Problem with animation in Android Studio

Question

I created a Float Buttom to start an animation, but when I click on it, the animation does not occur. I have already done the debug to check the method that starts the animation and it occurs normally. I believe it may be some XML problem.

the XML of the animation:

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:interpolator="@android:anim/accelerate_decelerate_interpolator">

    <alpha
        android:fromAlpha="0.0"
        android:toAlpha="1.0"
        android:duration="2000" >
    </alpha>

</set>

The Listener of Float Buttom in Main Activity:

botaoAjuda.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Animation animation = AnimationUtils.loadAnimation(MainActivity.this,
                R.anim.tutorialanim);
        animation.start();
        Log.d("anim: ",animation+"");
    }
});

and that Float Buttom is in a layout that I call on layout of Main Activity with include:

<android.support.design.widget.FloatingActionButton
    android:id="@+id/helpButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    android:foregroundGravity="bottom"
    app:fabSize="normal"
    app:layout_anchor="@+id/include"
    app:layout_anchorGravity="bottom|right" />

The include na Main Activity:

<include
    layout="@layout/app_bar_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Answer 1

Instead of:

animation.start();

you must use:

botaoAjuda.startAnimation(animation);

Note that you did not assign any animation to the button, simply created a variable of type Animation within it.

Answer 2

The problem is that your animation is not applied to any View, except in itself, which is not a view.

When you create an animation via XML, your goal is to animate some view belonging to your layout, and this will not occur if you do not point your animation to any of them.

Behold:

Animation animation = AnimationUtils.loadAnimation(MainActivity.this,
            R.anim.tutorialanim);

ImageView mView = (ImageView) findViewById(R.id.view22);
mView.startAnimation(animation); // uma view qualquer definida no seu layout