android - 在android应用程序中使用BroadCastReceiver获取经纬度？

Question

Hai 是 android 应用程序的新手，我正在尝试使用广播接收器获取纬度和经度。但是我的应用程序正在强制关闭。我不知道为什么会发生这种情况。任何人都可以纠正我的错误。

        @Override
        public void onClick(View v) 
        {
             locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
             // Define the criteria how to select the locatioin provider -> use
             // default
             Criteria criteria = new Criteria();

         provider = locationManager.getBestProvider(criteria, false);
         Location location = locationManager.getLastKnownLocation(provider);

         // Initialize the location fields
         if (location != null) {
            System.out.println("Provider " + provider + " has been selected.");
            float lat = (float) (location.getLatitude());
            float lng = (float) (location.getLongitude());
            latituteField.setText(String.valueOf(lat));
            longitudeField.setText(String.valueOf(lng));

         } else {
            latituteField.setText("provider not available");
            longitudeField.setText("provider not available");
         }
            registerReceiver(receiver,new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
        }
    });

        private class ConnectivityReceiver extends BroadcastReceiver{

            @Override
            public void onReceive(Context context, Intent intent) {
                    NetworkInfo info = intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO);

                    if(null != info)
                    {
                            String state = getNetworkStateString(info.getState());
                            String stateString = info.toString().replace(',', '\n');
                            if(state.equals("Connected")){
                                result();

                            }

                    }
            }

}
    @Override
    protected void onResume() {
        super.onResume();
        //locationManager.requestLocationUpdates(provider,1000, 1, this);
        locationManager.requestLocationUpdates(
                provider, 
                MINIMUM_TIME_BETWEEN_UPDATES, 
                MINIMUM_DISTANCE_CHANGE_FOR_UPDATES,
                this
        );
    }

    /* Remove the locationlistener updates when Activity is paused */
    @Override
    protected void onPause() {
        super.onPause();
        locationManager.removeUpdates(this);
    }

    @Override
    public void onLocationChanged(Location location) {
        // TODO Auto-generated method stub
        float lat = (float) (location.getLatitude());
        float lng = (float) (location.getLongitude());
        longitudeField.setText(String.valueOf(lng));
    }

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

    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub
        Toast.makeText(this, "Enabled new provider " + provider,
                Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub
        Toast.makeText(this, "Disenabled provider " + provider,
                Toast.LENGTH_SHORT).show();

    }
    protected void Display(Cursor c) {
        Toast.makeText(this, "rowid: " + c.getString(0) + "\n" +
         "Latitude: " + c.getString(1) + "\n" + "Longitude: " + c.getString(2) + "\n" +
         Toast.LENGTH_LONG, 0).show();    
    }

    **updata Logcat Error Message**



   "01-06 12:08:27.376: ERROR/AndroidRuntime(9725): java.lang.RuntimeException: Unable to resume activity {com.varma.samples.conntest/com.varma.samples.conntest.MainActivity}: java.lang.NullPointerException
    01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at  android.app.ActivityThread.performResumeActivity(ActivityThread.java:3133)
    01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3148)
    01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2689)
    01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.app.ActivityThread.access$2300(ActivityThread.java:126)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2038)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.os.Handler.dispatchMessage(Handler.java:99)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.os.Looper.loop(Looper.java:123)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.app.ActivityThread.main(ActivityThread.java:4632)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at java.lang.reflect.Method.invokeNative(Native Method)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at java.lang.reflect.Method.invoke(Method.java:521)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:871)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:629)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at dalvik.system.NativeStart.main(Native Method)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725): Caused by: java.lang.NullPointerException
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at com.varma.samples.conntest.MainActivity.onResume(MainActivity.java:158)
     01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1149)
    01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.app.Activity.performResume(Activity.java:3823)
  01-06 12:08:27.376: ERROR/AndroidRuntime(9725):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3123)
"

我的 list 文件*更新*

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.varma.samples.conntest"
  android:versionCode="1"
  android:versionName="1.0">
<uses-sdk android:minSdkVersion="8" />

<application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name=".MainActivity"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

</application>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
      <uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
 <uses-permission android:name="android.permission.INTERNET"/>
 <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" />     </manifest>

Answer 1

移动线

locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

从onclick方法到oncreate方法