Webview crashing android app on startup

Question

I'm using webview in an android app and I'm trying to get it to start automatically on the second time the app is started after saving the settings. After setting breakpoints I was able to determine the app is crashing on line "mWebView.setWebChromeClient(new WebChromeClient()" in WebActivity. I get the error source not found in debugger.

WebActivity:

public class WebActivity extends Activity 
{

WebView mWebView;

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    final Activity mActivity = this;

    // Adds Progress bar Support
    this.getWindow().requestFeature(Window.FEATURE_PROGRESS);
    setContentView(R.layout.activity_web);


    // Makes Progress bar Visible
    getWindow().setFeatureInt( Window.FEATURE_PROGRESS, Window.PROGRESS_VISIBILITY_ON);

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

    mWebView.getSettings().setBuiltInZoomControls(true);
    mWebView.getSettings().setJavaScriptEnabled(true);
    mWebView.getSettings().setDomStorageEnabled(true);

    mWebView.setWebViewClient(new WebViewClient());
    mWebView.setWebChromeClient(new WebChromeClient() 
    {
        public void onProgressChanged(WebView view, int progress)  
        {
            //Make the bar disappear after URL is loaded, and changes string to Loading...
            findViewById(R.id.webview).setVisibility(View.GONE);
            mActivity.setTitle("Loading...");
            mActivity.setProgress(progress * 100); //Make the bar disappear after URL is loaded

            // Return the app name after finish loading
            if(progress == 100)
            {
                mActivity.setTitle(R.string.webtitle);
                findViewById(R.id.webview).setVisibility(View.VISIBLE);
            }
        }
    });
    Bundle b = getIntent().getExtras();
    mWebView.loadUrl("http://" + (b.getString("iptextfield")) + "/index.html");
    WebView wv = (WebView) findViewById(R.id.webview);
    wv.setWebViewClient(new WebViewClient() 
    {
    boolean toast_f = true;
       @Override
       public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) 
       {
           Context context = getApplicationContext();
           CharSequence text = "Loading...(this may take up to 60 seconds)";

           if (toast_f)
           {
               toast_f = false;
               int duration = Toast.LENGTH_LONG;
               Toast toast = Toast.makeText(context, text, duration);
               toast.setGravity(Gravity.CENTER|Gravity.CENTER,0,0);
               toast.show();
           }

           Bundle b = getIntent().getExtras();
           mWebView.loadUrl("http://" + (b.getString("iptextfield")) + "/index.html");
       }
    });
}

}

Main activity:

public class MainActivity extends Activity 
{

@Override
protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    Intent intent;

    SharedPreferences sharedPref= getSharedPreferences("mypref", 0);
    String GetStatus = sharedPref.getString("DataSaved", "");

    if (GetStatus.equals("true")) 
    {
       intent = new Intent(this, WebActivity.class);
    } 
    else 
    {
       intent = new Intent(this, SetupActivity.class);
    }

    startActivity(intent);
    finish();
}

}

Here's the logcat errors I get when just running the app:

08-19 12:25:54.407: W/dalvikvm(15158): threadid=1: thread exiting with uncaught      exception (group=0x4202d438)
08-19 12:25:54.407: E/AndroidRuntime(15158): FATAL EXCEPTION: main
08-19 12:25:54.407: E/AndroidRuntime(15158): java.lang.RuntimeException: Unable to  start activity ComponentInfo{com.webpage.WebActivity}: java.lang.NullPointerException
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2073)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2098)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.app.ActivityThread.access$600(ActivityThread.java:138)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1204)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.os.Looper.loop(Looper.java:137)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.app.ActivityThread.main(ActivityThread.java:4911)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at java.lang.reflect.Method.invokeNative(Native Method)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at java.lang.reflect.Method.invoke(Method.java:511)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at dalvik.system.NativeStart.main(Native Method)
08-19 12:25:54.407: E/AndroidRuntime(15158): Caused by: java.lang.NullPointerException
08-19 12:25:54.407: E/AndroidRuntime(15158):    at com.webpage.WebActivity.onCreate(WebActivity.java:58)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.app.Activity.performCreate(Activity.java:5240)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1082)
08-19 12:25:54.407: E/AndroidRuntime(15158):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2037)
08-19 12:25:54.407: E/AndroidRuntime(15158):    ... 11 more

A--C · Accepted Answer

For the sake of a more complete answer:

The line that the NullPointerException occurred on is 58, which happens to be

mWebView.loadUrl("http://"(b.getString("iptextfield")) + "/index.html");

At first glance, mWebView, b.getString() or b could be null.

mWebView was already used before without issue so it shouldn't be null.

The String returned by b.getString() is concatenated with two other strings, so that won't throw an NPE.

So that leaves b itself.

This should make sense as in MainActivity, you are starting WebActivity but not adding any extras to its Intent.

Use Intent#putExtra() to add extras to the intent, before starting the next Activity.

Then, as @siik suggested, it is good practise to make sure your Bundle is not null:

if (b != null){
   mWebView.loadUrl("http://" + (b.getString("iptextfield")) + "/index.html");
}

You could even go a little further and check to see if b actually contains the key you are looking for.

if (b != null && b.containsKey ("iptextfield")){
      mWebView.loadUrl("http://" + (b.getString("iptextfield")) + "/index.html");
}

Webview crashing android app on startup

Answers (2)

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