返回第一个元素时的ViewPager alpha动画

Question

问题是：有一个ViewPager具有相同类型的片段。有一个Spinner，其中包含一个值列表，选中后，替换所有片段的内容并移动到1个片段。是否可以在从列表中选择值时添加ViewPager的alpha动画，然后选择第一个片段？试图这样做，但动画总是笨拙地调用，并且它会多次出现。

ActivityViewPager

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ActivityCompat.postponeEnterTransition(this);
    setContentView(R.layout.activity_treining_info);
    if (getIntent().hasExtra(ClassTraining.KEY_TR_TYPE)) {
        type = getIntent().getIntExtra(ClassTr.KEY_TR_TYPE, 1);
        lvl = getIntent().getIntExtra(ClassTr.KEY_TR_LVL, 1);
    }
    animation = new AnimationClass(this);
    dataRes=DataResCompound.getInstance();
    clInfo = (ConstraintLayout)findViewById(R.id.cl_info);
    initPagerAdapter();
    initSpinner();
}

private void initPagerAdapter() {
    pager = (ViewPager) findViewById(R.id.pager);
    pagerAdapter = new MyFragmentPagerAdapter(getSupportFragmentManager());
    pager.setAdapter(pagerAdapter);
    pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {

    @Override
    public void onPageSelected(int position) {
        lvl = position+1;
    }

    @Override
    public void onPageScrolled(int position, float positionOffset,
          int positionOffsetPixels) {
    }

      @Override
      public void onPageScrollStateChanged(int state) {
      }
    });
    pager.setCurrentItem(lvl-1);
}



private void initSpinner() {
    final int[] size1 = {0};
    //ArrayAdapter adapter = ArrayAdapter.createFromResource(this, R.array.trainings, R.layout.spiner_layout);
    spnTrain = (Spinner)findViewById(R.id.spn_train);
    ArrayAdapter adapter = ArrayAdapter.createFromResource(this, R.array.trainings, android.R.layout.simple_spinner_dropdown_item);
    spnTrain.setAdapter(adapter);
    spnTrain.setSelection(type-1);
    spnTrain.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            if(isStart>0) {
                lvl = 1;
                type=position+1;
                getSupportFragmentManager().getFragments().clear();
                pagerAdapter.notifyDataSetChanged();
                alphaViewTraining();
            }
            isStart++;
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
        }
    });
}

private void alphaViewTraining(){
    clInfo.startAnimation(animation.getAlphaAnimation(pager, clInfo, 2, lvl-1));  } private class MyFragmentPagerAdapter extends FragmentPagerAdapter {

    public MyFragmentPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        return FragmentPageTrainInfo.newInstance(typeTrening, position+1);
    }

    @Override
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }

    @Override
    public int getCount() {
        return PAGE_COUNT;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        int lvl=position+1;
        return "Уровень " + lvl;
    }
}

AnimationClass

public Animation getAlphaAnimation(View _view, final View layout, final int typeView, Object _value){
view=_view;
value=_value;

in = AnimationUtils.loadAnimation(context,  R.anim.alpha_in);
out = AnimationUtils.loadAnimation(context, R.anim.alpha_out);

out.setAnimationListener(new Animation.AnimationListener() {

    @Override
    public void onAnimationStart(Animation animation) {

    }

    @Override
    public void onAnimationEnd(Animation animation) {
        setValueToView(view, layout, value, typeView);
    }

    @Override
    public void onAnimationRepeat(Animation animation) {

    }
});
return out;}private void setValueToView(View view, View layout, Object value, int typeView){
((ViewPager)view).setCurrentItem((int)value);
layout.startAnimation(in);
break;
view.startAnimation(in);}

在我看来，这是一个重叠标准动画ViewPager和我的问题。是否提示可以制作一些东西？