Alert中添加Gauge对象

程序：

Alert alert=new Alert(alertString);
    gauge= new Gauge("gauge", false, 10, 0);
    int value=gauge.getValue();
    gauge.setValue(0);
    alert.setTimeout(36000);
    alert.setIndicator(gauge);
    display.setCurrent(alert);

 

当运行以上代码时，报以下错误：

java.lang.IllegalArgumentException: Gauge in wrong state
 at javax.microedition.lcdui.Alert.setIndicator(+45)
 at p_c_03.Medlet6.commandAction(+161)
 at javax.microedition.lcdui.List.callKeyPressed(+80)
 at javax.microedition.lcdui.Display$DisplayAccessor.keyEvent(+198)
 at javax.microedition.lcdui.Display$DisplayManagerImpl.keyEvent(+11)
 at com.sun.midp.lcdui.DefaultEventHandler.keyEvent(+127)
 at com.sun.midp.lcdui.AutomatedEventHandler.keyEvent(+210)
 at com.sun.midp.lcdui.DefaultEventHandler$QueuedEventHandler.handleVmEvent(+114)
 at com.sun.midp.lcdui.DefaultEventHandler$QueuedEventHandler.run(+57)

 

原因是因为：gauge= new Gauge("gauge", false, 10, 0);中的第一个参数应该为null

if you add a Gauge to an Alert use setIndicator method, set label string of the Gauge to null.

如果你通过调用alert的方法setIndicator（）方法去添加一个Gauge对象时，要把参数label的值设置为null