Question

我正在尝试学习数据绑定，我有一个Sub Array_Example() Dim India As String Dim Australia As String Dim Singapore As String Dim Russia As String Dim Malaysia As String End Sub类，它按照如下方式绑定在我的CreditCardViewModel中

fragment

}

public class CreditCardValidatorFragment extends Fragment {

private CreditCardViewModel cardViewModel;
private CcValidateFragmentBinding binding;

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
                         @Nullable Bundle savedInstanceState) {
    binding = DataBindingUtil.inflate(inflater, R.layout.cc_validate_fragment, container, false);
    return binding.getRoot();
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    cardViewModel = ViewModelProviders.of(this).get(CreditCardViewModel.class);
    binding.setCreditCardViewModel(cardViewModel);
    binding.submitButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Navigation.findNavController(view).navigate(CreditCardValidatorFragmentDirections.actionMainFragmentToSecondFragment("Arvinder"));
        }
    });
    //required to update UI with Live data
    binding.setLifecycleOwner(this);

}

我的部分布局

public class CreditCardViewModel extends ViewModel {
private MutableLiveData<String> firstName = new MutableLiveData<>();
private MutableLiveData<String> lastName = new MutableLiveData<>();
private MutableLiveData<Long> ccNumber = new MutableLiveData<>();
private MutableLiveData<Integer> ccType = new MutableLiveData<>();
private MutableLiveData<String> exp = new MutableLiveData<>();
private MutableLiveData<Integer> cvv = new MutableLiveData<>();

public String getFirstName() {
    return firstName.getValue();
}

public String getLastName() {
    return lastName.getValue();
}

public Long getCcNumber() {
    return ccNumber.getValue().longValue();
}

public Integer getCcType() {
    return ccType.getValue();
}

public String getExp() {
    return exp.getValue();
}

public Integer getCvv() {
    return cvv.getValue();
}

public void onCvvTextChanged(CharSequence text) {
    cvv.setValue(Integer.valueOf(text.toString()));
}

public void onFirstNameChanged(CharSequence text) {
    firstName.setValue(text.toString());
}

public void onLastNameChanged(CharSequence text) {
    lastName.setValue(text.toString());
}

public void onCCNumberChanged(CharSequence text) {
    ccNumber.setValue(Long.valueOf(text.toString()));
}

public void onExpChanged(CharSequence text) {
    exp.setValue(text.toString());
}

public void onCCTypeChanged(CharSequence text) {
    ccType.setValue(Integer.valueOf(text.toString()));
}
}

尝试在版式中设置cvv时收到以下错误：

<EditText
            android:id="@+id/cvvEdit"
            android:layout_width="wrap_content"
            android:layout_height="48dp"
            android:layout_marginStart="36dp"
            android:layout_marginLeft="36dp"
            android:layout_marginTop="24dp"
            android:afterTextChanged="@{(text) -> creditCardViewModel.onCvvTextChanged(text)}"
            android:ems="10"
            android:inputType="number"
            android:text="@={creditCardViewModel.cvv}"
            app:layout_constraintStart_toEndOf="@+id/cvv"
            app:layout_constraintTop_toBottomOf="@+id/expirationEdit" />

表达式android:text="@={creditCardViewModel.cvv}"不能反转，因此不能用于双向绑定

详细信息：双向绑定无法解析creditCardViewModel.getCvv()属性java.lang.Integer的设置器

我试图在cvv中添加getter和setter来正确获取属性，但仍然会收到错误消息。

Answer 1

将其作为您的私有变量在ViewModel中公开

public MutableLiveData<String> firstName = new MutableLiveData<>();
public MutableLiveData<String> lastName = new MutableLiveData<>();
public MutableLiveData<Long> ccNumber = new MutableLiveData<>();
public MutableLiveData<Integer> ccType = new MutableLiveData<>();
public MutableLiveData<String> exp = new MutableLiveData<>();
public MutableLiveData<Integer> cvv = new MutableLiveData<>();

并且您必须将整数转换为字符串

android:text="@={String.valueOf(creditCardViewModel.cvv)}"

双向绑定无法解析setter

1 个答案: