/* * * Copyright (c) 2007, Sun Microsystems, Inc. * * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * *  * Redistributions of source code must retain the above copyright *    notice, this list of conditions and the following disclaimer. *  * Redistributions in binary form must reproduce the above copyright *    notice, this list of conditions and the following disclaimer in the *    documentation and/or other materials provided with the distribution. *  * Neither the name of Sun Microsystems nor the names of its contributors *    may be used to endorse or promote products derived from this software *    without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */package calculator;import javax.microedition.lcdui.*;import javax.microedition.midlet.MIDlet;/** * The calculator demo is a simple floating point calculator * which powered by floating point support available in cldc1.1. * * @version */public final class CalculatorMIDlet extends MIDlet implements CommandListener {    /** The number of characters in numeric text field. */    private static final int NUM_SIZE = 20;    /** Soft button for exiting the game. */    private final Command exitCmd = new Command("Exit", Command.EXIT, 2);    /** Menu item for changing game levels. */    private final Command calcCmd = new Command("Calc", Command.SCREEN, 1);    /** A text field to keep the first argument. */    private final TextField t1 = new TextField(null, "", NUM_SIZE, TextField.DECIMAL);    /** A text field to keep the second argument. */    private final TextField t2 = new TextField(null, "", NUM_SIZE, TextField.DECIMAL);    /** A text field to keep the result of calculation. */    private final TextField tr = new TextField("Result", "", NUM_SIZE, TextField.UNEDITABLE);    /** A choice group with available operations. */    private final ChoiceGroup cg =        new ChoiceGroup("", ChoiceGroup.POPUP,            new String[] { "add", "subtract", "multiply", "divide" }, null);    /** An alert to be reused for different errors. */    private final Alert alert = new Alert("Error", "", null, AlertType.ERROR);    /** Indicates if the application is initialized. */    private boolean isInitialized = false;    /**     * Creates the calculator view and action buttons.     */    protected void startApp() {        if (isInitialized) {            return;        }        Form f = new Form("FP Calculator");        f.append(t1);        f.append(cg);        f.append(t2);        f.append(tr);        f.addCommand(exitCmd);        f.addCommand(calcCmd);        f.setCommandListener(this);        Display.getDisplay(this).setCurrent(f);        alert.addCommand(new Command("Back", Command.SCREEN, 1));        isInitialized = true;    }    /**     * Does nothing. Redefinition is required by MIDlet class.     */    protected void destroyApp(boolean unconditional) {    }    /**     * Does nothing. Redefinition is required by MIDlet class.     */    protected void pauseApp() {    }    /**     * Responds to commands issued on CalculatorForm.     *     * @param c command object source of action     * @param d screen object containing the item the action was performed on.     */    public void commandAction(Command c, Displayable d) {        if (c == exitCmd) {            destroyApp(false);            notifyDestroyed();            return;        }        double res = 0.0;        try {            double n1 = getNumber(t1, "First");            double n2 = getNumber(t2, "Second");            switch (cg.getSelectedIndex()) {            case 0:                res = n1 + n2;                break;            case 1:                res = n1 - n2;                break;            case 2:                res = n1 * n2;                break;            case 3:                res = n1 / n2;                break;            default:            }        } catch (NumberFormatException e) {            return;        } catch (ArithmeticException e) {            alert.setString("Divide by zero.");            Display.getDisplay(this).setCurrent(alert);            return;        }        /*         * The resulted string may exceed the text max size.         * We need to correct last one then.         */        String res_str = Double.toString(res);        if (res_str.length() > tr.getMaxSize()) {            tr.setMaxSize(res_str.length());        }        tr.setString(res_str);    }    /**     * Extracts the double number from text field.     *     * @param t the text field to be used.     * @param type the string with argument number.     * @throws NumberFormatException is case of wrong input.     */    private double getNumber(TextField t, String type)        throws NumberFormatException {        String s = t.getString();        if (s.length() == 0) {            alert.setString("No " + type + " Argument");            Display.getDisplay(this).setCurrent(alert);            throw new NumberFormatException();        }        double n;        try {            n = Double.parseDouble(s);        } catch (NumberFormatException e) {            alert.setString(type + " argument is out of range.");            Display.getDisplay(this).setCurrent(alert);            throw e;        }        return n;    }} // end of class 'CalculatorMIDlet' definition