Android app working on 2.3 but not on 4.0

Question

Ok, I have been working on a Android application for a while. It's basicaly a RSS reciever. I use RSS to check the news, weather forecast, TV schedule and Horoscope.

Everything was fine while I was testing it on Android 2.3.3, 2.3.6 and even on 2.1; but when I sent it to my friend who has Android 4.0 it did not work. I was suspicious so I tested it on emulator. Nor 4.0, nor 4.1 Emulators can run it. Here I provide Manifest and one class. If anybody knows how to fix this, that will be great.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="XXX.XXXXX.XXX"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="7"
    android:targetSdkVersion="14" />

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".Vodic"
        android:label="@string/title_activity_pocetna" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity
        android:name=".Pomoc"
        android:label="@string/m_tel_vodi_za_odlu_ne"
        ></activity>
    <activity
        android:name=".Pomocna"
        android:label="@string/m_tel_vodi_za_odlu_ne"
        ></activity>
    .
    .
    .

    <activity
        android:name=".TvRasporedTreca"
        android:label="@string/m_tel_vodi_za_odlu_ne"
        ></activity>

</application>

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

<!-- Needed to check when the network connection changes -->
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>

</manifest>

And here's one class:

public class Vodic extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_pocetna);
    Button tv = (Button)findViewById(R.id.tv);
    Button vijesti = (Button)findViewById(R.id.vijesti);
    Button horoskop = (Button)findViewById(R.id.horoskop);
    Button vremenska_prognoza = (Button)findViewById(R.id.vremenska_prognoza);
    Button o_aplikaciji = (Button)findViewById(R.id.o_aplikaciji);
    Button pomoc = (Button)findViewById(R.id.pomoc);

    tv.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {
            Intent fy=new Intent(getApplicationContext(), TV_Raspored.class);
            startActivity(fy);
        }
    });

    .
    .
    .

    pomoc.setOnClickListener(new View.OnClickListener() {
        @Override
    public void onClick(View arg0) {
            Intent fy=new Intent(getApplicationContext(), Pomoc.class);
            startActivity(fy);
        }
    });

}

public boolean isOnline() {
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    if(netInfo != null && netInfo.isConnected()) {
        return true;
    }
    return false;
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_pocetna, menu);
    return true;
}
}

So, to sum up. It works on 2.1 and 2.3.3 but doesn't on 4.0 and 4.1 . I have no Idea what's wrong.. so if anybody knows, please help..

Answer 1

From Android 3.x and onward Google has added some checks that generate errors if your application employs very bad practices.
Without a log it is hard to confirm, but the most likely scenario is that you are making network operations in the core of your activities, generating a NetworkOnUIThread exception.
It is NOT a bug in the Android framework. The problem is that your activities run in the main thread, ie the UI thread.
So when you make a network call in an Activity, the whole UI freezes until you get an answer (or a timeout); which is something that you absolutely want to avoid. An easy solution to this issue is to use AsyncTask : it is an easy to implement built-in solutions to make operations in a secondary thread.