i am using Fragments and a ViewPager with a TabLayout in my project , it is not running on devices

Question

I'm compared with many other apps. but I couldn't find out what I was wrong.

Here is what I did

[I changed gradle version 28.0.0-beta01 > 27.1.1, Check all xml files, clean & rebuild project, and I saw many videos about Viewpager with a TabLayout.]

activity_main(TabLayout + ViewPager), ganglist(ListView, id/list), list_item(1 ImageView, 2 Textview)

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    // Find the view pager that will allow the user to swipe between fragments
    ViewPager viewPager = findViewById(R.id.viewpager);
    // Create an adapter that knows which fragment should be shown on each page
    CategoryAdapter adapter = new CategoryAdapter(this,getSupportFragmentManager());
    // Set the adapter onto the view pager
    viewPager.setAdapter(adapter);

    TabLayout tabLayout= findViewById(R.id.tabs);
    // Connect the tab layout with the view pager. This will
    //   1. Update the tab layout when the view pager is swiped
    //   2. Update the view pager when a tab is selected
    //   3. Set the tab layout's tab names with the view pager's adapter's titles
    //      by calling onPageTitle()
    tabLayout.setupWithViewPager(viewPager);
   }
}

public class CategoryAdapter extends FragmentPagerAdapter {
private Context mContext;

public CategoryAdapter(Context context, FragmentManager fm) {
    super(fm);
    mContext = context;
}

@Override
public Fragment getItem(int position) {
    switch (position) {
        case 0:
            return new YeoidoFragment();
        case 1:
            return new YeoidoFragment();
        case 2:
            return new YeoidoFragment();
        default:
            return null;
    }
}


public int getCount() {
    return 1;
}


@Nullable
@Override
public CharSequence getPageTitle(int position) {
    switch (position) {
        case 0:
            return mContext.getString(R.string.yeouido_hangang_park);
        case 1:
            return mContext.getString(R.string.banpo_hangang_park);
        case 2:
            return mContext.getString(R.string.banpo_hangang_park);
        default:
            return null;
      }
   }
}

I'm using same Fragment for Test

public class Gang {
private int ImageResourceId;
private String Feature;
private String Explanation;

public Gang(int ImageResourceId, String Feature, String Explanation){
    this.ImageResourceId = ImageResourceId;
    this.Feature = Feature;
    this.Explanation = Explanation;
}

public int getImageResourceId(){return ImageResourceId;}
public void setImageResourceId(int ImageResourceId){
    this.ImageResourceId= ImageResourceId;
}
public String  getFeature(){return Feature;}
public void setFeature(String Feature){
    this.Feature = Feature;
}
public String getExplanation(){return Explanation;}
public void setExplanation(String Explanation){
    this.Explanation =  Explanation;
   }
}

public class GangAdapter extends ArrayAdapter<Gang> {
public GangAdapter(Context context, ArrayList<Gang>gangs){
    super(context, 0, gangs);
}

@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
    View listItemView = convertView;
    if(listItemView==null){
        listItemView= LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
    }
    Gang currentFeature = getItem(position);

    ImageView spotImageView = listItemView.findViewById(R.id.Image);
    spotImageView.setImageResource(currentFeature.getImageResourceId());

    TextView featureTextView = listItemView.findViewById(R.id.where);
    featureTextView.setText(currentFeature.getFeature());

    TextView detailTextView = listItemView.findViewById(R.id.about);
    detailTextView.setText(currentFeature.getExplanation());

    return listItemView;
   }
}

public class YeoidoFragment extends Fragment {


public YeoidoFragment() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

  View rootView= inflater.inflate(R.layout.ganglist, container, false);

  final ArrayList<Gang> gangs = new ArrayList<>();
  gangs.add(new Gang(R.drawable.yeouido1, getString(R.string.yeouido),getString(R.string.app_name)));

   GangAdapter adapter = new GangAdapter(getActivity(), gangs);

    ListView listView= rootView.findViewById(R.id.list);

    listView.setAdapter(adapter);
    return rootView;
   }
}

From logcat

08-06 21:32:41.805 8882-8882/com.example.android.hangangabout E/Zygote: isWhitelistProcess - Process is Whitelisted 08-06 21:32:41.806 8882-8882/com.example.android.hangangabout W/SELinux: SELinux selinux_android_compute_policy_index : Policy Index[2], Con:u:r:zygote:s0 RAM:SEPF_SM-G950N_8.0.0_0005, [-1 -1 -1 -1 0 1] 08-06 21:32:41.807 8882-8882/com.example.android.hangangabout I/SELinux: SELinux: seapp_context_lookup: seinfo=untrusted, level=s0:c512,c768, pkgname=com.example.android.hangangabout 08-06 21:32:41.810 8882-8882/com.example.android.hangangabout I/zygote64: Late-enabling -Xcheck:jni 08-06 21:32:41.878 8882-8882/com.example.android.hangangabout D/ActivityThread: Added TimaKeyStore provider 08-06 21:32:42.026 8882-8924/com.example.android.hangangabout I/vndksupport: sphal namespace is not configured for this process. Loading /vendor/lib64/egl/libGLES_mali.so from the current namespace instead. 08-06 21:32:42.036 8882-8882/com.example.android.hangangabout I/InstantRun: starting instant run server: is main process 08-06 21:32:42.045 8882-8924/com.example.android.hangangabout D/libEGL: loaded /vendor/lib64/egl/libGLES_mali.so 08-06 21:32:42.990 8882-9058/com.example.android.hangangabout D/OpenGLRenderer: HWUI GL Pipeline 08-06 21:32:43.001 8882-8882/com.example.android.hangangabout D/ViewRootImpl@c5bf86a[MainActivity]: setView = DecorView@4d5415b[MainActivity] TM=true MM=false 08-06 21:32:43.011 8882-8882/com.example.android.hangangabout D/ViewRootImpl@c5bf86a[MainActivity]: dispatchAttachedToWindow 08-06 21:32:43.067 8882-8882/com.example.android.hangangabout V/Surface: sf_framedrop debug : 0x4f4c, game : false, logging : 0 08-06 21:32:43.068 8882-8882/com.example.android.hangangabout D/ViewRootImpl@c5bf86a[MainActivity]: Relayout returned: old=[0,0][0,0] new=[0,0][1440,2960] result=0x7 surface={valid=true 539904405504} changed=true 08-06 21:32:43.091 8882-9058/com.example.and roid.hangangabout I/OpenGLRenderer: Initialized EGL, version 1.4 08-06 21:32:43.091 8882-9058/com.example.android.hangangabout D/OpenGLRenderer: Swap behavior 2 08-06 21:32:43.100 8882-9058/com.example.android.hangangabout D/libGLESv1: STS_GLApi : DTS, ODTC are not allowed for Package : com.example.android.hangangabout 08-06 21:32:43.101 8882-9058/com.example.android.hangangabout D/mali_winsys: EGLint new_window_surface(egl_winsys_display *, void *, EGLSurface, EGLConfig, egl_winsys_surface **, egl_color_buffer_format *, EGLBoolean) returns 0x3000, [1440x2960]-format:1 08-06 21:32:43.101 8882-9058/com.example.android.hangangabout D/OpenGLRenderer: eglCreateWindowSurface = 0x7dbb41daf0 08-06 21:32:43.458 8882-8882/com.example.android.hangangabout D/AbsListView: in onLayout changed 08-06 21:32:43.497 8882-8882/com.example.android.hangangabout D/AndroidRuntime: Shutting down VM 08-06 21:32:43.516 8882-8882/com.example.android.hangangabout E/AndroidRuntime: FATAL EXCEPTION: main Process: c om.example.android.hangangabout, PID: 8882 java.lang.RuntimeException: Canvas: trying to draw too large(132710400bytes) bitmap. at android.view.DisplayListCanvas.throwIfCannotDraw(DisplayListCanvas.java:229) at android.view.RecordingCanvas.drawBitmap(RecordingCanvas.java:97) at android.graphics.drawable.BitmapDrawable.draw(BitmapDrawable.java:529) at android.view.View.getDrawableRenderNode(View.java:20627) at android.view.View.drawBackground(View.java:20563) at android.view.View.draw(View.java:20343) at android.view.View.updateDisplayListIfDirty(View.java:19297) at android.view.View.draw(View.java:20075) at android.view.ViewGroup.drawChild(ViewGroup.java:4421) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207) at android.view.View.updateDisplayListIfDirty(View.java:19288) at android.view.View.draw(View.java:20075) at android.view.ViewGroup.drawChild(ViewGroup.java:4421) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207) at android.view.View.updateDisplayListIfDirty(View.java:19288) at android.view.View.draw(View.java:20075) at android.view.ViewGroup.drawChild(ViewGroup.java:4421) at android.vi ew.ViewGroup.dispatchDraw(ViewGroup.java:4207) at android.view.View.updateDisplayListIfDirty(View.java:19288) at android.view.View.draw(View.java:20075) at android.view.ViewGroup.drawChild(ViewGroup.java:4421) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207) at android.view.View.updateDisplayListIfDirty(View.java:19288) at android.view.View.draw(View.java:20075) at android.view.ViewGroup.drawChild(ViewGroup.java:4421) at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207) at android.view.View.draw(View.java:20355) at com.android.internal.policy.DecorView.draw(DecorView.java:979) at android.view.View.updateDisplayListIfDirty(View.java:19297) at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:686) at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:692) at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:800) at android.view.ViewRootImpl.draw(ViewRootImpl.java:3451) at android.view.ViewRootImpl.performDraw(Vie wRootImpl.java:3238) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2773) at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1742) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7763) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911) at android.view.Choreographer.doCallbacks(Choreographer.java:723) at android.view.Choreographer.doFrame(Choreographer.java:658) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897) at android.os.Handler.handleCallback(Handler.java:789) at android.os.Handler.dispatchMessage(Handler.java:98) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6938) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:327) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1374)

Answer 1

I think int getCount() should return 3

you should define or create a Array list adapter on

public void onViewCreated(View view, @Nullable Bundle saveInstanceState) {

}

Answer 2

As the logcat is reporting, you are trying to draw a way to big bitmap into your canvas:

 FATAL EXCEPTION: main Process: com.example.android.hangangabout, PID: 8882 java.lang.RuntimeException: Canvas: trying to draw too large(132710400bytes) bitmap.

This are more than 132 megabytes! You should scale the image before drawing. In general there is no need for such big bitmaps, since your device has not enough pixels to display it anyway.

In addition having such big objects is dangerous since the RAM limit for you app is limited by the device (the limit depends on the device). Often it's only 32mb of ram that can be used by your app.