Why is my array of views returning null?

Question

I have a collection of switches in android; let's call them...

Switch one;
Switch two;
Switch three;
Switch four;
Switch five;

and I also have an array which contains these views.

Switch[] switchArray = {one, two, three, four, five};

and then, within my onCreateView() method; I assign all of those Switches using findViewById().

one = (Switch) findViewById(R.id.switchOne);
two = (Switch) findViewById(R.id.switchTwo);
three = (Switch) findViewById(R.id.switchThree);
four = (Switch) findViewById(R.id.switchFour);
five = (Switch) findViewById(R.id.switchFive);

Now; when I create a for-loop to check if that array is null:

    for(int i = 0; i<switchArray.length; i++){
      if(switchArray[i] == null){
         Log.d(TAG, "Array is null at:" + i);
     }
    }

I get the following logcat:

Array is null at: 1
Array is null at: 2
Array is null at: 3
Array is null at: 4
Array is null at: 5

and I am unsure as to why these variables are returning null if I tried to instantiate them in onCreate... if I also try to instantiate them before the onCreate (in the class header before any methods); I still get the same error.

Hopefully the problem is clear.

EDIT 1: FULL ONCREATEVIEW METHOD

public View onCreateView(LayoutInflater viewInflation, ViewGroup container,
            Bundle SavedInstantState) {
        superContext = getActivity().getApplicationContext();
        digitalfragmentview = viewInflation.inflate(
                R.layout.digitalfragment_page, container, false);

        digitalIO0Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio0mode);
        digitalIO1Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio1mode);
        digitalIO2Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio2mode);
        digitalIO3Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio3mode);
        digitalIO4Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio4mode);
        digitalIO5Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio5mode);
        digitalIO6Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio6mode);
        digitalIO7Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio7mode);
        digitalIO8Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio8mode);
        digitalIO9Mode = (Switch) digitalfragmentview
                .findViewById(R.id.digitalio9mode);

        // sets the listener for the mode switches
        for (int i = 0; i < digitalIOModeSwitchArray.length; i++) {
            if (digitalIOModeSwitchArray[i] == null) {
                Log.d(TAG, "Array is null at:" + i);
            }
        }

        return digitalfragmentview;
    }

When are you instantiating switchArray ? You need to instantiate it after you do your "findViewById" calls — dymmeh
– dymmeh, Commented Mar 3, 2014 at 15:55
the switchArray is instantiated before the onCreateView(); in the top of the class with all other class variables. — Tukajo
– Tukajo, Commented Mar 3, 2014 at 15:56
in my latest edition; digitalIO0Mode is equivalent to Switch One; etc etc... — Tukajo
– Tukajo, Commented Mar 3, 2014 at 15:59
You array will not be updated this way. You should instantiate your array after your findViewById calls. — dymmeh
– dymmeh, Commented Mar 3, 2014 at 16:01

njzk2 · Accepted Answer · 2014-03-03 16:02:51Z

3

Switch[] switchArray = {one, two, three, four, five};

contains references to one, two, three, four, five at the moment you create the array.

Latter, you reassign those variables, but your array still points to the previous references.

You need to create the array after you have assigned your views:

one = (Switch) findViewById(R.id.switchOne);
two = (Switch) findViewById(R.id.switchTwo);
three = (Switch) findViewById(R.id.switchThree);
four = (Switch) findViewById(R.id.switchFour);
five = (Switch) findViewById(R.id.switchFive);
// Then only
switchArray = {one, two, three, four, five};

answered Mar 3, 2014 at 16:02

njzk2

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3 Comments

Tukajo Over a year ago

Is there a way I can access that array with methods within my class then if it is now out of the scope of other methods within my class?

Tukajo Over a year ago

did you receive the comment notification?

njzk2 Over a year ago

you don't need to change it's scope. you can declare it as a member of your class, and still define it in the onCreate method.

Mobi · Accepted Answer · 2014-03-03 16:03:56Z

2

First take references to your widget in variables one = (Switch) findViewById(R.id.switchOne); two = (Switch) findViewById(R.id.switchTwo); three = (Switch) findViewById(R.id.switchThree); four = (Switch) findViewById(R.id.switchFour); five = (Switch) findViewById(R.id.switchFive);

then put them in an array

Switch[] switchArray = {one, two, three, four, five};

The reason is that Switch array is value type not reference type

answered Mar 3, 2014 at 16:03

Mobi

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Comments

Hariharan · Accepted Answer · 2014-03-03 16:03:19Z

1

Try this..

one = (Switch) findViewById(R.id.switchOne);

Instead of this..

one = findViewById(R.id.switchOne);

EDIT

switchArray[0] = (Switch) findViewById(R.id.switchOne);

edited Mar 3, 2014 at 16:03

answered Mar 3, 2014 at 15:53

Hariharan

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5 Comments

Tukajo Over a year ago

My apologies; I had that already I incorrectly formatted my code. Please refer to my latest update.

Hariharan Over a year ago

@Tukajo can you post your full onCreateView()

Tukajo Over a year ago

the additions have been made.

Hariharan Over a year ago

@Tukajo Is that all switches are in digitalfragment_page.xml

Tukajo Over a year ago

Yes; they are all in digitalfragment_page.xml.

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