[移动开发]android实现顶部悬浮效果

效果

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_home"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_behavior="com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior" />
    <LinearLayout
        android:id="@+id/home_header"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:background="@color/theme_color"
        android:paddingBottom="10dp"
        android:layout_alignParentStart="true">
        <include layout="@layout/home_header"/>
    </LinearLayout>
</RelativeLayout>

	private void initListener(){
        rvHome.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
                scrollY += dy;
                float alpha = Float.valueOf(scrollY) / 1000f * 255f;
                homeHeader.getBackground().setAlpha((int)alpha > 255 ? 255 : (int)alpha);
            }
        });
    }

任何艰辛都为了实现心中梦