Simple WebView app keeps crashing

Question

I want an app that displays browser inside an app, but I get this error:

FATAL EXCEPTION: main Process: com.example.name.app, PID: 11672 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.name.app/com.example.name.app.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference

Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.name.app">
    <uses-permission android:name="android.permission.INTERNET"/>
    <application
        android:allowBackup="true"
        android:icon="@drawable/icon"
        android:label="@string/app_name"
        android:roundIcon="@drawable/icon"
        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>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout
    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"
    android:orientation="vertical">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="Click"/>

    <WebView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/webView"
        android:layout_width="fill_parent"
        android:layout_height="match_parent" />

</LinearLayout>

MainActivity.java

package com.example.name.app;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    Button button = (Button) findViewById(R.id.button);
    WebView browser = (WebView) findViewById(R.id.webView);
    String url = "http://www.google.com";

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

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                browser.setWebViewClient(new WebViewClient());
                browser.getSettings().setLoadsImagesAutomatically(true);
                browser.getSettings().setJavaScriptEnabled(true);
                browser.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
                browser.loadUrl(url);
            }
        });
    }
}

What is wrong? Thanks!

Initialization should be done after OnCreate() method! – Gowtham Subramaniam Dec 11 '17 at 09:09 — Gowtham Subramaniam, Dec 11 '17 at 09:09

score 1 · Accepted Answer · answered Dec 11 '17 at 08:57

You need to Bind Your Controls in onCreate() method like this

Do findViewById in your onCreate()

Try this

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

        Button button = (Button) findViewById(R.id.button);
        WebView browser = (WebView) findViewById(R.id.webView);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                browser.setWebViewClient(new WebViewClient());
                browser.getSettings().setLoadsImagesAutomatically(true);
                browser.getSettings().setJavaScriptEnabled(true);
                browser.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
                browser.loadUrl(url);
            }
        });
    }

ha.... works right away!!!! should've asked earlier. Thanks ! — belle park, Dec 11 '17 at 09:02

Simple WebView app keeps crashing

1 Answers1