Use DatePicker spinners in API 24

gistfile1.java

/**
 * Workaround for this bug: https://code.google.com/p/android/issues/detail?id=222208
 * In Android 7.0 Nougat, spinner mode for the DatePicker in DatePickerDialog is
 * incorrectly displayed as calendar, even when the theme specifies otherwise.
 *
 * Modified slightly from the equivalent fix for TimePicker from @jeffdgr8: 
 *     https://gist.github.com/jeffdgr8/6bc5f990bf0c13a7334ce385d482af9f
 */
private void fixSpinner(Context context, int year, int month, int dayOfMonth) {
    // The spinner vs not distinction probably started in lollipop but applying this
    // for versions < nougat leads to a crash trying to get DatePickerSpinnerDelegate
    if (Build.VERSION.SDK_INT == Build.VERSION_CODES.N) {
        try {
            // Get the theme's android:datePickerMode
            final int MODE_SPINNER = 1;
            Class<?> styleableClass = Class.forName("com.android.internal.R$styleable");
            Field datePickerStyleableField = styleableClass.getField("DatePicker");
            int[] datePickerStyleable = (int[]) datePickerStyleableField.get(null);
            final TypedArray a = context.obtainStyledAttributes(null, datePickerStyleable,
                    android.R.attr.datePickerStyle, 0);
            Field datePickerModeStyleableField = styleableClass.getField("DatePicker_datePickerMode");
            int datePickerModeStyleable = datePickerModeStyleableField.getInt(null);
            final int mode = a.getInt(datePickerModeStyleable, MODE_SPINNER);
            a.recycle();

            if (mode == MODE_SPINNER) {
                DatePicker datePicker = (DatePicker) findField(DatePickerDialog.class,
                        DatePicker.class, "mDatePicker").get(this);
                Class<?> delegateClass = Class.forName("android.widget.DatePicker$DatePickerDelegate");
                Field delegateField = findField(DatePicker.class, delegateClass, "mDelegate");
                Object delegate = delegateField.get(datePicker);

                Class<?> spinnerDelegateClass = Class.forName("android.widget.DatePickerSpinnerDelegate");

                // In 7.0 Nougat for some reason the datePickerMode is ignored and the
                // delegate is DatePickerCalendarDelegate
                if (delegate.getClass() != spinnerDelegateClass) {
                    delegateField.set(datePicker, null); // throw out the DatePickerCalendarDelegate!
                    datePicker.removeAllViews(); // remove the DatePickerCalendarDelegate views

                    Constructor spinnerDelegateConstructor = spinnerDelegateClass
                            .getDeclaredConstructor(DatePicker.class, Context.class,
                                    AttributeSet.class, int.class, int.class);
                    spinnerDelegateConstructor.setAccessible(true);

                    // Instantiate a DatePickerSpinnerDelegate
                    delegate = spinnerDelegateConstructor.newInstance(datePicker, context,
                            null, android.R.attr.datePickerStyle, 0);

                    // set the DatePicker.mDelegate to the spinner delegate
                    delegateField.set(datePicker, delegate);

                    // Set up the DatePicker again, with the DatePickerSpinnerDelegate
                    datePicker.updateDate(year, month, dayOfMonth);
                }
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}

private Field findField(Class objectClass, Class fieldClass, String expectedName) {
    try {
        Field field = objectClass.getDeclaredField(expectedName);
        field.setAccessible(true);
        return field;
    } catch (NoSuchFieldException e) {
        Timber.i(e); // ignore
    }

    // search for it if it wasn't found under the expected ivar name
    for (Field searchField : objectClass.getDeclaredFields()) {
        if (searchField.getType() == fieldClass) {
            searchField.setAccessible(true);
            return searchField;
        }
    }
    return null;
}

It almost solve my problem. It look like spinner but number picker diplayed only on the half from the left side. How to center it?

It shows calendar view in API 25 in DatePickerDialog. How to make it spinner view. Also i want to hide "date" field from the spinner view in API 25.

Hello !! i am getting problem at if (mode == MODE_SPINNER) i debugged ,code not going inside this if .Please help.

To support Android [5.0, 6.0] just change line 33 to:

Class<?> spinnerDelegateClass;
try {
	// For android [5.0, 6.0], the DatePickerSpinnerDelegate is an inner class.
	spinnerDelegateClass = Class.forName("android.widget.DatePicker$DatePickerSpinnerDelegate");
} catch (ClassNotFoundException ignored) {
	// For android [7.0,), the DatePickerSpinnerDelegate is moved out to a normal class.
	spinnerDelegateClass = Class.forName("android.widget.DatePickerSpinnerDelegate");
}

Thanks to lognaturel and Noisyfox.
Here is the c# Xamarin version of this fix:

class NougatFixDatePickerDialog : DatePickerDialog
    {
        public NougatFixDatePickerDialog(Context context, IOnDateSetListener listener, int year, int month, int dayOfMonth) 
            : base(context, listener, year, month, dayOfMonth)
        {
            FixSpinner(context, year, month, dayOfMonth);
        }

        private void FixSpinner(Context context, int year, int month, int dayOfMonth)
        {
            try
            {
                const int modeSpinner = 1;
                Class styleableClass = Class.ForName("com.android.internal.R$styleable");
                Field datePickerStyleableField = styleableClass.GetField("DatePicker");
                int[] datePickerStyleable = (int[]) datePickerStyleableField.Get(null);
                TypedArray a = context.ObtainStyledAttributes(
                    null, datePickerStyleable, Android.Resource.Attribute.DatePickerStyle, 0);
                Field datePickerModeStyleableField = styleableClass.GetField("DatePicker_datePickerMode");
                int datePickerModeStyleable = datePickerModeStyleableField.GetInt(null);
                int mode = a.GetInt(datePickerModeStyleable, modeSpinner);
                a.Recycle();

                if (mode != modeSpinner)
                {
                    return;
                }

                DatePicker datePicker = (DatePicker) FindField(
                    Java.Lang.Class.FromType(typeof(DatePickerDialog)),
                    Java.Lang.Class.FromType(typeof(Android.Widget.DatePicker)), 
                    "mDatePicker").Get(this);

                Class delegateClass = Class.ForName("android.widget.DatePicker$DatePickerDelegate");
                Field delegateField = FindField(
                    Java.Lang.Class.FromType(typeof(Android.Widget.DatePicker)),
                    delegateClass, "mDelegate");
                Object jDelegate = delegateField.Get(datePicker);

                Class spinnerDelegateClass;
                try
                {
                    // For android [5.0, 6.0], the DatePickerSpinnerDelegate is an inner class.
                    spinnerDelegateClass = Class.ForName("android.widget.DatePicker$DatePickerSpinnerDelegate");
                }
                catch (ClassNotFoundException)
                {
                    // For android [7.0,), the DatePickerSpinnerDelegate is moved out to a normal class.
                    spinnerDelegateClass = Class.ForName("android.widget.DatePickerSpinnerDelegate");
                }

                if (delegateClass.Class == spinnerDelegateClass)
                {
                    return;
                }

                delegateField.Set(datePicker, null);
                datePicker.RemoveAllViews();

                Constructor spinnerDelegateConstructor = spinnerDelegateClass
                    .GetDeclaredConstructor(new Class[]
                    {
                        Class.FromType(typeof(Android.Widget.DatePicker)),
                        Java.Lang.Class.FromType(typeof(Android.Content.Context)),
                        Java.Lang.Class.FromType(typeof(IAttributeSet)),
                        Integer.Type,
                        Integer.Type
                    });
                spinnerDelegateConstructor.Accessible = true;
                    
                jDelegate.Dispose();
                jDelegate = spinnerDelegateConstructor
                    .NewInstance(datePicker, context, null, Android.Resource.Attribute.DatePickerStyle, 0);

                delegateField.Set(datePicker, jDelegate);
                datePicker.CalendarViewShown = false;
                datePicker.UpdateDate(year, month, dayOfMonth);
            }
            catch (Exception e)
            {
                Console.Out.Write(e.Message);
                throw e;
            }
        }

        private Field FindField(Class objectClass, Class fieldClass, string expectedName)
        {
            try
            {
                Field field = objectClass.GetDeclaredField(expectedName);
                field.Accessible = true;
                return field;
            }
            catch (NoSuchFieldException) { }

            // search for it if it wasn't found under the expected ivar name
            foreach (Field searchField in objectClass.GetDeclaredFields())
            {
                if (searchField.Type == fieldClass)
                {
                    searchField.Accessible = true;
                    return searchField;
                }
            }

            return null;
        }
    }