j2me学习笔记【3】——简单的在线帮助示例

一个简单的在线帮助示例，在示例中应用到了Form，TextBox。其中TextBox是用来显示帮助信息的，TextBox上有“返回”，Form上有“帮助”，“退出”。

package mtk; import javax.microedition.lcdui.Command; import javax.microedition.lcdui.CommandListener; import javax.microedition.lcdui.Display; import javax.microedition.lcdui.Displayable; import javax.microedition.lcdui.Form; import javax.microedition.lcdui.TextBox; import javax.microedition.midlet.MIDlet; import javax.microedition.midlet.MIDletStateChangeException; public class OnlineHelp extends MIDlet implements CommandListener { private Display display; private final static Command CMD_BACK=new Command("返回",Command.BACK,1); private final static Command CMD_EXIT=new Command("退出",Command.EXIT,1); private final static Command CMD_HELP=new Command("帮助",Command.HELP,1); private Form mainForm; private TextBox helpMsg; public OnlineHelp() { display=Display.getDisplay(this); mainForm=new Form("在线帮助实例"); helpMsg=new TextBox("在线帮助","按“返回”回到上一屏幕，按“退出”退出当前应用程序",81,0); helpMsg.addCommand(CMD_BACK); helpMsg.setCommandListener(this); mainForm.addCommand(CMD_EXIT); mainForm.addCommand(CMD_HELP); mainForm.setCommandListener(this); } protected void destroyApp(boolean arg0){ } protected void pauseApp() { } protected void startApp() throws MIDletStateChangeException { display.setCurrent(mainForm); } public void commandAction(Command c, Displayable d) { if(d.equals(mainForm)){ if(c==CMD_EXIT){ destroyApp(false); notifyDestroyed(); }else if(c==CMD_HELP){ display.setCurrent(helpMsg); } }else if(d.equals(helpMsg)){ if(c==CMD_BACK){ display.setCurrent(mainForm); } } } }