从动态片段中设置选项卡标题

我有一个活动(MainActivity),它有五个选项卡,每个选项卡包含一个片段。每个片段包含一个 EditText 小装置。当我在活动片段的类中更改EditText的文本时,我想设置活动选项卡的标题。我怎么能在飞行中做到?

主要活动:

public class MainActivity extends AppCompatActivity {
    private SectionsPagerAdapter mSectionsPagerAdapter;
    private ViewPager mViewPager;

    ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);

        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

第PAGERADAPTER节:

public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        switch (position){
            case 0:
                Tab1 tab1 = new Tab1();
                return tab1;
            case 1:
                Tab2 tab2 = new Tab2();
                return tab2;
            case 2:
                Tab3 tab3 = new Tab3();
                return tab3;
            case 3:
                Tab4 tab4 = new Tab4();
                return tab4;
            case 4:
                Tab5 tab5 = new Tab5();
                return tab5;
            default:
                return null;
        }
    }

    @Override
    public int getCount() {
        // Show 5 total pages.
        return 5;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return "title1";
            case 1:
                return "title2";
            case 2:
                return "title3";
            case 3:
                return "title4";
            case 4:
                return "title5";
        }
        return null;
    }
}

表1:

public class Tab1 extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.tab1, container, false);
        return rootView;
    }
}

编辑文本 在Tab1上,我开始键入,它将第一个选项卡的标题从“title1”更改为我键入的字符串。