如何在Android的ViewModel类DataBinding中获取R.string

Question

I am currently using databinding for my android application project. I want to set the error message on my CustomTextView from R.string.txtOldPassWordError and set it up from another class called ViewModelClass .

Here is my XML code

<com.horseproject.widget.CustomEditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center_vertical"
    android:layout_marginTop="@dimen/dp_20"
    android:drawablePadding="@dimen/dp_10"
    android:hint="@string/enter_old_password"
    android:inputType="textPassword"
    android:lines="1"
    android:text="@={ChangePasswordVM.userOldPassword}"
    android:textColorHint="@color/gray_text"
    app:drawableLeftCompat="@drawable/ic_password_lock"
    app:drawableTintCompat="@color/gray_app"
    app:error="@{ChangePasswordVM.userOldPasswordError}" />

and this is ViewModelClass.java

public class ChangePasswordViewModel extends BaseObservable {

    public ObservableField<String> userOldPassword = new ObservableField<>("");

    public void userPasswordChange() {

        if ((TextUtils.isEmpty(userOldPassword.get()))) {
            userOldPasswordError.set("Please enter your old password");
            return;
        } else if (userOldPassword.get().length() <= 5) {
            userOldPasswordError.set("Password should contain minimum 6 characters");
            return;
        } else {
            userOldPasswordError.set(null);
        }
    }
}

and this is string from strings.xml

<string name="select">Please Enter Old Password</string>

So, I want to access this string in my viewModel class and set it as error message instead of hardcoded it directly as string .

So how can i achieve this? I am using Android Studio 3.0 Beta Version. Any help would be really appreciated.

Answer 1

Using an ObservableInt worked for me. Adding this to the ViewModel

private final ObservableInt mErrorText = new ObservableInt(R.string.empty_text);

public ObservableInt getErrorText() {
   return mErrorText;
}

And just setting a new String value

mErrorText.set(R.string.text_not_valid);

In the xml add the following to the TextView

android:text="@{viewModel.errorText}"

Answer 2

Create ResourceProvider class

public class ResourceProvider {

    private Context mContext;

    public ResourceProvider(Context mContext) {
        this.mContext = mContext;
    }

    public String getString(int resId) {
        return mContext.getString(resId);
    }

    public String getString(int resId, String value) {
        return mContext.getString(resId, value);
    }
}

now go to your ApplicationClass and paste

public class YourAppName extends Application {
  // Resource Provider
    private ResourceProvider mResourceProvider;
    public ResourceProvider getResourceProvider() {
        if (mResourceProvider == null)
            mResourceProvider = new ResourceProvider(this);

        return mResourceProvider;
    }
}

now go to your ChangePasswordViewModel and create object of ResourceProvider

private ResourceProvider mResourceProvider;

and pass it in constroctor of ChangePasswordViewModel

than you can access it by

 userOldPasswordError.set(mResourceProvider.getString(R.string.select));

Answer 3

You can send context into the layout like this :

XML :

<!-- 
<data>
     <variable 
          name="observable"
          type="...MyBaseObservableClass"
     />
</data>
 -->

android:text="@{observable.getDescription(context)}"

MyBaseObservableClass.kt :

@Bindable
fun getDescription(context: Context): String {
    return context.getString(R.string.my_string)
}

fun setNewData(data: Object) {
     this.data = data
     notifyPropertyChanged(BR.description)
}