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);}}}}