	// draw mercury
	double tempC = parent.temp1.getCelsius() ;
	int mercuryLength ;
	if (tempC < - 11)
		mercuryLength = 0 ;
	else if (tempC < 120)
		mercuryLength = (int) (30 + (2.6 * tempC)) ;
	else
		mercuryLength = tubeLength ;
	g.setColor(Color.red) ;
	g.fillRect(cx - innerTubeRadius + 1,
		   cy - bulbInnerRadius - mercuryLength,
		   2 * innerTubeRadius,
		   mercuryLength) ;
	} // end of method paint
    } // end of class Canvas2