protected void destroyApp(boolean unconditional) {
}
protected void pauseApp() {
}
public void commandAction(Command c, Displayable d) {
//注意这里是如何实现CommandListener这个接口的！
if (d.equals(mainList)) {
if (c == List.SELECT_COMMAND) {
if (d.equals(mainList)) {
switch (((List)d).getSelectedIndex()) {
case 0:
display.setCurrent(exclusiveList);
break;
case 1:
display.setCurrent(implicitList);
break;
case 2:
display.setCurrent(multipleList);
