C#•12mo ago

❔ Xamarin.Forms Android App problem using Application.Context.StartActivity(intent)

Hi, in short, I created a super small Xamarin.Forms Android App. All I need is just to press a button, that will launch another application. Then I immedaitely added the button in the myPage.xaml file in the shared Xamarin.Forms project. About the myPage.xaml.cs file this is the code I binded to the button:

private void OnMyButtonClicked(object sender, EventArgs e)
{
  DependencyService.Get<IAppLauncher>().LaunchApp("com.android.chrome", "test");
}

private void OnMyButtonClicked(object sender, EventArgs e)
{
  DependencyService.Get<IAppLauncher>().LaunchApp("com.android.chrome", "test");
}

I defined the interface into App.xaml.cs (still shared project) using

public interface IAppLauncher
{
    void LaunchApp(string packageName, string data);
}

public interface IAppLauncher
{
    void LaunchApp(string packageName, string data);
}

Then I implmented it in the Android project by adding some code into MainActivity.cs

namespace AppExample1.Droid
{
    public class AppLauncherImplementation : IAppLauncher
    {
        public void LaunchApp(string packageName, string data)
        {
            var uri = Android.Net.Uri.Parse($"appexample2://data/{data}");
            var intent = new Intent(Intent.ActionView, uri);
            intent.SetPackage(packageName);

            var context = Android.App.Application.Context;
            context.StartActivity(intent);
        }
    }
}

namespace AppExample1.Droid
{
    public class AppLauncherImplementation : IAppLauncher
    {
        public void LaunchApp(string packageName, string data)
        {
            var uri = Android.Net.Uri.Parse($"appexample2://data/{data}");
            var intent = new Intent(Intent.ActionView, uri);
            intent.SetPackage(packageName);

            var context = Android.App.Application.Context;
            context.StartActivity(intent);
        }
    }
}

The problem is that every time I click the button, for some reason that I don't know, I always get error System.NullReferenceException: 'Object reference not set to an instance of an object.'

3 Replies

Accord•12mo ago

Looks like nothing has happened here. I will mark this as stale and this post will be archived until there is new activity.

Grin•12mo ago

I think this has something to do with

// Set the main layout for the activity
            SetContentView(Resource.Layout.activity_main);

// Set the main layout for the activity
            SetContentView(Resource.Layout.activity_main);

I could be wrong, but I've found that including layouts within my activity_main xml file this error dissappears.

<include
        android:id="@+id/id_SubStationMenu"
        layout="@layout/locationmenu"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone"/>

<include
        android:id="@+id/id_SubStationMenu"
        layout="@layout/locationmenu"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone"/>

Accord•12mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

Gaming

Programming

❔ Xamarin.Forms Android App problem using Application.Context.StartActivity(intent)