package ora.ch4;import javax.microedition.lcdui.Command;import javax.microedition.lcdui.CommandListener;import javax.microedition.lcdui.Displayable;import javax.microedition.lcdui.*;public class TextBox2MIDlet extends TextBoxMIDlet implements CommandListener {    // Exit command    private static final Command EXIT_COMMAND =                         new Command("Exit", Command.EXIT, 0);        // OK command    private static final Command OK_COMMAND =                        new Command("OK", Command.OK, 0);        // Clear text box content    private static final Command CLEAR_COMMAND =                        new Command("Clear", Command.SCREEN, 1);        // Reverse the content of the text box    private static final Command REVERSE_COMMAND =                        new Command("Reverse", Command.SCREEN, 1);    protected void startApp() {        boolean firstTime = !started;        super.startApp();                // If this is the first execution        // of startApp, install commands        if (firstTime) {            textBox.addCommand(OK_COMMAND);                        textBox.addCommand(EXIT_COMMAND);            textBox.addCommand(CLEAR_COMMAND);                        textBox.addCommand(REVERSE_COMMAND);                        textBox.setCommandListener(this);        }    }        // Command implementations.    public void commandAction(Command c, Displayable d) {        if (c == EXIT_COMMAND) {            destroyApp(true);            notifyDestroyed();        } else if (c == OK_COMMAND) {            System.out.println("OK pressed");        } else if (c == CLEAR_COMMAND) {            textBox.setString(null);        } else if (c == REVERSE_COMMAND) {            String str = textBox.getString();            if (str != null) {                StringBuffer sb = new StringBuffer(str);                textBox.setString(sb.reverse().toString());            }                    }    }    }