用Alert创建确认对话框

来源：Nokia 作者：Nokia 出处：巧巧读书 2008-03-06 进入讨论组

关键词：
java

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下面的代码介绍了如何使用Alert来创建一个确认对话框。

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class ConfirmationMIDlet extends MIDlet implements CommandListener {
    private Form form;
    private Alert alert;
    private Command exitCommand;

    public void startApp() {
        form = new Form("ConfirmationMIDlet");
exitCommand = new Command("Exit", Command.EXIT, 1);
form.setCommandListener(this);
form.addCommand(exitCommand);
        Display.getDisplay(this).setCurrent(form);
    }

    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional) {
    }

    public void commandAction (Command c, Displayable d) {
        if (c == exitCommand) {
            showConfirmation("Confirmation", "Do you really want to exit?");
        }
    }

    private void closeAlert() {
        Display.getDisplay(this).setCurrent(form);
        alert = null;
    }

    protected void showConfirmation(String title, String text) {
        alert = new Alert(title, text, null, AlertType.CONFIRMATION);
        alert.addCommand(new Command ("Yes", Command.OK, 1));
        alert.addCommand(new Command("No", Command.CANCEL, 1));
        alert.setCommandListener(new CommandListener() {
            public void commandAction(Command c, Displayable d) {
                if (c.getLabel().equals("Yes")) { notifyDestroyed();
                }
                if (c.getLabel().equals("No")) {
                    closeAlert();
                }
            }
        });
        Display.getDisplay(this).setCurrent(alert, form);
    }
}