webwiew de geri tusuna basında uygulama durduruldu hatası.

bu java kodu 

package com.example.yksdersnotlarimizz;

import androidx.appcompat.app.AppCompatActivity;

import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity {
    private WebView webView;
    private CustomWebViewClient webViewClient;
    private String Url = "http://yksnokta.blogspot.com";
    ProgressDialog mProgressDialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mProgressDialog = new ProgressDialog(this);
        mProgressDialog.setMessage("Yükleniyor...");

        webViewClient = new CustomWebViewClient();

        WebView webView = (WebView) findViewById(R.id.webview);
        webView.getSettings().setBuiltInZoomControls(true);
        webView.getSettings().setSupportZoom(true);
        webView.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
        webView.getSettings().setAllowFileAccess(true);
        webView.getSettings().setDomStorageEnabled(true);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.setWebViewClient(webViewClient);
        webView.loadUrl(Url);

    }

    private class CustomWebViewClient extends WebViewClient {
        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            super.onPageStarted(view, url, favicon);
            if (!mProgressDialog.isShowing()) {
                mProgressDialog.show();
            }
        }

        @Override
        public void onPageFinished(WebView view, String url) {
            super.onPageFinished(view, url);
            if (mProgressDialog.isShowing()) {
                mProgressDialog.dismiss();
            }
        }

        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            view.loadUrl(url);
            return true;
        }

        @Override
        public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {

        }
    }

    public void onBackPressed() {

        if (webView.canGoBack()){
              webView.goBack();
        } else {
            super.onBackPressed();
        }
    }
}

bu xml kodu 

<?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout 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:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <WebView android:id="@+id/webview" android:layout_width="match_parent" android:layout_height="match_parent" tools:layout_editor_absoluteX="8dp" tools:layout_editor_absoluteY="8dp" /> </androidx.constraintlayout.widget.ConstraintLayout>
 

 BU MANIFEST KODU 

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.yksdersnotlarimizz"> <uses-permission android:name="android.permission.INTERNET" /> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>