我使用的5个不同的片段一TabLayout。在3这些片段的 android.support.design.widget.FloatingActionButton 应该出现。现在，我只需设定FAB的标签发生变化时的可见度，但我想有一个动画，其中FAB进来和出去。 我怎样才能在Android中实现这一目标？

I am using a TabLayout with 5 different fragments. On 3 of these fragments a android.support.design.widget.FloatingActionButton should appear. Right now I simply set the visibility of the FAB when the tab changes, but I would like to have an animation, where the FAB comes in and out. How can I achieve this in Android?

推荐答案

由于我不想延长 FloatingActionButton ，我做了这种方式：

Because I did not want to extend the FloatingActionButton, I made it this way:

FloatingActionButton createButton;

// ...

Animation makeInAnimation = AnimationUtils.makeInAnimation(getBaseContext(), false);
makeInAnimation.setAnimationListener(new Animation.AnimationListener() {
    @Override
    public void onAnimationEnd(Animation animation) { }

    @Override
    public void onAnimationRepeat(Animation animation) { }

    @Override
    public void onAnimationStart(Animation animation) {
        createButton.setVisibility(View.VISIBLE);
    }
});

Animation makeOutAnimation = AnimationUtils.makeOutAnimation(getBaseContext(), true);
makeOutAnimation.setAnimationListener(new Animation.AnimationListener() {
    @Override
    public void onAnimationEnd(Animation animation) {
        createButton.setVisibility(View.INVISIBLE);
    }

    @Override
    public void onAnimationRepeat(Animation animation) { }

    @Override
    public void onAnimationStart(Animation animation) { }
});

// ...

if (createButton.isShown()) {
    createButton.startAnimation(makeOutAnimation);
}

// ...

if (!createButton.isShown()) {
    createButton.startAnimation(makeInAnimation);
}