【J2ME】ChoiceGroup

最新推荐文章于 2021-03-22 11:41:06 发布

leinglove

最新推荐文章于 2021-03-22 11:41:06 发布

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分类专栏： J2ME 文章标签： j2me command report null class import

本文链接：https://blog.youkuaiyun.com/leinglove/article/details/5416766

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本文介绍了一个使用Java Micro Edition (MIDP) 开发的简单应用程序示例，展示了如何创建MIDlet，实现用户界面元素如ChoiceGroup的选择交互，并通过不同屏幕展示选择结果。

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package cn.edu.zucc.exp1;

import javax.microedition.lcdui.*;

import javax.microedition.midlet.*;

public class MyMidlet extends MIDlet implements CommandListener {

    static Display display;
    private static Displayable demo;
    Command exit = new Command("Exit", Command.EXIT, 1);

    public MyMidlet() {
        display = Display. getDisplay_r(this);
    }

    protected void startApp() {
        demo = new ChoiceGroupDemo(this);
        demo.addCommand(exit);
        display.setCurrent(demo);
    }

    protected void pauseApp() {
        // Do nothing
    }

    protected void destroyApp(boolean unconditional) {
        notifyDestroyed();
    }

    public void commandAction(Command c, Displayable d) {
        if (c == exit) {
            exit();
        }
    }

    public void exit() {
        destroyApp(true);
    }

public class ChoiceGroupDemo extends Form implements CommandListener {

        private Command report;
        private ChoiceGroup choices;
        private CommandListener comm;

        public ChoiceGroupDemo(CommandListener c) {
            super("Choice demo");
            comm = c;

            choices = new ChoiceGroup("How much do you pay "
                    + "for wireless services each month?",
                    Choice.EXCLUSIVE);
            choices.append("0 to 10", null);
            choices.append("11 to 20", null);
            choices.append("21 to 30", null);
            choices.append("above 30", null);
            append(choices);

report = new Command("Report", Command.SCREEN, 2);

            addCommand(report);
            setCommandListener(this);
        }

        public void commandAction(Command c, Displayable d) {
            if (c == report) {
                int index = choices. getSelectedIndex_r();
                Form form = new InfoForm("Result", this);
                form.append("You are paying ");
                form.append(choices. getString_r(index));
                form.append(" per month");
                MyMidlet.display.setCurrent(form);
            }
            comm.commandAction(c, d);
        }
    }

public class InfoForm extends Form implements CommandListener {

private Displayable prev;
private Command back;

        public InfoForm(String title, Displayable prev) {
            super(title);
            this.prev = prev;

            back = new Command("Back", Command.BACK, 1);
            addCommand(back);
            setCommandListener(this);
        }

        public void commandAction(Command c, Displayable d) {
            if (c == back) {
                MyMidlet.display.setCurrent(prev);
            }
        }
    }
}

运行结果