This is a demo app to show how to incrementally implement data binding in an Android app.
It starts from a branch without any data binding for each step would be represented by a new branch.

0-no-databinding
1-minimal-setup
2-viewbinding
3-oneway-data-binding
4-view-binding-expression
5-binding-adapters
6-persistent-data-binding
7-event-listeners
8-twoway-data-binding

The code is commented on the full-databinding branch only.
Here are explanations and comparisons for each branch:

To activate data binding, you need to set at least 3 things.

1. enable data binding inside the gradle config file.
2. wrap your layouts with a simple <layout>.
3. use the DataBindingUtil class to inflate your layout inside your activity/fragment

See the changed code here: https://github.com/oldergod/DataBindingDemo/compare/0-no-databinding...1-minimal-setup

With data binding activated, you can know access directly your layout views using the binding object returned from the layout inflation.
It is type safe, you are sure you did not make mistakes setting the @id and it also works with included layouts.

See the changed code here: https://github.com/oldergod/DataBindingDemo/compare/1-minimal-setup...2-viewbinding

Let's pass an object to our layout so every view is automatically filled with its corresponding data. We do not need to view.setText() anything anymore.
No more Null Pointer Exception! We can use resources, and some logic.

See the changed code here: https://github.com/oldergod/DataBindingDemo/compare/2-viewbinding...3-oneway-data-binding

We the use of the @{} operation, we can use java code inside the XML to add logic to our UI behavior. I.e. set a view visibility based the view model, or reuse dimensions.

See the changed code here: https://github.com/oldergod/DataBindingDemo/compare/3-oneway-data-binding...4-view-binding-expression

Here, we create a data binding adapter that would allow us to use a custom xml attribute that would use our drawableId and use it to set an image view.

See the changed code here: https://github.com/oldergod/DataBindingDemo/compare/4-view-binding-expression...5-binding-adapters

We use observable to allow our UI to be automatically updated when the view model changes.

See the changed code here: https://github.com/oldergod/DataBindingDemo/compare/5-binding-adapters...6-persistent-data-binding

We bind the BottomNavigationView and CheckBox event listeners in our binding adapter so we can set what function will be called on the corresponding events without boilerplate in our activity.

See the changed code here: https://github.com/oldergod/DataBindingDemo/compare/6-persistent-data-binding...7-event-listeners

We transform @{} to @={} to activate two way data binding. In our case, we use it so our view model is updated everytime the checkbox is ticked and we do not need any listener anymore to do it manually.

See the changed code here: https://github.com/oldergod/DataBindingDemo/compare/7-event-listeners...8-twoway-data-binding

The code contains some overkills (like binding methods when not really needed) to display the available features.
Also this does not represent all the features of the data binding library. Check the doc for more info: https://developer.android.com/topic/libraries/data-binding/index.html

Copyright 2016 Benoit Quenaudon

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.