How to fix NullPointerException is androd studio?

Question

I Build my own file sharing and website app using android studio.

The app is a very simple file sharing and website app, for which I already had to make a lot of fixes. Everything was working fine but in some phone it crashed.

Oh boy wasn't I wrong

The app builds fine, and working perfectly in my phone, but in some phones it will crashed.

below is my Videostatis.java which is connected to my website using wenview

--CODE--

package com.IApps.IndianShareIt.fragment;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DownloadManager;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.Bitmap;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Uri;
import android.os.Bundle;

import androidx.fragment.app.Fragment;
import okhttp3.Request;

import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.CookieManager;
import android.webkit.DownloadListener;
import android.webkit.URLUtil;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.LinearLayout;
import android.widget.Toast;

import com.IApps.IndianShareIt.ui.callback.IconSupport;
import com.IApps.IndianShareIt.ui.callback.TitleSupport;
import com.genonbeta.TrebleShot.R;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;

import static android.content.Context.DOWNLOAD_SERVICE;
import static androidx.core.content.ContextCompat.getSystemService;

/**
 * A simple {@link Fragment} subclass.
 */
public class VideoStatus extends Fragment implements IconSupport, TitleSupport {

    public WebView mWebView;
    private Dialog loadingDialog;

    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message message) {
            switch (message.what) {
                case 1:{
                    webViewGoBack();
                }break;
            }
        }
    };

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


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View v = inflater.inflate(R.layout.fragment_video_status, container, false);
        mWebView = (WebView)v.findViewById(R.id.webviewVideo);

        loadingDialog = new Dialog(getActivity());
        loadingDialog.setContentView(R.layout.loading);
        loadingDialog.getWindow().setBackgroundDrawable(getActivity().getDrawable(R.drawable.round_btn));
        loadingDialog.getWindow().setLayout(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT);
        loadingDialog.setCancelable(false);

        WebSettings settings = mWebView.getSettings();
        settings.setJavaScriptEnabled(true);
        settings.setSupportZoom(false);
        mWebView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
        mWebView.getSettings().setBuiltInZoomControls(false);
//        mWebView.loadUrl("https://indianshareitwhatsappstatus.blogspot.com/2020/07/blog-post.html");

        mWebView.setOnKeyListener(new View.OnKeyListener(){

            public boolean onKey(View v, int keyCode, KeyEvent event) {
                if (keyCode == KeyEvent.KEYCODE_BACK
                        && event.getAction() == MotionEvent.ACTION_UP
                        && mWebView.canGoBack()) {
                    handler.sendEmptyMessage(1);
                    return true;
                }

                return false;
            }

        });


        mWebView.setWebViewClient(new WebViewClient());

        mWebView.setDownloadListener(new DownloadListener() {
            public void onDownloadStart(String url, String userAgent,
                                        String contentDisposition, String mimetype,
                                        long contentLength) {
                Intent i = new Intent(Intent.ACTION_VIEW);
                i.setData(Uri.parse(url));
                startActivity(i);
            }
        });

        if(haveNetworkConnection()){
            mWebView.loadUrl("https://indianshareitwhatsappstatus.blogspot.com/2020/07/blog-post.html");
            mWebView.setWebViewClient(new WebViewClient(){
                @Override
                public void onPageStarted(WebView view, String url, Bitmap favicon) {
                    super.onPageStarted(view, url, favicon);
                    loadingDialog.show();
                }

                @Override
                public void onPageFinished(WebView view, String url) {
                    super.onPageFinished(view, url);
                    loadingDialog.dismiss();
                    mWebView.setVisibility(View.VISIBLE);
                }
            });
        } else {
            mWebView.loadUrl("file:///android_asset/error.html");
            final Handler ha=new Handler();
            ha.postDelayed(new Runnable() {

                @Override
                public void run() {
                    //call function
                    if (haveNetworkConnection()) {
                        mWebView.loadUrl("https://indianshareitwhatsappstatus.blogspot.com/2020/07/blog-post.html");
                        mWebView.setWebViewClient(new WebViewClient(){
                            @Override
                            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                                super.onPageStarted(view, url, favicon);
                                loadingDialog.show();
                            }

                            @Override
                            public void onPageFinished(WebView view, String url) {
                                super.onPageFinished(view, url);
                                loadingDialog.dismiss();
                                mWebView.setVisibility(View.VISIBLE);
                            }
                        });
                        return;
                    }
                    mWebView.loadUrl("file:///android_asset/error.html");
                    ha.postDelayed(this, 1000);
                }
            }, 1000);
        }


        mWebView.setDownloadListener(new DownloadListener()
        {

            @Override


            public void onDownloadStart(String url, String userAgent,
                                        String contentDisposition, String mimeType,
                                        long contentLength) {

                DownloadManager.Request request = new DownloadManager.Request(
                        Uri.parse(url));


                request.setMimeType(mimeType);


                String cookies = CookieManager.getInstance().getCookie(url);


                request.addRequestHeader("cookie", cookies);


                request.addRequestHeader("User-Agent", userAgent);


                request.setDescription("Downloading file...");


                request.setTitle(URLUtil.guessFileName(url, contentDisposition,
                        mimeType));


                request.allowScanningByMediaScanner();


                request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
                request.setDestinationInExternalPublicDir(
                        Environment.DIRECTORY_DOWNLOADS, URLUtil.guessFileName(
                                url, contentDisposition, mimeType));
                DownloadManager dm = (DownloadManager) getActivity().getSystemService(DOWNLOAD_SERVICE);
                dm.enqueue(request);
                Toast.makeText(getActivity().getApplicationContext(), "Downloading File Check Your Gallery When Download is Complete",
                        Toast.LENGTH_LONG).show();
            }});
        return v;
    }


    @Override
    public int getIconRes() {
        return R.drawable.ic_slow_motion_video_black_24dp;
    }

    @Override
    public CharSequence getTitle(Context context) {
        return context.getString(R.string.video_status);
    }

    private void webViewGoBack(){
        mWebView.goBack();
    }

    private boolean haveNetworkConnection() {
        boolean haveConnectedWifi = false;
        boolean haveConnectedMobile = false;

        ConnectivityManager cm = (ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo[] netInfo = cm.getAllNetworkInfo();

        for (NetworkInfo ni : netInfo) {
            if (ni.getTypeName().equalsIgnoreCase("WIFI"))
                if (ni.isConnected())
                    haveConnectedWifi = true;
            if (ni.getTypeName().equalsIgnoreCase("MOBILE"))
                if (ni.isConnected())
                    haveConnectedMobile = true;
        }
        return haveConnectedWifi || haveConnectedMobile;
    }

}

My app has been stopped in some phones and shows this error

You should be able to look at the line numbers and see which lines are at fault, we can't help because we don't see which lines are which numbers. — HopefullyHelpful, Jul 16 '20 at 13:42
Error is in 234 "NetworkInfo[] netInfo = cm.getAllNetworkInfo();" if source/exception are sync => "cm" is null, needs to be checked before "getAllNetworkInfo()" can be called. cause? don´t know, maybe app lacks permission for "(ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE)" — Michael Hauptmann, Jul 16 '20 at 13:46
You need to include the full stack trace so that we can see not only where the exception occurs, but how it got there. — NomadMaker, Jul 16 '20 at 14:30

score 0 · Answer 1 · answered Jul 16 '20 at 13:53

0

Watch your API-Level in your Manifest, in some cases, people have an older one than your minimum is

answered Jul 16 '20 at 13:53

Maximilian Fall

1
1

How to fix NullPointerException is androd studio?

1 Answers1