maui android.instructions.md

Android Platform Development Guidelines

Guidance for Android handler implementations and platform code.

Common Build Issues

View Namespace Collision

Problem: Both MAUI and Android have a View type, causing ambiguous reference errors when implementing Android listeners or using Android View APIs.

Namespace collision between:

• Microsoft.Maui.Controls.View (MAUI's View type)
• Android.Views.View (Android's native View type)

Common symptoms:

error CS0234: The type or namespace name 'Views' does not exist in the namespace 'Android'
error CS0104: 'View' is an ambiguous reference between 'Microsoft.Maui.Controls.View' and 'Android.Views.View'

When this occurs:

• Implementing Android listeners: IOnLayoutChangeListener, IOnClickListener, IOnTouchListener
• Using Android View APIs directly
• Working with RecyclerView, ViewGroup, or Android layout classes
• Accessing Android view properties or methods

Solution: Use type aliases

Add type alias at the top of the file:

using AView = Android.Views.View;

Then use the alias throughout the file:

class LayoutChangeListener : Java.Lang.Object, AView.IOnLayoutChangeListener
{
    public void OnLayoutChange(AView v, int left, int top, int right, int bottom, 
                               int oldLeft, int oldTop, int oldRight, int oldBottom)
    {
        // Use AView to unambiguously refer to Android.Views.View
    }
}

Common type aliases used in MAUI Android code:

Alias	Full Type	When to Use
AView	Android.Views.View	View APIs, listeners
AColor	Android.Graphics.Color	vs Microsoft.Maui.Graphics.Color
ALayoutParams	Android.Views.ViewGroup.LayoutParams	Layout parameters
AContext	Android.Content.Context	vs Microsoft.Maui.ApplicationModel.Context (rare)

Alternative: Use global:: qualifier

If type alias would conflict with existing code:

class MyListener : Java.Lang.Object, global::Android.Views.View.IOnLayoutChangeListener
{
    public void OnLayoutChange(global::Android.Views.View v, ...)
    {
        // Explicit namespace qualification
    }
}