调整Fragment中TextView的文本大小

如何更改fragment中TextView的文本大小。我需要这样做，因为文本大小很小，可能有些用户希望它变大一些。

我看到有些人建议使用seekbar或者捏合缩放，但是我无法在fragment中使其工作。

谢谢您的帮助。

我的fragment_one.xml:

这是我的OneFragment.java:

public class OneFragment extends Fragment {
    public OneFragment() {
        // Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_one, container, false);
        return rootView;
    }
}

这是我的activity:

public class SimpleTabsActivity extends AppCompatActivity {
    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_simple_tabs);
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(false);
        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);
        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
    }
    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new OneFragment(), "tab1");
        adapter.addFragment(new TwoFragment(), "tab2");
        viewPager.setAdapter(adapter);
    }
    static class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List mFragmentList = new ArrayList<>();
        private final List mFragmentTitleList = new ArrayList<>();
        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }
        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }
        @Override
        public int getCount() {
            return mFragmentList.size();
        }
        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }
        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()){
            case R.id.aboutMenuItem:
                Intent i = new Intent(this, About_Activity.class);
                startActivity(i);
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}