AndroidStudio onClick not triggered

I'm trying to cross-fade from one ImageView to another ImageView, using the onClick method. This is not a problem, but when I attempt to create an additional onClick method on the second image to cross-fade back, the initial imageView onClick does not trigger. Any ideas why this is?

Here is my xml code I'm using a relative layout and am just matching the ImageView to match both the width and height of the parent aka take up the whole screen.

Complete xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_main" tools:context=".MainActivity">

Image1

<ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/boobies"
        android:src="@drawable/niceboobs"
        android:onClick="fadeOut" />

Image2

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/nina"
        android:src="@drawable/ninasexy"
        android:alpha="0"
        android:onClick="fadeIn"/>

</RelativeLayout>

And these are my two onClick methods, I repeat when I just have the first method or second method they individually work but when I put them both only the second one works.

onClick method 1

  public void fadeOut(View view){

        ImageView boobs = (ImageView) findViewById(R.id.boobies);
        ImageView nina = (ImageView) findViewById(R.id.nina);

        boobs.animate().alpha(0f).setDuration(2000);
        nina.animate().alpha(1f).setDuration(2000);

    }

onClick method 2

    public void fadeIn(View view){


        ImageView boobs = (ImageView) findViewById(R.id.boobies);
        ImageView nina = (ImageView) findViewById(R.id.nina);

        boobs.animate().alpha(1f).setDuration(2000);
        nina.animate().alpha(0f).setDuration(2000);

    }