Android – Changing text color of menu item in navigation drawer

I'm trying to add a night theme for my app and I've wasted nearly three hours just trying to make the text and icons in my navigation drawer turn white along with the dark background. Here is the way I'm trying to go about doing this in onCreate() in MainActivity.java:

navigationView = (NavigationView) findViewById(R.id.navigation_view);
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {

    // This method will trigger onItemClick of navigation menu
    @Override
    public boolean onNavigationItemSelected(MenuItem menuItem) {

        // Checking if the item is in checked state or not, if not make it in checked state
        if (menuItem.isChecked())
            menuItem.setChecked(false);
        else menuItem.setChecked(true);

        if (nightMode == 0) {
            SpannableString spanString = new SpannableString(menuItem.getTitle().toString());
            spanString.setSpan(new ForegroundColorSpan(Color.WHITE), 0, spanString.length(), 0); // fix the color to white
            menuItem.setTitle(spanString);
        }

The nightMode boolean is irrelevant because it works. When night mode is set to on (0), whatever menu item is selected in the navigation drawer turns white. However, that only happens when each item is selected which is obviously inconvenient. Here is my drawer_dark.xml:

    <?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <group
        android:checkableBehavior="single">
        <item
            android:id="@+id/unitone"
            android:checked="true"
            android:icon="@drawable/one_white"
            android:title="Classical Period" />
        <item
            android:id="@+id/unittwo"
            android:checked="false"
            android:icon="@drawable/two_white"
            android:title="Postclassical Period" />
        <item
            android:id="@+id/unitthree"
            android:checked="false"
            android:icon="@drawable/three_white"
            android:title="Early Modern Era" />
        <item
            android:id="@+id/unitfour"
            android:checked="false"
            android:icon="@drawable/four_white"
            android:title="Dawn of Industrial Age" />
        <item
            android:id="@+id/unitfive"
            android:checked="false"
            android:icon="@drawable/five_white"
            android:title="Modern Era" />
    </group>
</menu>

I'm using white icons on a transparent background for each item, yet they show up as black on the black background of the navigation drawer. I've tried looking for an xml solution to changing the color of the text and I'm scratching my head because I don't know why this was overlooked.

Can someone offer me a dynamic solution in getting what I'm trying to achieve? All help is appreciated, thank you!

EDIT: I am not using a third party library, it's the NavigationView provided in the support library. Here's the XML layout:

<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/drawer"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:elevation="7dp"
    tools:context=".MainActivity"
    android:fitsSystemWindows="true" >

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <FrameLayout
            android:id="@+id/container"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/ColorDark" />

        <include layout="@layout/toolbar" />

    </FrameLayout>

    <android.support.design.widget.NavigationView
        android:id="@+id/navigation_view"
        android:background="#000"
        android:layout_height="match_parent"
        android:layout_width="match_parent"
        android:layout_gravity="start"
        app:headerLayout="@layout/header"
        app:menu="@menu/drawer" />

</android.support.v4.widget.DrawerLayout>