Android application crashes after startup without any errors

Question

I have a problem with my android application. It worked fine before, but it started crashing immediately after start without any errors and I can't figure out why. I have commented (//) a lot of code in my classes and left there only things important for working, but still the same problem. I have a mainActivity and 2 fragments.

When I created fragments it automatically created folder layout and put java classes there. Fragment java classes (List, Set):

public class List extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_list, container, false);
    }
}

Main activity class:

public class MainActivity extends AppCompatActivity {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentPagerAdapter} derivative, which will keep every
     * loaded fragment in memory. If this becomes too memory intensive, it
     * may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    private SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    private ViewPager mViewPager;

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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);

        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);

        FloatingActionButton addButton = (FloatingActionButton) findViewById(R.id.add);
        addButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            switch(position) {
                case 0:
                    return new Set();
                case 1:
                    return new List();
                default:
                    return null;
            }
        }

        @Override
        public int getCount() {
            // Show 3 total pages.
            return 2;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return "ZADÁVÁNÍ";
                case 1:
                    return "SEZNAM";
            }
            return null;
        }
    }
}

activity_main.xml (auto-generated):

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="cz.sudoman281.kubirovacikalkulacka.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/appbar_padding_top"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways"
            app:popupTheme="@style/AppTheme.PopupOverlay">

        </android.support.v7.widget.Toolbar>

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

</android.support.design.widget.CoordinatorLayout>

fragments .xml files:

<FrameLayout 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"
    tools:context=".layout.List">

    <GridLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:text="List"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/textView6" />

        <ListView
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </GridLayout>
</FrameLayout>

Answer 1

From your log output, I saw this line:

01-01 15:01:58.206 7457-7457/cz.sudoman281.kubirovacikalkulacka W/System: ClassLoader referenced unknown path: /data/app/cz.sudoman281.kubirovacikalkulacka-1/lib/arm64

I guess there is something wrong with your native libraries, double check your Make or CMake buid files, make sure you're loading your native libraries correctly from the Java class.

Another thing if you're running your app on a device/emulator with Android Nougat, you may need to check that your native libraries are not linking against non-NDK libraries as described here: https://developer.android.com/about/versions/nougat/android-7.0-changes.html#ndk

Answer 2

The logcat filters does not always show logs when the app is getting started up. I faced a similar issue when integrating a library. This is how I found where the issue is.

Start the app in debug mode, set a breakpoint on the first line in onCreate method and keep steping over(F8) till you get the crash.