How to change spinner text size and text color?

Simple and crisp...:

private OnItemSelectedListener OnCatSpinnerCL = new AdapterView.OnItemSelectedListener() {
    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {

       ((TextView) parent.getChildAt(0)).setTextColor(Color.BLUE);
       ((TextView) parent.getChildAt(0)).setTextSize(5);

    }

    public void onNothingSelected(AdapterView<?> parent) {

    }
};

Make a custom XML file for your spinner item.

spinner_item.xml:

Give your customized color and size to text in this file.

<?xml version="1.0" encoding="utf-8"?>

<TextView  
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" 
    android:layout_height="wrap_content"
    android:textSize="20sp"
    android:gravity="left"  
    android:textColor="#FF0000"         
    android:padding="5dip"
    />

Now use this file to show your spinner items like:

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.spinner_item,list);

You don't need to set the drop down resource. It will take spinner_item.xml only to show your items in spinner.