使用数据绑定时，Android EditText未更新

Question

EditText应包含文本"电子邮件地址"。一旦用户按下EditText字段，它就会被清除，这样用户就可以填写他的真实电子邮件地址。

使用"Build"、"Rebuild project"进行更改，以确保正确地重新加载数据绑定。

主要活动

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    final LoginActivityBinding binding = DataBindingUtil.setContentView(this, R.layout.login_activity);
    binding.userEmail.setText("E-mail address");
    binding.setViewmodel(new LoginViewModel(new LoginDataListener() {
        @Override
        public void onLoginClicked() {
            String userEmail = binding.userEmail.getText().toString();
            User user = new User(userEmail, "");
        }
    }));
}

LoginViewModel

public class LoginViewModel {
    private LoginDataListener mDataListener;
    public LoginViewModel(@NonNull final LoginDataListener loginDataListener) {
        mDataListener = loginDataListener;
    }
    public void onLoginClicked(View view){
        mDataListener.onLoginClicked();
    }
    public void onEmailAddressClicked(View view) {
        EditText userEmail = (EditText) view.findViewById(R.id.user_email);
        userEmail.setText("");
    }

login_activity.xml

<EditText
    android:id="@+id/user_email"
    android:onClick="@{viewmodel::onEmailAddressClicked}"
    android:text="@={user.email}"
    android:inputType="textEmailAddress"
    android:layout_gravity="center_horizontal" />
<Button
    android:id="@+id/login_button"
    android:onClick="@{viewmodel::onLoginClicked}"
    android:text="@string/login"
    android:layout_gravity="center_horizontal" />

用户

public class User {
    private String email;
    public User(String email) {
        this.email = email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getEmail() {
        return email;
    }    
}

Answer 1

您在这里做错了：

binding.userEmail.setText("E-mail address");

Do：

User user = new User("E-mail address");
binding.setUser(user);

但是，为什么不将文本提示设置为Edittext以满足您的要求呢？