获取EditText的值应该在片段类中完成。为了从片段中获取EditText的值，应该从SwipeAdapter类中删除2个get方法，并将findViewById()调用放置在片段类中，如下所示：

public class EmailFieldFragment extends Fragment {

    private MainViewModel mainViewModel;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mainViewModel = new ViewModelProvider(requireActivity()).get(MainViewModel.class);
    }

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

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        // Do this after an action, example - after a button click
        EditText emailEt = view.findViewById(R.id.email_et);
        emailEt.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
               if (count < 1) { // i.e - no user input
                    mainViewModel.setEmail("");
                } else {
                    mainViewModel.setEmail(s.toString());
                }
            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });
    }
}

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我更新了SwipeAdapter以接受片段列表，如下所示：

public class SwipeAdapter extends FragmentStateAdapter {

    private final List<Fragment> fragments;

    public SwipeAdapter(@NonNull FragmentActivity fragmentActivity, 
    List<Fragment> fragmentList) {
        super(fragmentActivity);
        this.fragments = fragmentList;
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        return fragments.get(position);
    }

    @Override
    public int getItemCount() {
        return fragments.size();
    }
}

型
我创建了一个viewModel类，它保存LiveData对象中EditText字段的值。然后从活动（或片段）观察这些字段。代码如下：

public class MainViewModel extends ViewModel {
    private final MutableLiveData<String> _email = new 
    MutableLiveData<>();
    public LiveData<String> email = _email;

    private final MutableLiveData<String> _phone = new 
    MutableLiveData<>();
    public LiveData<String> phone = _phone;

    public void setEmail(String email) {
        _email.setValue(email);
    }

    public void setPhone(String phone) {
        _phone.setValue(phone);
    }
}

型
我还添加了生命周期依赖项。
最后，下面是Activity的代码：

public class MainActivity extends AppCompatActivity {

private String email = "";
private String phone = "";

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

    MainViewModel mainViewModel = new ViewModelProvider(this).get(MainViewModel.class);

    PhoneFieldFragment phoneFieldFragment = new PhoneFieldFragment();
    EmailFieldFragment emailFieldFragment = new EmailFieldFragment();
    List<Fragment> fragmentList = new ArrayList<>();
    fragmentList.add(phoneFieldFragment);
    fragmentList.add(emailFieldFragment);
    SwipeAdapter swipeAdapter = new SwipeAdapter(this, fragmentList);
    ViewPager2 viewPager = findViewById(R.id.viewPager);
    viewPager.setAdapter(swipeAdapter);

    Button button = findViewById(R.id.get_field_button);

    mainViewModel.email.observe(MainActivity.this, new Observer<String>() {
        @Override
        public void onChanged(String s) {
            email = s;
        }
    });

    mainViewModel.phone.observe(MainActivity.this, new Observer<String>() {
        @Override
        public void onChanged(String s) {
            phone = s;
        }
    });

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(MainActivity.this, "Email: " + email + "\nPhone: " + phone, Toast.LENGTH_SHORT).show();
            // Both email and phone number are available here, so you can call your setValue() method here
        }
    });
  }
}

型
This is a link to the entire codebase on github

编辑

我使用了一个共享的viewModel类，它连接viewPager片段和它们的主机Activity（或者根据具体情况连接另一个片段）。当用户使用TextWatcher输入时，我从EditText获取文本。

在你的Fragment代码中进行这些操作。这将是干净的，使维护容易。

更好的方法是使用SharedViewModel。

对我很有效

findViewById<AppCompatEditText>(R.id.notesET).apply {
        tag = position
        doAfterTextChanged {
            if (tag == position) {
                model.answer = "#$it"
            }
        }
    }

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