Null exception in browser activity during url open

Question

I have an activity with only browser view. Every time application tries to open url I get this exception:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.webkit.WebView.loadUrl(java.lang.String)' on a null object reference

that refers to this line:

mWebView.loadUrl("http://google.com");

After commenting this line, activity opens normal from the other view. Here is the code that tries to load web page:

 public class Browser extends AppCompatActivity {


 WebView mWebView;
/**
 * ATTENTION: This was auto-generated to implement the App Indexing API.
 * See https://g.co/AppIndexing/AndroidStudio for more information.
 */
private GoogleApiClient client;

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

    mWebView = (WebView) findViewById(R.id.webView);


       mWebView.loadUrl("http://google.com");


    // ATTENTION: This was auto-generated to implement the App Indexing API.
    // See https://g.co/AppIndexing/AndroidStudio for more information.
    client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}

Logcat:

java.lang.RuntimeException: Unable to start activity ComponentInfo{karolklimek.mpkdisplay2/karolklimek.mpkdisplay2.Browser}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.webkit.WebView.loadUrl(java.lang.String)' on a null object reference
                                                                             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
                                                                             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
                                                                             at android.app.ActivityThread.access$800(ActivityThread.java:144)
                                                                             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
                                                                             at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                             at android.os.Looper.loop(Looper.java:135)
                                                                             at android.app.ActivityThread.main(ActivityThread.java:5221)
                                                                             at java.lang.reflect.Method.invoke(Native Method)
                                                                             at java.lang.reflect.Method.invoke(Method.java:372)
                                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
                                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
                                                                          Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.webkit.WebView.loadUrl(java.lang.String)' on a null object reference
                                                                             at karolklimek.mpkdisplay2.Browser.onCreate(Browser.java:38)
                                                                             at android.app.Activity.performCreate(Activity.java:5933)
                                                                             at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
                                                                             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
                                                                             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
                                                                             at android.app.ActivityThread.access$800(ActivityThread.java:144) 
                                                                             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
                                                                             at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                             at android.os.Looper.loop(Looper.java:135) 
                                                                             at android.app.ActivityThread.main(ActivityThread.java:5221) 
                                                                             at java.lang.reflect.Method.invoke(Native Method) 
                                                                             at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
                                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 

And the content of content_browser XML file:

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="karolklimek.mpkdisplay2.Browser"
    >
<WebView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/webView"
    android:layout_alignParentBottom="true"
    android:layout_alignParentEnd="true"
    android:layout_alignParentTop="true"
    android:layout_alignParentStart="true" />

</RelativeLayout>

Answer 1

You have a mistake in setContentView(). You have to pass the integer value of your layout from R.java file. Thus you have to pass R.layout.activity_browser instead of layout.activity_browser.

It should be

setContentView(R.layout.activity_browser);

UPDATE

In your code, you are setting the content view to be activity_browser but from your question, I understand that you have the webview in content_browser.xml file, and thus you are getting an NPE.

Simplest way to solve the error would be to move the webview to your activity_browser.xml or change your setContentView to load content_browser instead of activity_browser.