Find a TextView from a View that has been Inflated

Question

In Xamarin, if I Inflate a View, how can I set the text of a TextView in the View?

I am wanting to code an application where I can call methods in different fragments to pass values between fragments and display these values.

Here is my MainActivity code:

public class MainActivity : FragmentActivity
{
    string message;

    FragmentOrange fragOrange;
    FragmentGreen fragGreen;
    FragmentRed fragRed;

    protected override void OnCreate (Bundle bundle)
    {
        base.OnCreate (bundle);

        SetContentView (Resource.Layout.activity_main);

        fragOrange = new FragmentOrange ();
        fragGreen = new FragmentGreen ();
        fragRed = new FragmentRed ();

        List<Android.Support.V4.App.Fragment> fragments = new List<Android.Support.V4.App.Fragment>();
        fragments.Add(fragOrange);
        fragments.Add(fragGreen);
        fragments.Add(fragRed);

        MyPagerAdapter pageAdapter = new MyPagerAdapter(SupportFragmentManager, fragments);
        var pager = FindViewById<ViewPager>(Resource.Id.myViewPager);
        pager.Adapter = pageAdapter;

        pager.SetCurrentItem (0, true);
        fragOrange.SetMessage ("Fragment orange");
    }
}

Here is my FragmentOrange code:

public class FragmentOrange : Android.Support.V4.App.Fragment
{
    string message;
    TextView textViewDisplay;
    View view;

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        view = inflater.Inflate(Resource.Layout.fragment_orange, container, false);
        textViewDisplay = view.FindViewById<TextView>(Resource.Id.textViewDisplay);
        return view;
    }

    public void SetMessage(string value)
    {
        message = value;
        textViewDisplay.Text = value;
    }
}

When I call the SetMessage function, I get the following error:

Object reference not set to an instance of an object

At this line of code:

textViewDisplay.Text = value;

Here is my Layout code:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <TextView
        android:text="Text"
        android:id="@+id/textViewDisplay"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

Thanks in advance

Please edit your question with log cat – Engr Waseem Arain Mar 26 '14 at 07:28 — Engr Waseem Arain, Mar 26 '14 at 07:28

score 0 · Answer 1 · answered Mar 26 '14 at 07:29

var textView = view.FindViewById<TextView>(Resource.Id.textViewDisplay);

should be

TextView textview = (TextView) findViewById(R.id.textViewDisplay);

please note, that you cannot update a textview from an activity without a handler, as it is a part of the UI.

//before oncreate
private int i;
Handler handler;

//oncreate
i = 0;
        handler = new Handler();
        handler.post(mUpdate);

//before the last closing bracket in your activity
     Runnable mUpdate = new Runnable(){
            public void run() {
                textview.setText("your string here");

                i++;

                handler.postDelayed(this, 1000);
            }
          };

Can you please show me where I should have this code in my application? — Garry, Mar 26 '14 at 08:02

score 0 · Answer 2 · edited Mar 26 '14 at 07:52

0

TextView textView = view.FindViewById<TextView>(Resource.Id.textViewDisplay);

Add this line below after inflating the view. I mean in OncreateView.

edited Mar 26 '14 at 07:52

tharkay

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answered Mar 26 '14 at 07:30

anjaneya

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I have done this, however I am still getting the error. – Garry Mar 26 '14 at 07:59

score 0 · Answer 3 · answered Mar 26 '14 at 07:34

0

Change this line

    var textView = view.FindViewById<TextView>(Resource.Id.textViewDisplay);

to this:

    TextView textView = (TextView)view.findViewById(R.id.textViewDisplay);

Bw you should define and inflate your view like this:

    LinearLayout view;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

        view = (LinearLayout) inflater.inflate(
        R.layout.fragment_orange, container, false);

        return view;
    }

answered Mar 26 '14 at 07:34

Sayed Jalil Hassan

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Do I need to use the LinearLayout type for the View, or can I just use the generic View? – Garry Mar 26 '14 at 08:01
I am not sure about that. you need to try it. but i think you need to define a particular type for your parent view. – Sayed Jalil Hassan Mar 26 '14 at 08:03

score 0 · Answer 4 · answered Mar 26 '14 at 07:36

0

Try that:

var textView = view.FindViewById<TextView>(Resource.Id.textViewDisplay);

Change to:

TextView textview = (TextView) view.findViewById(R.id.textViewDisplay);

then

view.text.setText(message);

answered Mar 26 '14 at 07:36

Engr Waseem Arain

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Find a TextView from a View that has been Inflated

4 Answers4