即時通訊嘗試獲取設備的位置到我的Android應用程序。我試圖使用android開發人員網站上概述的指南,但是每當我在手機上運行代碼時,應用程序立即停止。我的代碼是:Android應用程序停止與上次的位置檢查
public class MainActivity extends AppCompatActivity implements ConnectionCallbacks, OnConnectionFailedListener{
protected static final String TAG = "MainActivity";
protected GoogleApiClient mGoogleApiClient;
protected Location mLastLocation;
protected Double lonValue;
protected Double latValue;
protected String mLatitudeLabel;
protected String mLongitudeLabel;
protected TextView mLatitudeText;
protected TextView mLongitudeText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView lonView = (TextView) findViewById(R.id.lon);
buildGoogleApiClient();
//connect to parse backend
Parse.initialize(this, "xxxx", "xxxx");
ParseInstallation.getCurrentInstallation().saveInBackground();
Log.d("myInstallation Id", ParseInstallation.getCurrentInstallation().getInstallationId());
//get location
lonValue = mLastLocation.getLatitude();
latValue = mLastLocation.getLongitude();
//text update
}
public void openLocation(View v){
startActivity(new Intent(MainActivity.this, LocationActivity.class));
}
@Override
public void onConnected(Bundle bundle) {
//check build version on phone
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
//check that app has permission to access data
if (checkSelfPermission(android.Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED || checkSelfPermission(android.Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
//get information from location service
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
Log.d(TAG,mLatitudeLabel);
}
}
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
// Provides a simple way of getting a device's location and is well suited for
// applications that do not require a fine-grained location and that do not need location
// updates. Gets the best and most recent location currently available, which may be null
// in rare cases when a location is not available.
buildGoogleApiClient();
Toast.makeText(MainActivity.this, "Should have network", Toast.LENGTH_SHORT).show();
}
/**
* Builds a GoogleApiClient. Uses the addApi() method to request the LocationServices API.
*/
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
}
@Override
protected void onStart() {
super.onStart();
mGoogleApiClient.connect();
}
@Override
protected void onStop() {
super.onStop();
if (mGoogleApiClient.isConnected()) {
mGoogleApiClient.disconnect();
}
}
@Override
public void onConnectionFailed(ConnectionResult result) {
// Refer to the javadoc for ConnectionResult to see what error codes might be returned in
// onConnectionFailed.
Log.i(TAG, "Connection failed: ConnectionResult.getErrorCode() = " + result.getErrorCode());
}
@Override
public void onConnectionSuspended(int cause) {
// The connection to Google Play services was lost for some reason. We call connect() to
// attempt to re-establish the connection.
Log.i(TAG, "Connection suspended");
mGoogleApiClient.connect();
}
}
logcat的
02-28 18:45:08.848 4048-4048/com.worcestercomputing.ryanlambert.toiletstall E/AndroidRuntime:致命異常:主 過程: com.worcestercomputing.ryanlambert.toiletstall,PID:4048 java.lang.RuntimeException:無法啓動活動 ComponentInfo {com.worcestercomputing.ryanlambert.toiletstall/com.worcestercomputing.ryanlambert.toiletstall.MainActivity}: 顯示java.lang.NullPointerException:嘗試在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)一個空對象 參考 上調用虛擬方法 '雙android.location.Location.getLatitude()' 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 在android.app.ActivityThread.-wrap11(ActivityThread.java) 在 android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1344) 在android.os.Handler.dispatchMessage(Handler.java:102) at a ndroid.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com。 android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 引起:java.lang.NullPointerException:嘗試調用虛擬 方法'double android.location.Location.getLatitude()'null object reference at com.worcestercomputing.ryanlambert.toiletstall.MainActivity.onCreate(MainActivi ty.java:63) 在android.app.Activity.performCreate(Activity.java:6251) 在 android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 在 android.app.ActivityThread.performLaunchActivity( ActivityThread.java:2369) 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 在android.app.ActivityThread.-wrap11(ActivityThread.java) 在 android.app.ActivityThread $ H.handleMessage (ActivityThread.java:1344) at android.os.Handler.dispatchMe ssage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method。調用(Native Method) at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit。Java的:616)
請問您可以發佈logcat .. – Lal
您是否在模擬器上運行它?您必須分別傳遞緯度和經度以便在模擬器上工作。此外,在現實生活中,getLastLocation有時可能返回null(用戶可能從他購買手機的那一天起禁用了位置),因此您應該實施空檢查。 –
即時通訊在物理設備上運行。我怎麼能實現這個空檢查? (對不起,只是剛剛學習繩索) –