DataBindingExample

A demo of how to implement Data Binding in Android app</br></br>

Each Activity in the demo app shows a sample implementation of data binding.<br/>

<h4>Replace findViewById with data binding</h4>

Step 1: In layout file, make <layout> tag as most parent tag or root tag. After adding it, build system will process it for data binding.<br/> Step 2: After above step, binding class will be generated based on same name of layout file (e.g. activity_main’s binding class will be generated as ActivityMainBinding). Set setContentView using DataBindingUtil.<br/> That’s it.<br/> Example: DataBinding1Activity<br/><br/>

<h4>How can we change binding class name?</h4>

By default, binding class is generated based on the name of the layout file and placed in a data binding package under the module package. E.g. the layout file activity_main.xml will generate ActivityMainBinding. If the module package is com.an.demo, then it will be placed in com.an.demo.databinding directory.<br/> We can change that by adding this tag <data class="MainActivityBinding"> to the layout file.<br/>Now generated binding class is named MainActivityBinding<br/> That’s it.<br/> Example: DataBinding2Activity<br/><br/>

<h4>How to bind data in layout file?</h4>

Step 1: Create a POJO class i.e. User<br/> Step 2: Add <data> element to the layout file. <data> element is a way to binding data with UI element.<br/> Step 3: Add <variable> element to the layout file. <variable> is a object of POJO which we bind with UI.<br/> Step 4: add @{user.name} in text property of TextView. Generally, Expressions within the layout are written in the attribute properties using the @{} syntax<br/> Step 4: Set binding.setUser(user); in the Activity class<br/> That’s it.<br/> Example: DataBinding2Activity<br/><br/>

<h4>Event Handling using data binding</h4>

Step 1: In layout file, make <layout> tag as most parent tag or root tag.<br/> Step 2: After above step, binding class will be generated based on same name of layout file (e.g. activity_main’s binding class will be generated as ActivityMainBinding). Set setContentView using DataBindingUtil.<br/> Step 3: Create a POJO class i.e. LoginModel and add it as a variable to the layout file.<br/> Step 4: Create a presenter class i.e. LoginPresenter and add it as a variable to the layout file.<br/> Step 5: android:onClick="@{presenter::onClickButton2}" is an example of event binding with Method reference That’s it.<br/> Example: MainActivity<br/><br/>

<h4>Custom Data Binding Implementation</h4>

Step 1: In layout file, make <layout> tag as most parent tag or root tag. Create a POJO class i.e. LoginModel and add it as a variable to the layout file. i.e. LoginModel. Create a presenter class and add it as a variable to the layout file. i.e. LoginPresenter<br/> Step 2: Create a separate adapter class for Binding i.e. DataBindingAdapter. Functionality of the custom binding class would be to display a Toast message. Create the binding method inside the customer adapter class.i.e.<br/>

    public static void showToast(View view, String toast) {
       if(toast != null && !toast.isEmpty()) {
           Toast.makeText(view.getContext(), toast, Toast.LENGTH_SHORT).show();
       }
   }

Add the custom attribute to your view in the layout file.i.e. app:toast="@{loginInfo.loginMessage}" <br/> Step 3: Set binding.setModel(new LoginModel()); in the Activity class.<br/> Step 4: Set binding.setPresenter(new LoginPresenter()); in the Activity class.<br/> That’s it.<br/> Example: DataBinding3Activity<br/><br/>

<h4>Implement RecyclerView using Data Binding</h4>

Step 1: In layout file, make <layout> tag as most parent tag or root tag. <br/> Step 2: Create a custom BindingViewHolder class for reusability purposes.<br/> Step 3: Create your recyclerview adapter class and item layout class. Set data & variable tag to the layout item class.<br/> Step 4: Set binding.recyclerView.setAdapter(adapter); to the Activity class <br/> That’s it.<br/> Example: DataBinding4Activity<br/><br/>

DataBindingExample

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README

DataBindingExample