Android problems using telephonyManager

Question

i have an android app in which i get connection status, connection type(WIFI, MOBILE) and the signal strength(for each type of connection).
The java code:

public class MainActivity extends Activity {
@Override
protected void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    final Button start = (Button) findViewById(R.id.button);
    final TextView status = (TextView) findViewById(R.id.status);
    final TextView type = (TextView) findViewById(R.id.type);
    final TextView speed = (TextView) findViewById(R.id.speed);
    final ConnectivityManager cm = (ConnectivityManager) getSystemService(this.CONNECTIVITY_SERVICE);
    final WifiManager wm = (WifiManager) getSystemService(this.WIFI_SERVICE);
    final TelephonyManager tm = (TelephonyManager) getSystemService(TELEPHONY_SERVICE);
    start.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            NetworkInfo netInfo = cm.getActiveNetworkInfo();
            WifiInfo wifiInfo = wm.getConnectionInfo();
            CellInfoGsm cellInfoGsm = (CellInfoGsm) tm.getAllCellInfo().get(0);
            CellSignalStrengthGsm cellSignal = cellInfoGsm.getCellSignalStrength();
            if (netInfo != null && netInfo.isConnected()) {
                status.setText("Status: connected");
                type.setText("Type: " + netInfo.getTypeName());
                if (type.getText().equals("Type: WIFI")) {
                    speed.setText("Signal: " + wifiInfo.getLinkSpeed()+ "dBm");
                }else{
                    speed.setText("Signal: " + cellSignal.getDbm() + "dBm");
                }
            }else{
                status.setText("Status: not connected");
                type.setText("Type: /");
                speed.setText("Signal: /");
            }
        }
    });
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, 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) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}}

And layout code:

<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:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"
android:id="@+id/layout">

<TextView android:text="Status: /" android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/status"
    android:textColor="#ff000000" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Start"
    android:id="@+id/button"
    android:layout_below="@+id/status"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="105dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Signal: /"
    android:id="@+id/speed"
    android:textColor="#ff000000"
    android:layout_below="@+id/type"
    android:layout_alignParentStart="true"
    android:layout_marginTop="21dp" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Type: /"
    android:id="@+id/type"
    android:layout_marginTop="20dp"
    android:layout_below="@+id/status"
    android:layout_alignParentStart="true"
    android:textColor="#ff000000" />

And the permission:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>

This works really well on the emulator(nexus 4 API 22/nexus 4 API 21) but when I test it on my Samsung Galaxy S4(Lollipop 5.0.1) it returns the error "Application has stopped". If I test it without telephonyManager(and the relative instructions) it works.
What could be the problem?
Thank you!
The logCat here: http://www.yourfilelink.com/get.php?fid=1165584

@Francesco, without logcat its really not worth of a shot in SO with this kind of force close problem — Amit K. Saha, Jan 18 '16 at 21:54
i'm new with android developing and i'm searching for logCat as soon as possible i post it — , Jan 18 '16 at 21:58
try this video https://www.youtube.com/watch?v=5ifsKD1twps to know about logcat :) — Amit K. Saha, Jan 18 '16 at 22:01
I guess it is . But you need to dump the log immediately after getting the force close. your log file does not have any fatal exception. — Amit K. Saha, Jan 18 '16 at 22:33

Amit K. Saha · Accepted Answer · 2016-01-18T22:43:07.830

0

There could be many reasons. Can't say exactly without the log. e.g.-

cm.getActiveNetworkInfo();

This may return null when testing in the real device cause there might not be a active network right now. Even if the device were connected, it could easily be a race condition.

Updated

You might be facing ClassCastException How could you be sure that tm.getAllCellInfo().get(0) is CellInfoGsm ? I don't know where do you live but it can be different like CellInfoLte Again can be told for sure without proper logs

edited Jan 18 '16 at 22:43

answered Jan 18 '16 at 21:59

Amit K. Saha

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Oh it coulds be right. So how can i get the signal strenght everywhere? – Jan 19 '16 at 06:56
check out http://stackoverflow.com/questions/17618167/get-signalstrength-without-using-phonestatelistener-onsignalstrengthchanged – Amit K. Saha Jan 19 '16 at 08:22

Android problems using telephonyManager

1 Answers1

Updated