User location sender app crashes when button is pushed

Question

I have developed an app that sends the user's location via SMS. When I starting building it there were no errors, but when it is being tested with an actual phone it crashes ... It would not open.

public class MainActivity extends AppCompatActivity {
EditText phone;
Button emergency;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    phone= (EditText) findViewById(R.id.number);

    emergency= (Button) findViewById(R.id.emergency);

    emergency.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            GPStracker g = new GPStracker(getApplicationContext());
            Location l = g.getLocation();
            if (l != null) {
                double lat = l.getLatitude();
                double lon = l.getLongitude();
                String message = "http://maps.google.com/maps?saddr=" + lat + "," + lon;
                String number = "number";
                SmsManager smsManager = SmsManager.getDefault();
                StringBuffer smsBody = new StringBuffer();
                smsBody.append(Uri.parse(message));
                android.telephony.SmsManager.getDefault().sendTextMessage(number, null, smsBody.toString(), null, null);
            }
        }
    });
}

AND ALSO HERE IS MY CLASS FOR GPS TRACKING

public class GPStracker implements LocationListener {
    Context context;
    public GPStracker(Context c){
        context = c;
    }

    public Location getLocation(){

        LocationManager lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
        boolean isGPSEnabled = lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
        if (isGPSEnabled){
            lm.requestLocationUpdates(LocationManager.GPS_PROVIDER,5000,10,this);
            Location l = lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
            return l;
        }else{
            Toast.makeText(context,"Please enable GPS", Toast.LENGTH_LONG).show();
        }
        return null;
    }

    @Override
    public void onLocationChanged(Location location) {

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {

    }

    @Override
    public void onProviderEnabled(String provider) {Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
        intent.putExtra("enabled", true);

    }

    @Override
    public void onProviderDisabled(String provider) {
        Intent intent = new Intent("android.location.GPS_ENABLED_CHANGE");
        intent.putExtra("enabled", false);

    }
}

AND MY MANIFEST FILE

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.research.sos.smshelpcaller">
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.WRITE_SETTINGS"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.SEND_SMS"/>
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS"/>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    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>
</application>

I ALREADY TRY EVERYTHING BUT I DON'T KNOW WHAT IS WRONG IN MY CODES OR IS THERE SOMETHING MISSING.

LASTLY HERE IS THE LOGS IN LOGCAT

04-03 13:55:56.472 31224-31224/com.research.sos.smshelpcaller E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.research.sos.smshelpcaller, PID: 31224
java.lang.NullPointerException: Attempt to get length of null array
    at android.os.Parcel.readException(Parcel.java:1546)
    at android.os.Parcel.readException(Parcel.java:1493)
    at com.android.internal.telephony.ISms$Stub$Proxy.sendText(ISms.java:1430)
    at android.telephony.SmsManager.sendTextMessage(SmsManager.java:320)
    at com.research.sos.smshelpcaller.MainActivity$1.onClick(MainActivity.java:37)
    at android.view.View.performClick(View.java:5052)
    at android.view.View$PerformClick.run(View.java:20162)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5753)
    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:1405)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)

First of all, PLEASE DON'T SHOUT! Second of all, it's highly unlikely that you will get a log with no error. — Joe C, Apr 03 '18 at 05:27
First of all, please do not use all-capital letters. Second - please check adb log for more information. — Michał Zabielski, Apr 03 '18 at 05:28
why you change your question? first you post different logcat and now again change it. — Anuj Zunjarrao, Apr 03 '18 at 06:04
You edited your question, changed the original log output, and the question now points to totally different issue. You should look for the answer first - maybe someone already had the same problem. The error you have now does not correspond to original issue you had. — Michał Zabielski, Apr 03 '18 at 06:12
actually someone commented a code such as this setContentView(R.layout.activity_main); after i enter it the app don''t crash upon opening but if i try to push the button it crashes again giving this logs above — Jayson Ca-ong, Apr 03 '18 at 06:15
@JaysonCa-ong you should ask different question. dont changed original question becoz I gave you answer setContentView and some onw point to negative answer. — Anuj Zunjarrao, Apr 03 '18 at 06:18
sorry man... but your code actually helped ... but now this is the problem — Jayson Ca-ong, Apr 03 '18 at 06:23

score 1 · Accepted Answer · answered Apr 03 '18 at 05:43

1

where is your layout file, Give your xml reference to activity after super.onCreate(savedInstanceState);.

for example..

setContentView(R.layout.activity_main);

answered Apr 03 '18 at 05:43

Anuj Zunjarrao

426
2
14

it made some changes but when i try the button it crashes again – Jayson Ca-ong Apr 03 '18 at 06:01

score -1 · Answer 2 · answered Apr 03 '18 at 05:42

According to your log you try to invoke method on Null Pointer:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.research.sos.smshelpcaller.MainActivity.onCreate(MainActivity.java:23)

It means, that the code below does not resolve the R.id.emergency asset. It simply can't find it and the first line is set to null:

emergency= (Button) findViewById(R.id.emergency);
emergency.setOnClickListener(new View.OnClickListener() {...}

You should check if the name of the button you try to use is correct, if there is no spell mistakes, or even if the resource file (for example xml with view) exists.

i edited the log cat above ... and thats the latest error – Jayson Ca-ong Apr 03 '18 at 06:02 — Jayson Ca-ong, Apr 03 '18 at 06:02

User location sender app crashes when button is pushed

2 Answers2