因为scrollbar是view的私有内部类，所以需要动态修改RecyclerView的scrollbar颜色， 只能通过反射获取scrollbar的drawable，然后用反射着色，亲测可用，代码直接粘贴就可使用。

import android.content.Context;
import android.content.res.ColorStateList;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.view.View;import androidx.annotation.NonNull;
import androidx.core.graphics.drawable.DrawableCompat;
import androidx.recyclerview.widget.RecyclerView;import java.lang.reflect.Field;
import java.lang.reflect.Method;public class ScrollBarUtil {public static void tintScrollbarColor(Context context, RecyclerView recyclerView) {try {//通过反射一层层的获取对象，直到获取到进度条Class<View> clazz = View.class;Method method = clazz.getDeclaredMethod("getScrollCache");method.setAccessible(true);Object scrollabilityCacheObj = method.invoke(recyclerView);Class<?> scrollabilityCacheClazz = scrollabilityCacheObj.getClass();Field scrollBarField = scrollabilityCacheClazz.getField("scrollBar");Object scrollbarObj = scrollBarField.get(scrollabilityCacheObj);Class<?> scrollbarClass = scrollbarObj.getClass();Field mVerticalThumbField = scrollbarClass.getDeclaredField("mVerticalThumb");Field mHorizontalThumbField = scrollbarClass.getDeclaredField("mHorizontalThumb");mVerticalThumbField.setAccessible(true);mHorizontalThumbField.setAccessible(true);Drawable mVerticalThumb = (Drawable) mVerticalThumbField.get(scrollbarObj);Drawable mHorizontalThumb = (Drawable) mHorizontalThumbField.get(scrollbarObj);//对显示的drawable着色Drawable mVerticalThumbTint = tintDrawable(mVerticalThumb, Color.parseColor("#6694FF"));Drawable mHorizontalThumbTint = tintDrawable(mHorizontalThumb, Color.parseColor("#6694FF"));//设置新的drawablemVerticalThumbField.set(scrollbarObj, mVerticalThumbTint);mHorizontalThumbField.set(scrollbarObj, mHorizontalThumbTint);} catch (Exception e) {e.printStackTrace();}}public static Drawable tintDrawable(@NonNull Drawable drawable, int color) {Drawable wrappedDrawable = DrawableCompat.wrap(drawable);DrawableCompat.setTint(wrappedDrawable, color);return wrappedDrawable;}public static Drawable tintDrawable(Drawable drawable, ColorStateList colors) {final Drawable wrappedDrawable = DrawableCompat.wrap(drawable);DrawableCompat.setTintList(wrappedDrawable, colors);return wrappedDrawable;}public static int getColorById(Context context, int color) {return context.getResources().getColor(color);}}