Items in the drop down list of AutoCompleteTextView are not visible. How to change their color..?

For controlling the way you display items in your autocomplete view, you have to set the textViewResourceId in your adapter. You can use the ArrayAdapter and give android.R.layout.simple_dropdown_item_1line as the textViewResourceId as shown below.

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_dropdown_item_1line, yourList);
AutoCompleteTextView autocompleteView = (AutoCompleteTextView) findViewById(R.id.autocomplete_box);
autocompleteView.setAdapter(adapter);

OR

if you want to create your own style for the items displayed, please create an XML with TextView as the root element like this (lets name it my_custom_dropdown.xml with black color text and white background)

<?xml version="1.0" encoding="utf-8"?>
<TextView 
    xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" 
    android:textSize="20sp" 
    android:padding="5sp"
    android:textColor="@color/black"
    android:background="@color/white"/>

Then refer to the xml in your adapter as below -

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.my_custom_dropdown, yourList);

Just to point out that by using android.R.layout.simple_dropdown_item_1line it will give you the same issue you encountered above. So you're better off just creating your own TextView in an .xml file.

If changing code from "android.R.layout.simple_list_item_1" to "android.R.layout.simple_dropdown_item_1line" didn't work for you,

you should try to write this code before setContentView

setTheme(android.R.style.Theme);

It worked for me :)