Geek Answers Handbook

SetContentView throws a Null Pointer exception

I have my main action trying to call a method from an imported package. I posted the call and method below. The error message I get is that the string

setContentView (twitterSite);

I get a zero point exception!

TweetToTwitterActivity twitter = new TweetToTwitterActivity(); twitter.loginNewUser(v, context);

Method

 public void loginNewUser(View v, Context context) { mPrefs = context.getSharedPreferences("twitterPrefs", MODE_PRIVATE); Log.i(TAG, "Got Preferences"); // Load the twitter4j helper mTwitter = new TwitterFactory().getInstance(); Log.i(TAG, "Got Twitter4j"); // Tell twitter4j that we want to use it with our app mTwitter.setOAuthConsumer(CONSUMER_KEY, CONSUMER_SECRET); try { Log.i(TAG, "Request App Authentication"); mReqToken = mTwitter.getOAuthRequestToken(CALLBACK_URL); Log.i(TAG, "Starting Webview to login to twitter"); WebView twitterSite = new WebView(context); twitterSite.requestFocus(View.FOCUS_DOWN); twitterSite.setOnTouchListener(new View.OnTouchListener() { public boolean onTouch(View v, MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: case MotionEvent.ACTION_UP: if (!v.hasFocus()) { v.requestFocus(); } break; } return false; } }); twitterSite.loadUrl(mReqToken.getAuthenticationURL()); setContentView(twitterSite); } catch (TwitterException e) { Log.e("HelloWorld", "Error in activity", e); Toast.makeText(this, "Twitter Login error, try again later", Toast.LENGTH_SHORT).show(); } }

Stacktrace

 09-26 08:21:12.123: ERROR/AndroidRuntime(171): Uncaught handler: thread main exiting due to uncaught exception 09-26 08:21:12.312: ERROR/AndroidRuntime(171): java.lang.NullPointerException 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.app.Activity.setContentView(Activity.java:1631) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at com.blundell.tut.ttt.TweetToTwitterActivity.loginNewUser(TweetToTwitterActivity.java:184) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at com.reason.max.Reason$3.onClick(Reason.java:239) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.View.performClick(View.java:2344) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.View.onTouchEvent(View.java:4133) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.widget.TextView.onTouchEvent(TextView.java:6510) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.View.dispatchTouchEvent(View.java:3672) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1712) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1202) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.app.Dialog.dispatchTouchEvent(Dialog.java:609) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1696) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.view.ViewRoot.handleMessage(ViewRoot.java:1658) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.os.Handler.dispatchMessage(Handler.java:99) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.os.Looper.loop(Looper.java:123) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at android.app.ActivityThread.main(ActivityThread.java:4203) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at java.lang.reflect.Method.invokeNative(Native Method) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at java.lang.reflect.Method.invoke(Method.java:521) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549) 09-26 08:21:12.312: ERROR/AndroidRuntime(171): at dalvik.system.NativeStart.main(Native Method)
+4
source share
2 answers

setContentView is a method of the Activity class. therefore, if your function is not in the activity class, you must specify the activity for which it should set the content.

 ((Activity) context).setContentView(twitterSite);

That's why you have to resort to casting to "Type" mode.

+7
source

first line in onCreate() should be

 super.onCreate(savedInstanceState);
0
source

More articles:


All Articles