Material Slider: ACW type erasure clash when implementing OnChangeListener/OnSliderTouchListener

[sheiksyedm]

Description

After the fix in PR #1335 (which resolved missing AddOnChangeListener/AddOnSliderTouchListener methods), implementing Slider.IOnChangeListener or Slider.IOnSliderTouchListener in a .NET Android app causes a javac build error at ACW compilation time.

Error Message

javac error JAVAC0000:
BaseOnChangeListener cannot be inherited with different arguments:
<com.google.android.material.slider.Slider>

name clash: class SliderValueChangeListener has two methods
with the same erasure, yet neither overrides the other

first method:  onValueChange(Slider, float, boolean) in BaseOnChangeListener
second method: onValueChange(Object, float, boolean) in SliderValueChangeListener

Steps to Reproduce

1. Create a .NET Android project referencing Xamarin.Google.Android.Material (latest with PR Fixed Material Slider addOnChangeListener method missing issue #1335 fix)
2. Implement the slider change listener:

class SliderValueChangeListener : Java.Lang.Object, Google.Android.Material.Slider.Slider.IOnChangeListener
{
    public void OnValueChange(Google.Android.Material.Slider.Slider slider, float value, bool fromUser)
    {
        // Handle value change
    }
}

// Usage
slider.AddOnChangeListener(new SliderValueChangeListener());

3. Build the project → javac error during ACW compilation

Root Cause

The binding generates an erased OnValueChange(Object, float, bool) method on IBaseOnChangeListener (from the generic type parameter S). When the ACW creates a Java class implementing Slider.OnChangeListener (which extends BaseOnChangeListener<Slider>), Java sees two methods with the same erasure that don't override each other — causing the type clash.

The same issue affects BaseOnSliderTouchListener with OnStartTrackingTouch/OnStopTrackingTouch.

Expected Behavior

Implementing Slider.IOnChangeListener or Slider.IOnSliderTouchListener should compile and work without any javac errors.

Environment

• Xamarin.Google.Android.Material (any version with PR Fixed Material Slider addOnChangeListener method missing issue #1335 fix applied)
• .NET 9+ / .NET 10+
• Any target Android API level

Related

• PR Fixed Material Slider addOnChangeListener method missing issue #1335 introduced the addOnChangeListener fix that exposed this issue
• Affects both Slider and RangeSlider listener implementations