NaveenDevrani/DataBindingDemo

Learn How to use Databinding in android

One way and Two way DataBinding

Overview

Android has now released a stable data-binding library which allows you to connect views with data in a much more powerful way than was possible previously. Applying data binding can improve your app by removing boilerplate for data-driven UI and allowing for two-way binding between views and data objects.

Getting Started

Add the following code in your app’s build.gradle.

android  {   
        dataBinding {  
            enabled = true  
         }  
     }  

Layouts and binding expressions

The expression language allows you to write expressions that connect variables to the views in the layout. The Data Binding Library automatically generates the classes required to bind the views in the layout with your data objects.

For example, the binding variables that can be used in expressions are defined inside a data element that is a sibling of the UI layout's root element. Both elements are wrapped in a layout tag, as shown in the following example:

<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable
            name="viewmodel"
            type="com.myapp.data.ViewModel" />
    </data>
    <ConstraintLayout... /> 
</layout>
 

The layout for each row of the RecyclerView is defined in item_row.xml.

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable
            name="model"
            type="com.journaldev.androidrecyclerviewdatabinding.DataModel" />
        <variable
            name="itemClickListener"
            type="com.journaldev.androidrecyclerviewdatabinding.CustomClickListener" />
    </data>
    <your adapter view></your adapter view>
    </layout>

#Best Practices

<TextView   
    android:visibility="@{post.hasComments ? View.Visible : View.Gone}" />

 @BindingAdapter({"isVisible"})  
  public static void setIsVisible(View view, boolean isVisible) {
      if (isVislble) {
        view.visibility = View.VISIBLE
      } else {
        view.visibility = View.GONE
      }
  }
  
  <TextView 
    app:isVisible="@{post.hasComments()}" />

Result