SecurityException when getting Wifi Scan Results

Question

I'm working with Android Studio on an app that, when I push a button, gives me the results of wifi scan! If I test the code alone (only the part "wifi scan") it works... But when I put it in the complete app, the app crashs! Why? I post my code:

//MAIN

    package com.example.pc1.tesiprova;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity
{


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

//CERCO GLI ELEMENTI BUTTON E BUTTON2

        Button OutDoor = (Button) findViewById(R.id.button);
        Button InDoor = (Button) findViewById(R.id.button2);

//CLICCANDO SU BUTTON FACCIO APRIRE UNA NUOVA ACTIVITY

        OutDoor.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                //DEFINISCO L'INTENZIONE DI APRIRE UNA NUOVA ACTIVITY
                Intent openActivityO=new Intent(MainActivity.this,ActivityO.class);
                //APRO L'ACTIVITY ACTIVITYO.JAVA
                startActivity(openActivityO);

            }
        });

//CLICCANDO SU BUTTON2 FACCIO APRIRE UNA NUOVA ACTIVITY

        InDoor.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {

                Intent openActivityI=new Intent(MainActivity.this,ActivityI.class);
                startActivity(openActivityI);

            }


        });
    }

//ACTIVITYO (that contains wifi scan!)

    package com.example.pc1.tesiprova;

import android.content.Context;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

import java.util.List;

public class ActivityO extends AppCompatActivity {

    public WifiManager wifi;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_o);

        TextView text1 = (TextView)findViewById(R.id.textView);
        TextView text2 = (TextView)findViewById(R.id.textView2);
        TextView text3 = (TextView)findViewById(R.id.textView3);

        wifi=(WifiManager)getSystemService(Context.WIFI_SERVICE);
        for(int i=0;i<5;i++);

        wifi.startScan();
        try{
            text1.setText("Sto cercando");
            Thread.sleep(3333);
        }
        catch(InterruptedException e)
        {
            e.printStackTrace();
        }

        List<ScanResult> results = wifi.getScanResults();


        String ssid1= results.get(0).SSID;
        String ssid2= results.get(1).SSID;
        String ssid3= results.get(2).SSID;

        Integer rssi1= results.get(0).level;
        Integer rssi2= results.get(1).level;
        Integer rssi3= results.get(2).level;

        text1.setText(ssid1+rssi1);
        text2.setText(ssid2+rssi2);
        text3.setText(ssid3+rssi3);

And the errors are:

    10-23 08:30:04.257    2230-2230/com.example.pc1.tesiprova I/art﹕ Not late-enabling -Xcheck:jni (already on)
10-23 08:30:04.257    2230-2230/com.example.pc1.tesiprova I/art﹕ Late-enabling JIT
10-23 08:30:04.259    2230-2230/com.example.pc1.tesiprova I/art﹕ JIT created with code_cache_capacity=2MB compile_threshold=1000
10-23 08:30:04.867    2230-2230/com.example.pc1.tesiprova W/System﹕ ClassLoader referenced unknown path: /data/app/com.example.pc1.tesiprova-1/lib/x86
10-23 08:30:05.276    2230-2252/com.example.pc1.tesiprova D/OpenGLRenderer﹕ Use EGL_SWAP_BEHAVIOR_PRESERVED: true
10-23 08:30:05.286    2230-2230/com.example.pc1.tesiprova D/﹕ HostConnection::get() New Host Connection established 0xac07fda0, tid 2230
10-23 08:30:05.459    2230-2252/com.example.pc1.tesiprova D/﹕ HostConnection::get() New Host Connection established 0xac07feb0, tid 2252
10-23 08:30:05.507    2230-2252/com.example.pc1.tesiprova I/OpenGLRenderer﹕ Initialized EGL, version 1.4
10-23 08:30:05.576    2230-2252/com.example.pc1.tesiprova W/EGL_emulation﹕ eglSurfaceAttrib not implemented
10-23 08:30:05.576    2230-2252/com.example.pc1.tesiprova W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xac130fc0, error=EGL_SUCCESS
10-23 08:31:14.500    2230-2252/com.example.pc1.tesiprova W/EGL_emulation﹕ eglSurfaceAttrib not implemented
10-23 08:31:14.500    2230-2252/com.example.pc1.tesiprova W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xac13f560, error=EGL_SUCCESS
10-23 08:31:14.812    2230-2252/com.example.pc1.tesiprova E/Surface﹕ getSlotFromBufferLocked: unknown buffer: 0xac0763b0
10-23 08:31:14.819    2230-2252/com.example.pc1.tesiprova D/OpenGLRenderer﹕ endAllStagingAnimators on 0xa42e1280 (RippleDrawable) with handle 0xac12fbd0
10-23 08:31:16.517    2230-2252/com.example.pc1.tesiprova W/EGL_emulation﹕ eglSurfaceAttrib not implemented
10-23 08:31:16.517    2230-2252/com.example.pc1.tesiprova W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xad9c7840, error=EGL_SUCCESS
10-23 08:31:17.043    2230-2230/com.example.pc1.tesiprova I/Choreographer﹕ Skipped 30 frames!  The application may be doing too much work on its main thread.
10-23 08:31:17.119    2230-2252/com.example.pc1.tesiprova E/Surface﹕ getSlotFromBufferLocked: unknown buffer: 0xac076c00
10-23 08:31:18.646    2230-2242/com.example.pc1.tesiprova I/art﹕ Background sticky concurrent mark sweep GC freed 9604(599KB) AllocSpace objects, 0(0B) LOS objects, 53% free, 1148KB/2MB, paused 1.649ms total 139.305ms
10-23 08:31:18.671    2230-2242/com.example.pc1.tesiprova W/art﹕ Suspending all threads took: 24.989ms
10-23 08:31:22.070    2230-2230/com.example.pc1.tesiprova D/AndroidRuntime﹕ Shutting down VM
    --------- beginning of crash
10-23 08:31:22.093    2230-2230/com.example.pc1.tesiprova E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.pc1.tesiprova, PID: 2230
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.pc1.tesiprova/com.example.pc1.tesiprova.ActivityO}: java.lang.SecurityException: Need ACCESS_COARSE_LOCATION or ACCESS_FINE_LOCATION permission to get scan results
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
            at android.app.ActivityThread.-wrap11(ActivityThread.java)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
     Caused by: java.lang.SecurityException: Need ACCESS_COARSE_LOCATION or ACCESS_FINE_LOCATION permission to get scan results
            at android.os.Parcel.readException(Parcel.java:1599)
            at android.os.Parcel.readException(Parcel.java:1552)
            at android.net.wifi.IWifiManager$Stub$Proxy.getScanResults(IWifiManager.java:1066)
            at android.net.wifi.WifiManager.getScanResults(WifiManager.java:1311)
            at com.example.pc1.tesiprova.ActivityO.onCreate(ActivityO.java:44)
            at android.app.Activity.performCreate(Activity.java:6237)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
            at android.app.ActivityThread.-wrap11(ActivityThread.java)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
10-23 08:31:24.168    2230-2230/? I/Process﹕ Sending signal. PID: 2230 SIG: 9

I have used these permissions:

<uses-permission android:name="android.permission.CHANGE_WIFI_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.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />

Thank you very much!!!!

Tetradymite

Can you put your manifest file here? – Cabbageworm

Crash report is contradictory. If you are providing the permission for ACCESS_COARSE_LOCATION in manifest, then this exception must not be there. I would suggest you to uninstall the app and run it again after cleaning the project. – Cuzco

Apart from your problem: you are blocking the UI thread with this Thread.sleep(3333);, I hope you are doing only for test purposes... – Leonaleonanie

This SecurityException crash happens to some of my customers but is not reproducible on my Android M device. My guess is that early versions of Android M threw the SecurityException but a later version changed it to return an empty list instead of throwing (probably in order to reduce the number of crashes on Android M). – Venal

Answer 1

It is possible that you are testing the application on Android 6.0 (for example in emulator). In that case you need to ask for the permission at runtime, it is not sufficient to declare it in manifest.

You need to check if the permission was granted (this is not a copy-paste code for you, you need to adjust it for your needs):

if (ContextCompat.checkSelfPermission(mContext, Manifest.permission.ACCESS_COARSE_LOCATION))
                     == PackageManager.PERMISSION_GRANTED) {
    //your code that requires permission
}

In order to ask for permission you need to use this code:

ActivityCompat.requestPermissions(activity, new String[] { Manifest.permission.ACCESS_COARSE_LOCATION },
                REQUEST_CODE);

For more details check developer guide: http://developer.android.com/training/permissions/requesting.html

Leonaleonanie

Answer 2

Please add ACCESS_FINE_LOCATION permission in manifest and try again.

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

Cabbageworm