Question

我从一个例子中尝试了这段代码，但在onResume（）中得到了异常。我无法理解这是什么问题？任何人都可以为此提出建议吗？

我的代码

public class MainActivity extends Activity 
        implements LocationSource, LocationListener{

final int RQS_GooglePlayServices = 1;
private GoogleMap myMap;
TextView tvLocInfo;

LocationManager myLocationManager = null;
OnLocationChangedListener myLocationListener = null;
Criteria myCriteria;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tvLocInfo = (TextView)findViewById(R.id.locinfo);

    FragmentManager myFragmentManager = getFragmentManager();
    MapFragment myMapFragment 
        = (MapFragment)myFragmentManager.findFragmentById(R.id.map);
    myMap = myMapFragment.getMap();

    myMap.setMyLocationEnabled(true);

    myMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);

    myCriteria = new Criteria();
    myCriteria.setAccuracy(Criteria.ACCURACY_FINE);
    myLocationManager = (LocationManager)getSystemService(LOCATION_SERVICE);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case R.id.menu_legalnotices:
        String LicenseInfo = GooglePlayServicesUtil.getOpenSourceSoftwareLicenseInfo(
                getApplicationContext());
        AlertDialog.Builder LicenseDialog = new AlertDialog.Builder(MainActivity.this);
        LicenseDialog.setTitle("Legal Notices");
        LicenseDialog.setMessage(LicenseInfo);
        LicenseDialog.show();
        return true;    
    }
    return super.onOptionsItemSelected(item);   
}

@Override
protected void onResume() {
    super.onResume();

    int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(getApplicationContext());

    if (resultCode == ConnectionResult.SUCCESS){
        Toast.makeText(getApplicationContext(), 
                "isGooglePlayServicesAvailable SUCCESS", 
                Toast.LENGTH_LONG).show();

        //Register for location updates using a Criteria, and a callback on the specified looper thread.
        myLocationManager.requestLocationUpdates(
                0L,             //minTime
                0.0f,           //minDistance
                myCriteria,     //criteria
                this,           //listener
                null);          //looper

        //Replaces the location source of the my-location layer.
        myMap.setLocationSource(this);

    }else{
        GooglePlayServicesUtil.getErrorDialog(resultCode, this, RQS_GooglePlayServices);    
    }

}

@Override
protected void onPause() {
    myMap.setLocationSource(null);
    myLocationManager.removeUpdates(this);

    super.onPause();
}

@Override
public void activate(OnLocationChangedListener listener) {
    myLocationListener = listener;
}

@Override
public void deactivate() {
    myLocationListener = null;
}

@Override
public void onLocationChanged(Location location) {
    if (myLocationListener != null) {
        myLocationListener.onLocationChanged(location);

        double lat = location.getLatitude();
        double lon = location.getLongitude();

        tvLocInfo.setText(
                "lat: " + lat + "\n" +
                "lon: " + lon);
    }
}

@Override
public void onProviderDisabled(String arg0) {
    // TODO Auto-generated method stub

}

@Override
public void onProviderEnabled(String arg0) {
    // TODO Auto-generated method stub

}

@Override
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
    // TODO Auto-generated method stub

}

}

Logcat视图

02-12 10:56:34.907: W/dalvikvm(1986): threadid=1: thread exiting with uncaught exception (group=0x40e55258)
02-12 10:56:34.922: E/AndroidRuntime(1986): FATAL EXCEPTION: main
02-12 10:56:34.922: E/AndroidRuntime(1986): java.lang.RuntimeException: Unable to resume activity {com.example.androidmapsv2/com.example.androidmapsv2.MainActivity}: java.lang.IllegalArgumentException: no provider_s found for criteria
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2491)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2519)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2033)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.ActivityThread.access$600(ActivityThread.java:127)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1179)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.os.Looper.loop(Looper.java:137)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.ActivityThread.main(ActivityThread.java:4508)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at java.lang.reflect.Method.invokeNative(Native Method)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at java.lang.reflect.Method.invoke(Method.java:511)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at dalvik.system.NativeStart.main(Native Method)
02-12 10:56:34.922: E/AndroidRuntime(1986): Caused by: java.lang.IllegalArgumentException: no provider_s found for criteria
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.os.Parcel.readException(Parcel.java:1331)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.os.Parcel.readException(Parcel.java:1281)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.location.ILocationManager$Stub$Proxy.requestLocationUpdates(ILocationManager.java:671)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.location.LocationManager._requestLocationUpdates(LocationManager.java:582)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.location.LocationManager.requestLocationUpdates(LocationManager.java:563)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at com.example.androidmapsv2.MainActivity.onResume(MainActivity.java:88)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1159)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.Activity.performResume(Activity.java:4553)
02-12 10:56:34.922: E/AndroidRuntime(1986):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2481)
02-12 10:56:34.922: E/AndroidRuntime(1986):     ... 12 more

Answer 1

您应该查看Android-Developers页面，您可以在其中找到requestLocationUpdates method的声明。

public void requestLocationUpdates (long minTime, float minDistance, Criteria criteria, LocationListener listener, Looper looper)

在那里你可以看到方法抛出的异常

Throws
    IllegalArgumentException    if criteria is null
    IllegalArgumentException    if listener is null
    SecurityException   if no suitable permission is present

如果你现在看看你的代码

    myLocationManager.requestLocationUpdates(
            0L,             //minTime
            0.0f,           //minDistance
            myCriteria,     //criteria
            this,           //listener
            null);          //looper

和您的例外

E/AndroidRuntime: java.lang.RuntimeException: Unable to resume activity {...}: 
        java.lang.IllegalArgumentException: no provider_s found for criteria
                   ^^^^^^^ this                              and this  ^^^^

以及

at com.example.androidmapsv2.MainActivity.onResume(MainActivity.java:88)

您可以看到IllegalArgumentException被排在第88行。原因是criteria在调用null时为requestLocationUpdates。

criteria中OnCreate的初始化是不够的。调用OnResume后，您需要进行空检查以确认criteria已实例化。

Android Google Map Api V2中的例外情况

1 个答案: