error: is incompatible with attribute : (attr) reference [weak]

Question

I am trying to integrate this library. I got an issue of "missing attributes", so I added these attributes to my project:

<?xml version="1.0" encoding="UTF-8"?>
<resources>
    <declare-styleable name="app">
        <attr name="isDone" format="boolean"/>
        <attr name="isVisible" format="boolean"/>
    </declare-styleable>
</resources>

After that I when I cleaned the project and run the build process again, I got this issue:

error: '@{viewModel.hasStartDate}' is incompatible with attribute com.example:isVisible (attr) reference [weak].
Message{kind=ERROR, text=error: '@{viewModel.hasStartDate}' is incompatible with attribute com.example:isVisible (attr) reference [weak]., sources=[/home/local/<USER_NAME>/.gradle/caches/transforms-1/files-1.1/DateTimeRangePicker-v1.3.aar/524561517fca999eba7db795be3a768d/res/layout/date_time_range_picker.xml:52], original message=, tool name=Optional.of(AAPT)}

At some places, one of which is this line in layout file generated by that library which used Data binding:

    app:isDone="@{viewModel.isCompletable}"

Inside the Kotlin code generated by that library, it is declared:

  val isCompletable = ObservableBoolean()

This library is in Kotlin. What is causing it?

Is it KAPT? Is it Data binding?

Answer 1

Declared attributes must be of the string type

    <attr name="isDone" format="string"/>
    <attr name="isVisible" format="string"/>

Answer 2

Xml layout

<android.support.design.widget.TextInputLayout
      android:layout_width=”match_parent”
      android:layout_height=”wrap_content”
      app:error=”@{loginInfo.passwordError}”>
      <EditText
        android:id=”@+id/password”
        android:layout_width=”match_parent”
        android:layout_height=”wrap_content”
        android:enabled=”@{loginInfo.existingUser}”
        android:hint=”@string/password”
        android:inputType=”textPassword”
        app:binding=”@{loginInfo.password}”/>
    </android.support.design.widget.TextInputLayout>

Model class

public class LoginInfo {
  public BindableBoolean existingUser = new BindableBoolean();
}

BindableBoolean class

import org.parceler.Parcel;

@Parcel
public class BindableBoolean extends BaseObservable {
    boolean mValue;

    public boolean get() {
        return mValue;
    }

    public void set(boolean value) {
        if (mValue != value) {
            this.mValue = value;
            notifyChange();
        }
    }
}