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androidandroid-fragmentscolorsandroid-actionbarxamarin

Change ActionBar color in a Fragment


In Xamarin, how can I change the ActionBar background color and text color in a Fragment?

Here is the code that works in an Activity:

ColorDrawable colorDrawable = new ColorDrawable(Color.White);
ActionBar.SetBackgroundDrawable(colorDrawable); 

int titleId = Resources.GetIdentifier("action_bar_title", "id", "android");
TextView abTitle = (TextView) FindViewById(titleId);
abTitle.SetTextColor (Color.Black);

If I have the same code, for the same project, in a Fragment, I get the following error:

An object reference is required for the non-static field, method, or property 'Android.App.ActionBar.SetBackgroundDrawable(Android.Graphics.Drawables.Drawable)'

At this line of code:

ActionBar.SetBackgroundDrawable(colorDrawable);

And if I comment out the above line of code, I get this error:

System.NullReferenceException: Object reference not set to an instance of an object

At this line of code:

abTitle.SetTextColor (Color.Black);

Also, I am placing this code in the OnCreateView function.

How does the code need to be changed so that it will work in a Fragment, rather than in an Activity?

Thanks in advance


Solution

  • I have found that to do this I need to manipulate the action bar from the activity

    Here is the code:

    public override void OnAttach(Activity activity)
    {
        base.OnAttach(activity);
        var colorDrawable = new ColorDrawable(Color.White);
        activity.ActionBar.SetBackgroundDrawable(colorDrawable);
    
        var titleId = activity.Resources.GetIdentifier("action_bar_title", "id", "android");
        var abTitle = activity.FindViewById<TextView>(titleId);
        abTitle.SetTextColor(Color.Black);
    }