android emulator app opens with blank white screen

Question

i had a running app but i wanted to implement push notifications so had to update android studio and put in the firebase dependencies which generated errors ,so had to move to androidx and changed dependency packages to androidx packages,these changes resolved the issues but when i am starting the app i get a blank white screen. below is the code from my MainActivity.java file.

package com.example.goldfish;

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.appcompat.app.AppCompatActivity;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.os.Parcelable;
import android.provider.MediaStore;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.webkit.ValueCallback;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.widget.ProgressBar;
//import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;

public class MainActivity extends AppCompatActivity{
    private static final int INPUT_FILE_REQUEST_CODE = 1;
    private static final int FILECHOOSER_RESULTCODE = 1;
    private static final String TAG = MainActivity.class.getSimpleName();
    private WebView webView;
    private ValueCallback<Uri> mUploadMessage;
    private Uri mCapturedImageURI = null;
    private ValueCallback<Uri[]> mFilePathCallback;
    private String mCameraPhotoPath;

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            if (requestCode != INPUT_FILE_REQUEST_CODE || mFilePathCallback == null) {
                super.onActivityResult(requestCode, resultCode, data);
                return;
            }
            Uri[] results = null;
            // Check that the response is a good one
            if (resultCode == Activity.RESULT_OK) {
                if (data == null) {
                    // If there is not data, then we may have taken a photo
                    if (mCameraPhotoPath != null) {
                        results = new Uri[]{Uri.parse(mCameraPhotoPath)};
                    }
                } else {
                    String dataString = data.getDataString();
                    if (dataString != null) {
                        results = new Uri[]{Uri.parse(dataString)};
                    }
                }
            }
            mFilePathCallback.onReceiveValue(results);
            mFilePathCallback = null;
        } else if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.KITKAT) {
            if (requestCode != FILECHOOSER_RESULTCODE || mUploadMessage == null) {
                super.onActivityResult(requestCode, resultCode, data);
                return;
            }
            if (requestCode == FILECHOOSER_RESULTCODE) {
                if (null == this.mUploadMessage) {
                    return;
                }
                Uri result = null;
                try {
                    if (resultCode != RESULT_OK) {
                        result = null;
                    } else {
                        // retrieve from the private variable if the intent is null
                        result = data == null ? mCapturedImageURI : data.getData();
                    }
                } catch (Exception e) {
                    Toast.makeText(getApplicationContext(), "activity :" + e,
                            Toast.LENGTH_LONG).show();
                }
                mUploadMessage.onReceiveValue(result);
                mUploadMessage = null;
            }
        }
        return;
    }
   // @Override
  /*  protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mSwipeRefreshLayout= (SwipeRefreshLayout) findViewById(R.id.swipe);
        mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                LoadWeb();
            }
        });
        LoadWeb();
    }
   protected void onCreate(Bundle savedInstanceState) {
        setContentView(R.layout.activity_main);
        mSwipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.container);
        mSwipeRefreshLayout.setOnRefreshListener(this);

        super.onCreate(savedInstanceState);
    }

    @Override
    public void onRefresh() {
        Toast.makeText(this, "Refresh", Toast.LENGTH_SHORT).show();
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                mSwipeRefreshLayout.setRefreshing(false);
            }
        }, 2000);
    }
*/
    public void LoadWeb(){
        webView = (WebView) findViewById(R.id.activity_main_webview);
        //private SwipeRefreshLayout mSwipeRefreshLayout;
        WebSettings webSettings = webView.getSettings();
        webView.loadUrl("https://google.com/"); //change with your website
       // swipe.setRefreshing(true);

        //code from youtube for performance
        webSettings.setJavaScriptEnabled(true);
        webSettings.setLoadWithOverviewMode(true);
        webSettings.setUseWideViewPort(true);
        webSettings.setSupportZoom(true);
        webView.getSettings().setBuiltInZoomControls(false);
        webView.getSettings().setDisplayZoomControls(false);
        webSettings.setLayoutAlgorithm(WebSettings.LayoutAlgorithm.NARROW_COLUMNS);
        webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
        webSettings.setDomStorageEnabled(true);
        webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
        webView.setScrollbarFadingEnabled(true);
        webView.getSettings().setRenderPriority(WebSettings.RenderPriority.HIGH);
        webView.getSettings().setAppCacheEnabled(true);

        webSettings.setSavePassword(true);
        webSettings.setSaveFormData(true);
        webSettings.setEnableSmoothTransition(true);
        if (Build.VERSION.SDK_INT >= 19) {
            webView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
        }
        else if(Build.VERSION.SDK_INT >=11 && Build.VERSION.SDK_INT < 19) {
            webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        }
        //end of performance improvement code
        webSettings.setLoadWithOverviewMode(true);
        webSettings.setAllowFileAccess(true);
        webView.setWebViewClient(new Client());
        webView.setWebChromeClient(new ChromeClient());
        int Permission_All = 1;
        String[] Permissions = {Manifest.permission.MEDIA_CONTENT_CONTROL, Manifest.permission.CAMERA};
        if (!hasPermissions(this, Permissions)) {
            ActivityCompat.requestPermissions(this, Permissions, Permission_All);
        }
    }

    private File createImageFile() throws IOException {
        // Create an image file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "JPEG_" + timeStamp + "_";
        File storageDir = Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES);
        File imageFile = File.createTempFile(
                imageFileName,  /* prefix */
                ".jpg",         /* suffix */
                storageDir      /* directory */
        );
        return imageFile;
    }


    public class ChromeClient extends WebChromeClient {
        // For Android 5.0
        public boolean onShowFileChooser(WebView view, ValueCallback<Uri[]> filePath, WebChromeClient.FileChooserParams fileChooserParams) {
            // Double check that we don't have any existing callbacks
            if (mFilePathCallback != null) {
                mFilePathCallback.onReceiveValue(null);
            }
            mFilePathCallback = filePath;
            Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
                // Create the File where the photo should go
                File photoFile = null;
                try {
                    photoFile = createImageFile();
                    takePictureIntent.putExtra("PhotoPath", mCameraPhotoPath);
                } catch (IOException ex) {
                    // Error occurred while creating the File
                    Log.e(TAG, "Unable to create Image File", ex);
                }
                // Continue only if the File was successfully created
                if (photoFile != null) {
                    mCameraPhotoPath = "file:" + photoFile.getAbsolutePath();
                    takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT,
                            Uri.fromFile(photoFile));
                } else {
                    takePictureIntent = null;
                }
            }
            Intent contentSelectionIntent = new Intent(Intent.ACTION_GET_CONTENT);
            contentSelectionIntent.addCategory(Intent.CATEGORY_OPENABLE);
            contentSelectionIntent.setType("image/*");
            Intent[] intentArray;
            if (takePictureIntent != null) {
                intentArray = new Intent[]{takePictureIntent};
            } else {
                intentArray = new Intent[0];
            }
            Intent chooserIntent = new Intent(Intent.ACTION_CHOOSER);
            chooserIntent.putExtra(Intent.EXTRA_INTENT, contentSelectionIntent);
            chooserIntent.putExtra(Intent.EXTRA_TITLE, "Image Chooser");
            chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, intentArray);
            startActivityForResult(chooserIntent, INPUT_FILE_REQUEST_CODE);
            return true;
        }




        // openFileChooser for Android 3.0+
        public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType) {
            mUploadMessage = uploadMsg;
            // Create AndroidExampleFolder at sdcard
            // Create AndroidExampleFolder at sdcard
            File imageStorageDir = new File(
                    Environment.getExternalStoragePublicDirectory(
                            Environment.DIRECTORY_PICTURES)
                    , "AndroidExampleFolder");
            if (!imageStorageDir.exists()) {
                // Create AndroidExampleFolder at sdcard
                imageStorageDir.mkdirs();
            }
            // Create camera captured image file path and name
            File file = new File(
                    imageStorageDir + File.separator + "IMG_"
                            + String.valueOf(System.currentTimeMillis())
                            + ".jpg");
            mCapturedImageURI = Uri.fromFile(file);
            // Camera capture image intent
            final Intent captureIntent = new Intent(
                    android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
            captureIntent.putExtra(MediaStore.EXTRA_OUTPUT, mCapturedImageURI);
            Intent i = new Intent(Intent.ACTION_GET_CONTENT);
            i.addCategory(Intent.CATEGORY_OPENABLE);
            i.setType("image/*");
            // Create file chooser intent
            Intent chooserIntent = Intent.createChooser(i, "Image Chooser");
            // Set camera intent to file chooser
            chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS
                    , new Parcelable[] { captureIntent });
            // On select image call onActivityResult method of activity
            startActivityForResult(chooserIntent, FILECHOOSER_RESULTCODE);
        }
        // openFileChooser for Android < 3.0
        public void openFileChooser(ValueCallback<Uri> uploadMsg) {
            openFileChooser(uploadMsg, "");
        }
        //openFileChooser for other Android versions
        public void openFileChooser(ValueCallback<Uri> uploadMsg,
                                    String acceptType,
                                    String capture) {
            openFileChooser(uploadMsg, acceptType);
        }
    }

    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // Check if the key event was the Back button and if there's history
        if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack()) {
            webView.goBack();
            return true;
        }
        // If it wasn't the Back key or there's no web page history, bubble up to the default
        // system behavior (probably exit the activity)
        return super.onKeyDown(keyCode, event);
    }

    public class Client extends WebViewClient {
        ProgressDialog progressDialog;

        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            // If url contains mailto link then open Mail Intent
            if (url.contains("mailto:")) {
                // Could be cleverer and use a regex
                //Open links in new browser
                view.getContext().startActivity(
                        new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
                // Here we can open new activity
                return true;
            }else {
                // Stay within this webview and load url
                view.loadUrl(url);
                return true;
            }
        }

        //Show loader on url load
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            // Then show progress  Dialog
            // in standard case YourActivity.this
//            if (progressDialog == null) {
//                progressDialog = new ProgressDialog(MainActivity.this);
//                progressDialog.setMessage("Loading...");
//                progressDialog.show();
//            }
//            view.setVisibility(webView.INVISIBLE);
        }

        // Called when all page resources loaded
        public void onPageFinished(WebView view, String url) {
            try {
                // Close progressDialog
//                if (progressDialog.isShowing()) {
//                    progressDialog.dismiss();
//                    progressDialog = null;
//                }
//                spinner.setVisibility(View.GONE);
//
//                view.setVisibility(webView.VISIBLE);
//                super.onPageFinished(view, url);
             //   swipe.setRefreshing(false);
                if (findViewById(R.id.splach_screen).getVisibility() == View.VISIBLE) {
// show webview
                    findViewById(R.id.swipe).setVisibility(View.VISIBLE);
// hide splash screen
                    findViewById(R.id.splach_screen).setVisibility(View.GONE);
                }
            } catch (Exception exception) {
                exception.printStackTrace();
            }
        }

    }

    //User Media Permission....as_060319
    public  static boolean hasPermissions (Context context, String... permissions){
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && context != null && permissions != null) {
            for(String permission: permissions) {
                if (ActivityCompat.checkSelfPermission(context, permission) != PackageManager.PERMISSION_GRANTED) {
                    return false;
                }
            }
        }
            return true;
    }
}

any help or insights will be very much appreciated.

Answer 1

According to the lifecycle of android Oncreate is first called and their we set our contentview with the layout using setcontentview(R.layout.activity_main) but it seems you have commented out your oncreate method.