public class MainPagerAdapter extends FragmentPagerAdapter {

    private List<Fragment> fragmentList=new ArrayList<>();

    private List<String> fragmentTitle=new ArrayList<>();

    public MainPagerAdapter(@NonNull FragmentManager fm) {
        super(fm);
    }

    @Override
    public int getCount() {
        return fragmentList.size();
    }

    @NonNull
    @Override
    public Fragment getItem(int position) {
        return fragmentList.get(position);
    }

    public void addFragment(Fragment fragment,String title){
        fragmentList.add(fragment);
        fragmentTitle.add(title);
    }

     /**
     * 設置ViewPager的標題，可能之後可以寫一些判斷像是現在在哪個fragment之用
     */
    @Nullable
    @Override
    public CharSequence getPageTitle(int position) {
        return fragmentTitle.get(position);
    }
}