Null pointer Exception - findViewById()

Question

Can anyone help me to find out what can be the issue with this program. In the onCreate() method the findViewById() returns null for all ids and th

Answer 1

What @Warlock said above is right , you should initial LinearLayout layout1, layout2, layout3 by the right way:

LinearLayout layout1 = (LinearLayout) View.inflate(this, R.layout.first_View, null);
LinearLayout layout2 = (LinearLayout) View.inflate(this, R.layout.second_View, null);
LinearLayout layout3 = (LinearLayout) View.inflate(this, R.layout.third, null);

wish my advise help you

Answer 2

In my case, it was a stupid mistake on my part. I had written code in the OnCreate method but it was above the setContentView line of code. Once I moved my code below this line the application started working fine.

setContentView(R.layout.activity_main);

Answer 3

Sometimes you need clean your project in Eclipse (Project - Clean..).

Answer 4

I have gotten this error today and it was so simple to clear, that I "facepalmed".

Just try to add the UI element to your layout xml File in your res/layout-port directory!!!

Answer 5

^{Emphasis added}

For those cases within an Activity class.

Activity.findViewById(int id)

Finds a view that was identified by the id attribute from the XML that was processed in onCreate(Bundle).

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Otherwise, such as an Fragment, Adapter, a View from a LayoutInflater, etc.

View.findViewById(int id)

Look for a child view with the given id. If this view has the given id, return this view.

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Either case,

Returns
The view if found or null otherwise.

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Now, re-check your XML files. Make sure you put the right value into setContentView or inflater.inflate.

In the case of an Activity, call findViewById after setContentView.

Then, make sure there is a View you are looking for with android:id="@+id/..." in that layout. Make sure the + is at @+id, which will add the resource to the R.id values to ensure you can find it from Java.

Answer 6

findViewById() returns a View if it exists in the layout you provided in setContentView(), otherwise it returns null and that's what happening to you.

Example if you setContentView(R.layout.activity_first); and then call findViewById(R.id.first_View); it will return a View which is your layout.

But if you call findViewById(R.id.second_View); it will return null since there is not a view in your activity_first.xml layout called @+id/second_View.