protected final void setAlpha(final float alpha) {
        Condition.INSTANCE.ensureAtLeast(alpha, 0, "The alpha must be at least 0");
        Condition.INSTANCE.ensureAtMaximum(alpha, 1, "The alpha must be at maximum 1");
        this.alpha = alpha;
    }
protected final void setAlpha ( final float alpha ) { Condition . INSTANCE . ensureAtLeast ( alpha , 0 , "The alpha must be at least 0" ) ; Condition . INSTANCE . ensureAtMaximum ( alpha , 1 , "The alpha must be at maximum 1" ) ; this . alpha = alpha ; }
Sets the alpha, which should be used by the animation.

@param alpha
The alpha, which should be set, as a {@link Float} value. The alpha must be at least
0 and at maximum 1