我在模拟器中部署代码后创建了一个使用GPS获取我的位置坐标的应用程序我遇到上述错误并附带解释 -
uncaught exception:pushmodalscreen called by a non-event thread
我无法弄清楚什么是错的。
/**
* GPSDemo.java
*
* Copyright © 1998-2011 Research In Motion Ltd.
*
* Note: For the sake of simplicity, this sample application may not leverage
* resource bundles and resource strings. However, it is STRONGLY recommended
* that application developers make use of the localization features available
* within the BlackBerry development platform to ensure a seamless application
* experience across a variety of languages and geographies. For more information
* on localizing your application, please refer to the BlackBerry Java Development
* Environment Development Guide associated with this release.
*/
package com.gps;
import java.util.*;
import javax.microedition.location.*;
import net.rim.device.api.command.*;
import net.rim.device.api.gps.*;
import net.rim.device.api.system.*;
import net.rim.device.api.ui.*;
import net.rim.device.api.ui.component.*;
import net.rim.device.api.ui.container.*;
import net.rim.device.api.util.*;
import net.rim.blackberry.api.invoke.*;
import net.rim.blackberry.api.maps.*;
import net.rim.blackberry.api.menuitem.*;
/**
* This application acts as a simple travel computer, recording route
* coordinates, speed and altitude. Recording begins as soon as the
* application is invoked.
*/
public class GPSScreen extends UiApplication
{
// Represents the number of updates over which altitude is calculated, in seconds
private static final int GRADE_INTERVAL = 5;
private static final long ID = 0x5d459971bb15ae7aL;
// Represents period of the position query, in seconds
private static int _interval = 1;
private double _latitude;
private double _longitude;
private LocationProvider _locationProvider;
private GPSDemoScreen _screen;
private MapView _mapview = new MapView();
/**
* Entry point for application
*
* @param args Command line arguments (not used)
*/
public static void main(String[] args)
{
// Create a new instance of the application and make the currently
// running thread the application's event dispatch thread.
new GPSScreen().enterEventDispatcher();
}
/**
* Create a new GPSDemo object
*/
public GPSScreen()
{
_screen = new GPSDemoScreen();
_screen.setTitle("GPS Demo");
// Attempt to start the location listening thread
if(startLocationUpdate())
{
_screen.setState(_locationProvider.getState());
}
// Render the screen
pushScreen(_screen);
}
/**
* Invokes the Location API with Standalone criteria
*
* @return True if the <code>LocationProvider</code> was successfully started, false otherwise
*/
private boolean startLocationUpdate()
{
boolean returnValue = false;
if(!(GPSInfo.getDefaultGPSMode() == GPSInfo.GPS_MODE_NONE))
{
try
{
Criteria criteria = new Criteria();
criteria.setCostAllowed(false);
_locationProvider = LocationProvider.getInstance(criteria);
if(_locationProvider != null)
{
/*
* Only a single listener can be associated with a provider,
* and unsetting it involves the same call but with null.
* Therefore, there is no need to cache the listener
* instance request an update every second.
*/
_locationProvider.setLocationListener(new LocationListenerImpl(), _interval, -1, -1);
returnValue = true;
}
else
{
invokeLater(new Runnable()
{
public void run()
{
Dialog.alert("Failed to obtain a location provider, exiting...");
System.exit(0);
}
});
}
}
catch(final LocationException le)
{
invokeLater(new Runnable()
{
public void run()
{
Dialog.alert("Failed to instantiate LocationProvider object, exiting..." + le.toString());
System.exit(0);
}
});
}
}
else
{
invokeLater(new Runnable()
{
public void run()
{
Dialog.alert("GPS is not supported on this device, exiting...");
System.exit(0);
}
});
}
return true;
}
/**
* Implementation of the LocationListener interface. Listens for updates to
* the device location and displays the results.
*/
private class LocationListenerImpl implements LocationListener
{
/**
* @see javax.microedition.location.LocationListener#locationUpdated(LocationProvider,Location)
*/
public void locationUpdated(LocationProvider provider, Location location)
{
if(location.isValid())
{
_longitude = location.getQualifiedCoordinates().getLongitude();
_latitude = location.getQualifiedCoordinates().getLatitude();
_mapview.setZoom(Integer.parseInt("0.1"));
try
{
int latitude = (int) (100000 * _latitude);
int longitude = (int) (100000 * _longitude);
if (latitude > 9000000 || latitude < -9000000 || longitude >= 18000000 || longitude < -18000000)
{
throw new IllegalArgumentException ();
}
_mapview.setLatitude(latitude);
_mapview.setLongitude(longitude);
// Invoke BlackBerry Maps application with provided MapView object.
Invoke.invokeApplication(Invoke.APP_TYPE_MAPS, new MapsArguments(_mapview));
}
catch(RuntimeException re)
{
// An exception is thrown when any of the following occur :
// Latitude is invalid : Valid range: [-90, 90]
// Longitude is invalid : Valid range: [-180, 180)
// Minus sign between 2 numbers.
Dialog.alert("Temporary Unavailable Service");
}
}
}
/**
* @see javax.microedition.location.LocationListener#providerStateChanged(LocationProvider, int)
*/
public void providerStateChanged(LocationProvider provider, int newState)
{
if(newState == LocationProvider.TEMPORARILY_UNAVAILABLE)
{
provider.reset();
}
_screen.setState(newState);
}
}
/**
* The main screen to display the current GPS information
*/
private final class GPSDemoScreen extends MainScreen
{
TextField _statusTextField;
/**
* Create a new GPSDemoScreen object
*/
GPSDemoScreen()
{
// Initialize UI
_statusTextField = new TextField(Field.NON_FOCUSABLE);
}
/**
* Display the state of the GPS service
*
* @param newState The state to display
*/
public void setState(final int newState)
{
UiApplication.getUiApplication().invokeLater(new Runnable()
{
/**
* @see java.lang.Runnable#run()
*/
public void run()
{
switch(newState)
{
case LocationProvider.AVAILABLE:
_statusTextField.setText("Available");
break;
case LocationProvider.OUT_OF_SERVICE:
_statusTextField.setText("Out of Service");
break;
case LocationProvider.TEMPORARILY_UNAVAILABLE:
_statusTextField.setText("Temporarily Unavailable");
break;
}
}
});
}
/**
* @see net.rim.device.api.ui.Screen#close()
*/
public void close()
{
if(_locationProvider != null)
{
_locationProvider.reset();
_locationProvider.setLocationListener(null, -1, -1, -1);
}
super.close();
}
}
}
答案 0 :(得分：0)
我在事件线程之外使用Dialog.alert（）时看到了这个错误。查看代码，我看到LocationListenerImpl.locationUpdated假定它在事件线程上运行。如果不是，UI更新代码将抛出异常，然后您的异常处理程序将尝试显示一个对话框，这也将失败。