无法从方法更改片段文本视图

Question

我正在尝试使用这种简单的方法来更改片段文本视图，但每次我尝试使用此片段代码

打开片段的 activity 时，应用程序都会崩溃

public class FragmentContrat extends Fragment {
    public FragmentContrat() {}

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.contrat_fragment, container, false);
        update();
        return view;

    }

    public void update() {
        TextView textView = (TextView)getView().findViewById(R.id.souscripteur_txt);
        textView.setText("milan");
    }

但是它工作正常，当我像这样在 onCreateView 中放置相同的代码时，TextView 发生了变化：

public class FragmentContrat extends Fragment {




    public FragmentContrat() {}


    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.contrat_fragment, container, false);
        TextView textView = (TextView)view.findViewById(R.id.souscripteur_txt);
        textView.setText("milan");
        return view;

    }

activity代码：

public class DetailsContrat extends AppCompatActivity {

    TabLayout details_tab;
    AppBarLayout details_bar;
    ViewPager details_pager;


protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_details_contrat);
        Intent i = getIntent();
        String client_id = i.getStringExtra("client_id");
        details_tab=(TabLayout)findViewById(R.id.details_tab);
        details_bar=(AppBarLayout) findViewById(R.id.details_bar);
        details_pager=(ViewPager)findViewById(R.id.details_pager);
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        FragmentContrat fragmentContrat = new FragmentContrat();
        FragmentVehicule fragmentVehicule = new FragmentVehicule();
        FragmentGaranties fragmentGaranties = new FragmentGaranties();



 adapter.AddFragment(fragmentContrat,"MON CONTRAT");
        adapter.AddFragment(fragmentVehicule,"MA VOITURE");
        adapter.AddFragment(fragmentGaranties,"MES GARANTIES");
        details_pager.setAdapter(adapter);
        details_tab.setupWithViewPager(details_pager);


    }



}

Answer 1

我认为你需要在更新方法中传递你的视图

public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.contrat_fragment, container, false);
    update(view);
    return view;

}

public void update(View view) {
    TextView textView = (TextView)view.findViewById(R.id.souscripteur_txt);
    textView.setText("milan");
}

Answer 2

在 onCreateView 中，您正在创建片段的视图。因此，如果您调用 getView() 来获取片段视图，您将得到 null，因为您尚未返回刚刚创建的视图。

您可以：

按照@Sanjaysinh 推荐的方式使用新创建的视图
避免在 onCreateView 中设置您的文本并在 onViewCreated(View view, Bundle savedInstanceState) 中设置它，即在创建视图后调用 (docs)

无法从方法更改片段文本视图

Can't change fragment text view from a method

android

textview

android-fragments