我目前正在做一个应用程序，系统应该自动上传用户驾驶的详细信息，然后firebase将显示该驾驶员的车辆类型等。
我目前收到一个错误，我在没有使用＆＃34;＆＃34;我使用以下代码修复它
String vehiclecat ="" ;
但现在的问题是使用此代码不会将车辆数据输出到firebase，我只是输出＆＃34;＆＃34;在firebase上
任何人都可以帮我修复它吗？
package com.example.muzza.carbon1;
public class HomePage extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener{
TextView textViewMovemnet;
EditText editTextDistance, editTextSpeed, editTextTimeInterval;
Button buttonHistory;
LocationManager locationManager;
GoogleApiClient mLocationClient;
LocationListener mListener;
String vehicle ;
String vehicleCat ;
double lat, lon;
double carbonDioxideVal;
double distance, speed;
double carbonFootprint;
double x1, x2, y1, y2, t1, t2;
double x_Diff, y_Diff, timeInterval;
double total_TimeIntervals = 0;
double total_DistanceMoved = 0;
double avg_Speed = 0;
CountDownTimer timer;
double finishTime;
String userMail;
DatabaseReference dbref;
DatabaseReference dbref_Profile;
double bicycle[] = {10, 15};
double motorcycle[] = {15, 100};
double car[] = {30, 120};
double bus[] = {25, 80};
double truck[] = {25, 40};
double metro[] = {15, 40};
//////////////
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_page);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
textViewMovemnet = (TextView) findViewById(R.id.textViewMovement);
editTextDistance = (EditText) findViewById(R.id.editTextDistance);
editTextSpeed = (EditText) findViewById(R.id.editTextSpeed);
editTextTimeInterval = (EditText) findViewById(R.id.editTextTimeInterval);
buttonHistory = (Button) findViewById(R.id.buttonHistory);
dbref = FirebaseDatabase.getInstance().getReference().child("UserTrackingData");
dbref_Profile = FirebaseDatabase.getInstance().getReference().child("UserProfileData");
//GPS Enabled ?
LocationManager locationManager;
String context = Context.LOCATION_SERVICE;
locationManager = (LocationManager) getSystemService(context);
if (!locationManager.isProviderEnabled( LocationManager.GPS_PROVIDER )) {
// Build the alert dialog
android.support.v7.app.AlertDialog.Builder builder = new android.support.v7.app.AlertDialog.Builder(this);
builder.setTitle("Location Services Not Active");
builder.setMessage("Please enable Location Services and GPS");
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialogInterface, int i) {
// Show location settings when the user acknowledges the alert dialog
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(intent);
}
});
builder.setNegativeButton("No", new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dialogInterface, int i) {
Toast.makeText(getApplicationContext(), "Cannot use app without GPS", Toast.LENGTH_SHORT).show();
}
});
Dialog alertDialog = builder.create();
alertDialog.setCanceledOnTouchOutside(false);
alertDialog.show();
}
/// =================================== ///
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
///// Retrieve user email from mainActivity
Bundle emailData = getIntent().getExtras();
if (emailData == null) {
return;
}
userMail = emailData.getString("userEMail");
TextView txtUID = (TextView) findViewById(R.id.textViewUId);
txtUID.setText(userMail);
/// End retrieve ///
}
//Network available ?
public boolean isNetworkAvailable() {
ConnectivityManager connectivityManager
= (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
return activeNetworkInfo != null && activeNetworkInfo.isConnected();
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.home_page, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
Intent i = new Intent(HomePage.this, UserProfileActivity.class);
i.putExtra("userEMail", userMail);
startActivity(i);
return true;
}
return super.onOptionsItemSelected(item);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
/*
if (id == R.id.nav_camera) {
// Handle the camera action
} else if (id == R.id.nav_gallery) {
} else if (id == R.id.nav_slideshow) {
} else if (id == R.id.nav_manage) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
*/
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
@Override
public void onConnected(@Nullable Bundle bundle) {
mListener = new LocationListener() {
@Override
public void onLocationChanged(Location location) {
lat = location.getLatitude();
lon = location.getLongitude();
if(String.valueOf(lat).isEmpty()){
lat = 0;
}
if(String.valueOf(lon).isEmpty()){
lon = 0;
}
// Toast.makeText(HomePage.this, "Location: " + location.getLatitude() + " - " + location.getLongitude(), Toast.LENGTH_SHORT).show();
}
};
LocationRequest request = LocationRequest.create();
request.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
request.setInterval(4000);
request.setFastestInterval(1000);
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
else {
LocationServices.FusedLocationApi.requestLocationUpdates(mLocationClient, request, mListener);
}
}
@Override
public void onConnectionSuspended(int i) {
return;
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
return;
}
@Override
protected void onPause() {
super.onPause();
LocationServices.FusedLocationApi.removeLocationUpdates(mLocationClient, mListener);
}
@Override
protected void onStart() {
super.onStart();
firebaseRead(); // call to fetch fm db
}
//Firebase Read//
public void firebaseRead(){
dbref_Profile.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String emailAdd = ds.child("email").getValue(String.class);
// int userAge = Integer.parseInt(ds.child("age").getValue(String.class));
String fname = ds.child("firstname").getValue(String.class);
String lname = ds.child("lastname").getValue(String.class);
String vehicleType = ds.child("vehicle").getValue(String.class);
String vehCat = ds.child("vehicleCateg").getValue(String.class);
/* Toast.makeText(HistoryActivity.this, emailAdd + " - " + String.valueOf(avgSpeed) + " - " + String.valueOf(totalDist) + " - " +
String.valueOf(totalTime) + " - " + currDate, Toast.LENGTH_SHORT).show(); */
if(emailAdd.equals(userMail)){
//String listStr = emailAdd + "|" + currDate + "|" + totalDist + "|" + avgSpeed + "|" + totalTime;
// userDataArr.add(listStr);
vehicle = vehicleType;
vehicleCat = vehCat;
// Toast.makeText(HomePage.this, vehicle + " - " + vehicleCat, Toast.LENGTH_SHORT).show();
}
}//
}
@Override
public void onCancelled(DatabaseError databaseError) {
return;
}
});
} // End firebaseRead
@Override
protected void onResume() {
super.onResume();
/// Location
mLocationClient = new GoogleApiClient.Builder(this)
.addApi(LocationServices.API)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.build();
mLocationClient.connect();
/////////
// Start timer
timer = new CountDownTimer(6000, 1000) {
public void onTick(long millisUntilFinished) {
if(((millisUntilFinished/1000) == 4)){
x1 = lat;
y1 = lon;
t1 = millisUntilFinished/1000;
}
if(((millisUntilFinished/1000) == 1)){
x2 = lat;
y2 = lon;
t2 = millisUntilFinished/1000;
//timeInterval = t2 - t1;
BigDecimal bd1 = new BigDecimal(x1);
bd1 = bd1.round(new MathContext(7));
x1 = bd1.doubleValue();
BigDecimal bd2 = new BigDecimal(x2);
bd2 = bd2.round(new MathContext(7));
x2 = bd2.doubleValue();
BigDecimal bd3 = new BigDecimal(y1);
bd3 = bd3.round(new MathContext(7));
y1 = bd3.doubleValue();
BigDecimal bd4 = new BigDecimal(y2);
bd4 = bd4.round(new MathContext(7));
y2 = bd4.doubleValue();
x_Diff = Math.abs(x2) - Math.abs(x1);
x_Diff = Math.abs(x_Diff);
y_Diff = Math.abs(y2) - Math.abs(y1);
y_Diff = Math.abs(y_Diff);
// Toast.makeText(getApplicationContext(), "x_Diff: " + x_Diff + "; y-diff: " + y_Diff, Toast.LENGTH_SHORT).show();
// User Vehicle info
// CAR
if(vehicle.equals("Car") && vehicleCat.equals("Small")){
carbonDioxideVal = 0.14545;
}
if(vehicle.equals("Car") && vehicleCat.equals("Medium")){
carbonDioxideVal = 0.1738;
}
if(vehicle.equals("Car") && vehicleCat.equals("Average")){
carbonDioxideVal = 0.17887;
}
if(vehicle.equals("Car") && vehicleCat.equals("Large")){
carbonDioxideVal = 0.21834;
}
// END CAR /////////////
// Van //
if(vehicle.equals("Van") && vehicleCat.equals("Small")){
carbonDioxideVal = 0.14545;
}
if(vehicle.equals("Van") && vehicleCat.equals("Medium")){
carbonDioxideVal = 0.1738;
}
if(vehicle.equals("Van") && vehicleCat.equals("Average")){
carbonDioxideVal = 0.17887;
}
if(vehicle.equals("Van") && vehicleCat.equals("Large")){
carbonDioxideVal = 0.21834;
}
// END Van ////////////////////
// Motorbike //
if(vehicle.equals("Motorbike") && vehicleCat.equals("Small")){
carbonDioxideVal = 0.08474;
}
if(vehicle.equals("Motorbike") && vehicleCat.equals("Medium")){
carbonDioxideVal = 0.10323;
}
if(vehicle.equals("Motorbike") && vehicleCat.equals("Average")){
carbonDioxideVal = 0.11662;
}
if(vehicle.equals("Motorbike") && vehicleCat.equals("Large")){
carbonDioxideVal = 0.13542;
}
// END Motorbike //////////////////
// End User Vehicle info
distance = Math.sqrt(Math.pow((x2 - x1),2) + Math.pow((y2 - y1), 2));
carbonFootprint = distance * carbonDioxideVal;
speed = distance / 3;
// Public transport
if((speed >= 4.5) && (speed <= 8)){
vehicle = "Bus";
vehicleCat = "Long vehicle";
}
if((speed >= 8.5) && (speed <= 12.5)){
vehicle = "Metro";
vehicleCat = "Long vehicle";
}
// End Public transport
timeInterval = t2 - t1;
timeInterval = Math.abs(timeInterval);
editTextDistance.setText(String.valueOf(distance));
editTextSpeed.setText(String.valueOf(speed));
editTextTimeInterval.setText(String.valueOf(timeInterval));
if((speed == 0.0 || speed < 0.00005)){
//// Current time ////
DateFormat df = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
Date today = Calendar.getInstance().getTime();
String reportDate = df.format(today);
///
textViewMovemnet.setText("still");
avg_Speed = total_DistanceMoved / total_TimeIntervals;
UserTrackData userData = new UserTrackData(userMail, reportDate, String.valueOf(total_DistanceMoved), String.valueOf(total_TimeIntervals), String.valueOf(avg_Speed), String.valueOf(carbonFootprint), vehicle, vehicleCat);
if(String.valueOf(total_DistanceMoved).equals("0.0") || String.valueOf(total_TimeIntervals).equals("0.0") || String.valueOf(avg_Speed).equals("NaN")){
return;
}
dbref.push().setValue(userData);
/* if
(locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER) ||
!userMail.isEmpty() || !reportDate.isEmpty()
||
!String.valueOf(total_DistanceMoved).isEmpty() ||
!String.valueOf(total_TimeIntervals).isEmpty() ||
!String.valueOf(avg_Speed).isEmpty() ||
!String.valueOf(carbonFootprint).isEmpty() || !vehicle.isEmpty() ||
!vehicleCat.isEmpty()){
dbref.push().setValue(userData);
}
else {
return;
} */
// Toast.makeText(HomePage.this, "final: " +
total_DistanceMoved + " ; " + total_TimeIntervals + " ; " + avg_Speed,
Toast.LENGTH_SHORT).show();
avg_Speed = total_DistanceMoved = total_TimeIntervals =
0;
}
else {
textViewMovemnet.setText("moving");
total_DistanceMoved += distance;
total_TimeIntervals += timeInterval;
}
}
finishTime = (millisUntilFinished/1000);
}
public void onFinish() {
//Toast.makeText(getApplicationContext(), "Receive done" +
finishTime, Toast.LENGTH_SHORT).show();
this.start();
}
}.start();
Toast.makeText(getApplicationContext(), "Tracking started", Toast.LENGTH_SHORT).show();
}
public void viewHistory(View view){
Intent i = new Intent(HomePage.this, HistoryActivity.class);
i.putExtra("userEMailAddr", userMail);
startActivity(i);
}
}
我在Android工作室遇到的错误是
E/UncaughtException: java.lang.NullPointerException: Attempt to invoke
virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null
object reference
at com.example.muzza.carbon1.HomePage$5.onTick(HomePage.java:447)
at android.os.CountDownTimer$1.handleMessage(CountDownTimer.java:133)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5601)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:964)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:759)
我通过添加更改以下行来修复错误
String vehicle ; -------------- String vehicle = "" ;
String vehicleCat ; --------------- String vehicleCat="";
但现在的问题是我的firebase没有显示我想要的数据
在我保存firebase之前，我得到了这个 As can be seen, vehicle and vehiclecategory was available on firebase 现在我改变了线路字符串vehiclecat和String cat后，现在我无法在firebase上获得这样的数据
No data of vehicle and vehicle category
任何人都可以帮我解决这个问题吗？
这是另一个java文件UserTrackData.java
package com.example.muzza.carbon1;
/**
* Created by muzza on 20-Mar-18.
*/
public class UserTrackData {
String email;
String currentDate;
String totalDistance;
String totalTime;
String avgSpeed;
String carbonFootprint;
String vahicle;
String vehicleCateg;
public UserTrackData(String email, String currentDate, String totalDistance, String totalTime, String avgSpeed, String carbonFootprint, String vahicle, String vehicleCateg) {
this.email = email;
this.currentDate = currentDate;
this.totalDistance = totalDistance;
this.totalTime = totalTime;
this.avgSpeed = avgSpeed;
this.carbonFootprint = carbonFootprint;
this.vahicle = vahicle;
this.vehicleCateg = vehicleCateg;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getCurrentDate() {
return currentDate;
}
public void setCurrentDate(String currentDate) {
this.currentDate = currentDate;
}
public String getTotalDistance() {
return totalDistance;
}
public void setTotalDistance(String totalDistance) {
this.totalDistance = totalDistance;
}
public String getTotalTime() {
return totalTime;
}
public void setTotalTime(String totalTime) {
this.totalTime = totalTime;
}
public String getAvgSpeed() {
return avgSpeed;
}
public void setAvgSpeed(String avgSpeed) {
this.avgSpeed = avgSpeed;
}
public String getCarbonFootprint() {
return carbonFootprint;
}
public void setCarbonFootprint(String carbonFootprint) {
this.carbonFootprint = carbonFootprint;
}
public String getVahicle() {
return vahicle;
}
public void setVahicle(String vahicle) {
this.vahicle = vahicle;
}
public String getVehicleCateg() {
return vehicleCateg;
}
public void setVehicleCateg(String vehicleCateg) {
this.vehicleCateg = vehicleCateg;
}
}