title: How to use method of object in Android data binding?
body: <p>Suppose I have this object:</p>
  
  <pre><code>public class Field
  {
     List&lt;String&gt; list;
     public Field()
     {
       list = new ArrayList();
     }
     public boolean isOnTheList(String someText)
     {
       return list.contains(someText);
     }
  }
  </code></pre>
  
  <p>Now I want to use this function on a xml with binding like this.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;layout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"&gt;
  
  &lt;data&gt;
  
      &lt;import type="android.view.View"/&gt;
  
      &lt;variable
          name="field"
          type="com.greendao.db.Field"/&gt;        
  
      &lt;variable
          name="user"
          type="com.package.User"/&gt;
  &lt;/data&gt;
  
  &lt;LinearLayout
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="horizontal"    
      android:visibility="@{field.isOnTheList(user.name)?View.VISIBLE:View.GONE}"
      tools:context=".advisor.new_visit_report.activities.FieldsSelectionActivity"&gt; ...
  </code></pre>
  
  <p>The problem is that is not working. Anyone has already tried this?            </p>