Attempt to invoke virtual method android view

java.lang.NullPointerException: Attempt to invoke virtual method ‘android.view.View android.view.View.findViewById(int)’ on a null object reference

I have a BlankFragment

and it’s layout is:

Here is the MainActivity

and here is the layout of MainActivity

In the onCreate method of activity I am adding fragment to layout. This works fine unless I try to change the Text using setText method.

And I get this error:

referring to this line

Can somebody explain what’s causing this exception?

6 Answers 6

Don’t

Do

line causing issue, becuase calling setText method of Fragment before adding Fragment in FragmentManager .

Call setText method after adding bf Fragment:

The problem is FragmentTransaction is async by default

Then you still can’t get the Fragment yet, you have to get it from the FragmentTransaction

This article helped me to understand this problem better

do it in onCreateView();

You can use a temporary variable that can hold the String while the View is not yet created.

My assumption is that you want to instantiate your BlankFragment with some initial text as well as allowing the text to be set later on from your MainActivity .

In that case I would first change the the Fragment to accept an initial text like so:

The Activity code would then look like the following:

Note that the null-check of savedInstanceState is to guard for Activity-recreation for instance due to configuration changes.

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Attempt to invoke virtual method ‘ ‘on a null object reference

I am getting the following error

Attempt to invoke virtual method ‘void android.widget.StackView.setAdapter(android.widget.Adapter)’ on a null object reference

The complete fragment EventsFragment.java is

Stack_Adapter.java

Stack_Items

5 Answers 5

Your stackView is null . getActivity().findViewById returns null .

Why are you using getActivity() ?

Where is the stackView ? You should load it from the right xml.

as @Tauqir mentioned, you need to inflate the right xml like this:

Try this inside onCreateView

You first need to inflate the layout and call findViewById() on the View it returns, thus getActivity().findViewById should be rootView.findViewByID.

There are some other issues with your code as well. Like getctivity().getApplicationContext, just getActivity() is fine.

R.id.stackView1 is not found when you try to assign stackView , so it is null

change container and false to null

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What does «Attempt to Invoke Virtual Method» really mean?

I am a beginner level Android developer and every day is a fight with a lot of errors and their solutions. I have noticed that I quite many times get java.lang.NullPointerException: Attempt to invoke virtual method ‘xxx’ on a null object reference . Upto NullPointerException , it sounds familiar that something has value null but problem starts from next phrase. [follow the code please for problem]

In my opinion, I found this very unclear and as Android Studio unlike Eclipse only keeps saying Attempt to invoke virtual method ‘xxx’ on a null object reference for any sort of problem, it’s really hard to get know where I am missing point. Whether for cursors, database, arraylist and any object you can suppose, Android studio like crazy robot gives this error always.

Can anyone explain me what that really mean and what should be my approach in a general case I get this error?

Here is one of strange behaviour I am facing in my app and it is driving me crazy.

This function works fine

But another function gives me error

java.lang.NullPointerException: Attempt to invoke virtual method ‘android.database.Cursor android.database.sqlite.SQLiteDatabase.query(java.lang.String, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String, java.lang.String, java.lang.String)’ on a null object reference

Both functions have alike format and placed in same class, but why only second one gives error? If I think about NPE then it should also be the case with getAllRows() fucntion but it is not.

Edited

Function updateRow() is called in another class which describe some different database function, Here it is how —

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Attempt to invoke virtual method ‘void android.widget.TableLayout.addView(android.view.View)’ on a null object reference [duplicate]

I’m trying to use a table to show students data as the following :

When calling the students number value from the database to create rows as the same value, it gives me the following error: The code is :

the database type is SQLite and I’m using SQLiteOpenHelper. Any help would be greatly appreciated.

1 Answer 1

You probably don’t want the line setContentView(R.layout.activity_main); just the line setContentView(R.layout.activity_main5); (or vice-versa) depending upon which layout has the TableLayout and the TextViews etc that you use.

and then you want to include a line to instantiate the DataBaseConnection db. So add a line db = new DataBaseConnection(this); (immediately after the setContentView used).

If you still have issues with a null pointer exception then edit your question to include the stack-trace (i.e. not just the error message).

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Attempt to invoke virtual method ‘void android.widget.ImageView.setImageBitmap(android.graphics.Bitmap)’ on a null object reference

I keep getting this error and i’m not sure why. I’ve tried googling it but no luck there.

04-21 15:43:24.822 2461-2461/com.example.s.myapplication D/AndroidRuntime﹕ Shutting down VM 04-21 15:43:24.823 2461-2461/com.example.s.myapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main Process: com.example.s.myapplication, PID: 2461 java.lang.RuntimeException: Failure delivering result ResultInfo to activity : java.lang.NullPointerException: Attempt to invoke virtual method ‘void android.widget.ImageView.setImageBitmap(android.graphics.Bitmap)’ on a null object reference at android.app.ActivityThread.deliverResults(ActivityThread.java:3539) at android.app.ActivityThread.handleSendResult(ActivityThread.java:3582) at android.app.ActivityThread.access$1300(ActivityThread.java:144) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1327) 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.widget.ImageView.setImageBitmap(android.graphics.Bitmap)’ on a null object reference at com.example.s.myapplication.MainActivity.onActivityResult(MainActivity.java:46) at android.app.Activity.dispatchActivityResult(Activity.java:6139) at android.app.ActivityThread.deliverResults(ActivityThread.java:3535) at android.app.ActivityThread.handleSendResult(ActivityThread.java:3582) at android.app.ActivityThread.access$1300(ActivityThread.java:144) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1327) 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) a

This is my main activity. What the application is meant to do is:

1. Take a photo
2. Save the photo in a tmp location
3. load the photo into a imageview

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