Android Home和Back按钮使我的应用程序崩溃

Question

我是Android编程的初学者。在我的小模型应用程序中，MainActivity通过GPS引发服务生成位置。 当Location由Android Studio的Device Monitor生成时，此应用程序在虚拟设备（API 16）上运行良好。 但是，如果我按下HOME或BACK按钮，应用程序崩溃，我不知道为什么？

你可以帮帮我吗？请原谅我可怜的英文！

非常感谢

代码： MainActivity.java     包com.jacky.colbak;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.location.Location;
import android.os.Bundle;
import android.os.IBinder;
import android.widget.TextView;

public class MainActivity extends Activity implements IServListener {
    private GpsServ gpsServ;
    private boolean bound = false;
    private IServListener listener;
    private TextView latitude = null;
    private TextView longitude = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    latitude = (TextView)findViewById(R.id.vLat);
    longitude = (TextView)findViewById(R.id.vLong);
}

@Override
protected void onStart() {
    super.onStart();
    // Bind to GpsServ service
    Intent intent = new Intent(this, GpsServ.class);
    startService(intent);
}

@Override
protected void onResume() {
    super.onResume();
    listener =(IServListener) this;
    // bindService va mettre à jour bound et rentrer listener dans IServ
    Intent intent = new Intent(this, GpsServ.class);
    bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
}

@Override
protected void onPause() {
    unbindService(mConnection);
    super.onPause();
}

@Override
protected void onStop() {
    // Unbind from the service
    if (bound) {
        unbindService(mConnection);
    }
    super.onStop();
}

protected void onDestroy() {
    Intent intent = new Intent(this, GpsServ.class);
    stopService(intent);
    super.onDestroy();
}

/** Defines callbacks for service binding, passed to bindService() */
private ServiceConnection mConnection  = new ServiceConnection() {
    @Override
    public void onServiceConnected(ComponentName className, IBinder service) {
        // We've bound to LocalService, cast the IBinder and get LocalService instance
        GpsServ.LocalBinder binder = (GpsServ.LocalBinder) service;
        gpsServ = binder.getService();
        bound = true;
        ((IServ) gpsServ).addListener(listener);
     }

    @Override
    public void onServiceDisconnected(ComponentName arg0) {
        bound = false;
        ((IServ)gpsServ).delListener();
    }
};

public void refresh() {
    MainActivity.this.runOnUiThread(new Runnable() {
        public void run() {
            // Mise à jour de l'UI
            maj();
        }
    });
}

public void maj() {
    String str = Location.convert(gpsServ.dLat, Location.FORMAT_SECONDS);
    latitude.setText(str);
    str=  Location.convert(gpsServ.dLong, Location.FORMAT_SECONDS);
    longitude.setText(str);
}
}

// Voici le code du service GpsServ.java

package com.jacky.colbak;

import android.Manifest;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Binder;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.support.v4.app.ActivityCompat;
import android.widget.Toast;


public class GpsServ extends Service implements LocationListener, IServ {
    private final IBinder binder = new LocalBinder();
    private IServListener iServListener = null;
    private LocationManager locMngr;
    public double dLat, dLong;

@Override
public void onCreate() {
    Toast.makeText(getBaseContext(), "Service créé ! ",      Toast.LENGTH_SHORT).show();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    new Thread(new Runnable() {
        @Override
        public void run() {
            gpsJob();
        }
    }).run();
    return START_STICKY;
}

private void gpsJob() {
    locMngr = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        Toast.makeText(getBaseContext(), "LocationUpdates non créé (permissions refusées)! ", Toast.LENGTH_SHORT).show();
        return;
    }
    locMngr.requestLocationUpdates(LocationManager.GPS_PROVIDER, (long) 10000, (float) 10.0, this);
    Toast.makeText(getBaseContext(), "Service créé ! ", Toast.LENGTH_SHORT).show();
}

@Override
public void onDestroy() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
       return;
    }
    iServListener = null;
    locMngr.removeUpdates(this);
    locMngr = null;
    super.onDestroy();
}

// Class used for the client Binder.
public class LocalBinder extends Binder {
    GpsServ getService() {
        // Return this instance of GpsServ service so clients can call public methods
        return GpsServ.this;
    }
}

@Override
public IBinder onBind(Intent intent) {
   // TODO: Return the communication channel to the service.
   // throw new UnsupportedOperationException("Not yet implemented");
    return binder;
}
// Implementation des fonctions de LocationListener et notification au(x) listeners
@Override
public void onLocationChanged(Location location) {
    Toast.makeText(getBaseContext(), "Location Changed ", Toast.LENGTH_SHORT).show();
    dLat = location.getLatitude();
    dLong = location.getLongitude();
    if(iServListener != null){
        Toast.makeText(getBaseContext(), "Il y a un listener et on rafraichi ! ", Toast.LENGTH_SHORT).show();
        iServListener.refresh();
     }
}

@Override
public void onProviderDisabled(String provider) {
    Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
//        startActivity(intent);
}

@Override
public void onProviderEnabled(String provider) {
    Toast.makeText(getBaseContext(), "GpsServ is turned ON!! ", Toast.LENGTH_SHORT).show();
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub
    String msg = provider + " Status changed: " + status;
    Toast.makeText(getBaseContext(), msg, Toast.LENGTH_LONG).show();
}
// Implementation de de IServ
// Ajout d'un listener issu d'une vue
public void addListener(IServListener listener) {
    iServListener = listener;
}
// 

// Suppression d'un listener
public void delListener() {
    iServListener = null;
}
}


// Fichier ISev.java


package com.jacky.colbak;

/**
 * Created by Jacky on 18/04/2016.
 */
public interface IServ {
    public void addListener(IServListener listener);
    public void delListener();
}

// Fichier IServListener.java
package com.jacky.colbak;

/**
 * Created by Jacky on 14/04/2016.
 */
public interface IServListener {
    public void refresh();
}



 // File manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.jacky.colbak">

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <service
        android:name=".GpsServ"
        android:enabled="true"
        android:exported="true">
    </service>
</application>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />

</manifest>


// File activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.jacky.colbak.MainActivity">


<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Longitude"
    android:id="@+id/txtLong"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_marginTop="148dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Large Text"
    android:id="@+id/vLong"
    android:layout_alignTop="@+id/txtLong"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_marginRight="73dp"
    android:layout_marginEnd="73dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Latitude"
    android:id="@+id/tLat"
    android:layout_centerVertical="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Large Text"
    android:id="@+id/vLat"
    android:layout_alignTop="@+id/tLat"
    android:layout_alignLeft="@+id/vLong"
    android:layout_alignStart="@+id/vLong" />
</RelativeLayout>