I am creating a GPS tracking application, I am in beginning stage, I have traced the latitude and Longitude using LocationManager, now the next thing I want to do is to store all the data in database, I have created Adapter class and am calling it from MainActivity but am getting NullPointerException while binding the Context and Opening the database, please look at my Logcat details and please suggest me a solution.
I am getting the error message near
dbAdapter = new LocationDbAdapter(this);
dbAdapter.open();
Error Log :
android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:234)
android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:149)
om.example.androidtrackingapplication.LocationDbAdapter.open(LocationDbAdapter.java:78)
I have attached Complete Logcat file below please check and let me know where I am going Wrong.
I am sending the Location to the Adapter Class where it will fetch the values and store in the table .
I am calling database instance when I get the locationupdate, When I click on Locate Button which will calls LocationManager to get Location Update (This the point where my application crashes).
LocationDbAdapter.java
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.location.Location;
import android.util.Log;
public class LocationDbAdapter {
public static final String KEY_NAME = "name";
public static final String KEY_LATITUDE = "latitude";
public static final String KEY_LONGITUDE = "longitude";
public static final String KEY_ACCURACY = "accuracy";
public static final String KEY_TIME = "time";
public static final String KEY_ROWID = "_id";
private static final String TAG = "LocationDbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
private static final String DATABASE_CREATE =
"create table locations (_id integer primary key autoincrement, "
+ "name text not null, latitude real not null, longitude real not null, accuracy integer not null, time integer not null);";
private static final String DATABASE_NAME = "data";
private static final String DATABASE_TABLE = "locations";
private static final int DATABASE_VERSION = 4;
private final Context mCtx;
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DATABASE_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.i(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS locations");
onCreate(db);
}
}
/**
* Constructor - takes the context to allow the database to be
* opened/created
*
* @param ctx the Context within which to work
*/
public LocationDbAdapter(Context ctx) {
this.mCtx = ctx;
}
/**
* Open the notes database. If it cannot be opened, try to create a new
* instance of the database. If it cannot be created, throw an exception to
* signal the failure
*
* @return this (self reference, allowing this to be chained in an
* initialization call)
* @throws SQLException if the database could be neither opened or created
*/
public LocationDbAdapter open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
/**
* Add new location. If the location is
* successfully created return the new rowId, otherwise return
* a -1 to indicate failure.
*
* @param location
* @return rowId or -1 if failed
*/
public long addLocation(Location location) {
Log.i(TAG, "Writing new location:"+location.toString());
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_NAME, location.getProvider());
contentValues.put(KEY_LATITUDE, location.getLatitude());
contentValues.put(KEY_LONGITUDE, location.getLongitude());
contentValues.put(KEY_ACCURACY, location.getAccuracy());
contentValues.put(KEY_TIME, location.getTime());
return mDb.insert(DATABASE_TABLE, null, contentValues);
}
public int clearDatabase() {
Log.i(TAG, "clearDatabase()");
return mDb.delete(DATABASE_TABLE, null, null);
}
public Cursor fetchAllLocations() {
return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_NAME, KEY_LATITUDE, KEY_LONGITUDE, KEY_ACCURACY,
KEY_TIME}, null, null, null, null, null);
}
}
MainActivity.java
package com.example.androidtrackingapplication;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Timer;
import java.util.TimerTask;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.Activity;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.location.GpsStatus;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.BatteryManager;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.os.IBinder;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity
{
LocationManager mlocManager ;
LocationListener mlocListener ;
Location loc;
double lat;
double longitude;
EditText Lat;
EditText Long,battery,hitTime,intervalTime;
int level = -1;
static int i;
Button Send,Reset,Locate,Close;
private LocationDbAdapter dbAdapter;
Timer t;
protected CountDownTimer waitTimer;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Lat= (EditText) findViewById(R.id.editText1);
Long=(EditText) findViewById(R.id.editText2);
//hitTime= (EditText) findViewById(R.id.editText3);
//intervalTime=(EditText) findViewById(R.id.editText4);
Locate=(Button) findViewById(R.id.button1);
Send= (Button) findViewById(R.id.button2);
Close=(Button) findViewById(R.id.button3);
Locate.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// String hit=hitTime.getText().toString();
// int hit1= Integer.parseInt(hit);
// System.out.println("Hit"+hit1);
Send.setEnabled(false);
Lat.setText(" ");
Long.setText(" ");
/* Enable the Gps */
Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
intent.putExtra("enabled", true);
sendBroadcast(intent);
waitTimer = new CountDownTimer(60000,1000) {
public void onTick(long millisUntilFinished) {
i = i+1;
System.out.println("IN:"+i);
mlocManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
mlocListener = new MyLocationListener();
loc = mlocManager.getLastKnownLocation( LocationManager.GPS_PROVIDER);
// mlocManager.requestLocationUpdates( LocationManager.GPS_PROVIDER,300000, 0, mlocListener);
//mlocManager.requestSingleUpdate(LocationManager.GPS_PROVIDER,mlocListener, null);
mlocManager.requestSingleUpdate(LocationManager.GPS_PROVIDER,mlocListener, null);
}
public void onFinish() {
System.out.println("Location not found");
Toast.makeText(getApplicationContext(), "Location Not Found ", Toast.LENGTH_LONG).show();
if(mlocManager!=null)
{
}
Lat.setText(" ");
Long.setText(" ");
if(loc!=null)
{
Lat.setText(String.valueOf(loc.getLatitude()));
Long.setText(String.valueOf(loc.getLongitude()));
}
Toast.makeText(getApplicationContext(), "Last Location ",Toast.LENGTH_LONG).show();
Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
intent.putExtra("enabled", false);
sendBroadcast(intent);
}
}.start();
}
});
Send.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// String lat1="15.012345";
// String longitude1="75.012345";
HttpClient httpClient = new DefaultHttpClient();
String postURL = "";
postURL = "http://bb.trackfleet.biz/android_gps/lat_long.php?lat="+lat+"&long="+longitude;
HttpPost httpPost = new HttpPost(postURL);
HttpResponse httpResponse = null;
try
{
Toast.makeText(getApplicationContext(),"send", Toast.LENGTH_SHORT).show();
httpResponse = httpClient.execute(httpPost);
String str = inputStreamToString(httpResponse.getEntity().getContent()).toString();
Toast.makeText(getApplicationContext(), str, Toast.LENGTH_SHORT).show();
}
catch(Exception ex)
{
Toast.makeText(getApplicationContext(),"error", Toast.LENGTH_SHORT).show();
}
}
});
Close.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if(mlocManager!=null)
{
mlocManager.removeUpdates(mlocListener);
mlocManager=null;
}
Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
intent.putExtra("enabled", false);
sendBroadcast(intent);
finish();
}
});
}
private StringBuilder inputStreamToString(InputStream is) {
String line = "";
StringBuilder total = new StringBuilder();
// Wrap a BufferedReader around the InputStream
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
// Read response until the end
try {
while ((line = rd.readLine()) != null) {
total.append(line);
}
} catch (IOException e) {
e.printStackTrace();
}
// Return full string
return total;
}
MyLocationListener Service
public class MyLocationListener extends Service implements LocationListener
{
@Override
public void onCreate() {
dbAdapter = new LocationDbAdapter(this);
dbAdapter.open();
}
@Override
public void onLocationChanged(Location loc)
{
if(loc!=null)
{
dbAdapter = new LocationDbAdapter(this);
dbAdapter.open();
long id=dbAdapter.addLocation(loc);
Toast.makeText(getApplicationContext(), "Added Data Sucessfully " +id ,Toast.LENGTH_SHORT).show();
}
lat=loc.getLatitude();
longitude=loc.getLongitude();
waitTimer.cancel();
String Text = "My current location is: " +
"Latitud = " + loc.getLatitude() +
"Longitud = " + loc.getLongitude();
Lat.setText(String.valueOf(lat));
Long.setText(String.valueOf(longitude));
if((Lat.getText()!=null) && (Long.getText()!=null))
{
Send.setEnabled(true);
Send.performClick();
}
}
@Override
public void onProviderDisabled(String provider)
{
Toast.makeText( getApplicationContext(),"Gps Disabled Pls Enable It",Toast.LENGTH_SHORT ).show();
startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
}
@Override
public void onProviderEnabled(String provider)
{
Toast.makeText( getApplicationContext(),"Gps Enabled",Toast.LENGTH_SHORT).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras)
{
}
@Override
public void onDestroy()
{
super.onDestroy();
dbAdapter.close();
mlocManager.removeUpdates(this);
}
@Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return null;
}
}
}
