I have seen the DataBindingComponent in the official API doc.
https://developer.android.com/reference/android/databinding/DataBindingUtil.html
This interface is generated during compilation to contain getters for all used instance BindingAdapters. When a BindingAdapter is an instance method, an instance of the class implementing the method must be instantiated. This interface will be generated with a getter for each class with the name get* where * is simple class name of the declaring BindingAdapter class/interface. Name collisions will be resolved by adding a numeric suffix to the getter.
An instance of this class may also be passed into static or instance BindingAdapters as the first parameter.
If using Dagger 2, the developer should extend this interface and annotate the extended interface as a Component.
However, I cannot find any example usage of this class in the web. Can anyone know what it is and how to use it.
I tried to make some simple code and debug it to see what's is it but it showed null variable on the a
variable.
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ActivityMainBinding binding= DataBindingUtil.setContentView(this,R.layout.activity_main); android.databinding.DataBindingComponent a = DataBindingUtil.getDefaultComponent(); setContentView(binding.getRoot()); }
Returns the binding for the given layout root or creates a binding if one does not exist. Prefer using the generated Binding's bind method to ensure type-safe inflation when it is known that root has not yet been bound. View : The root View of the inflated binding layout.
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Data Binding allows you to effortlessly communicate across views and data sources. This pattern is important for many Android designs, including model view ViewModel (MVVM), which is currently one of the most common Android architecture patterns.
In Android, the Data Binding Library is a support library that allows you to bind UI components in your layouts to data sources in your app using a declarative format rather than programmatically.
After reading the answer from @tynn , the DataBindingComponent class can also be as "object" scope of data binding method. Instead of setting all the method in static way, the following example can be used to be extendable and custom. For example, we setup 3 binding methods for ImageView, TextView and View type. You can setup the interface first ( like Retrofit 2 setup interface for API)
1. Setup 3 interface first
ImageViewBindingInterface.java
public interface ImageViewBindingInterface { @BindingAdapter({"bind:imageUrl", "bind:error"}) public void loadImage(ImageView view, String url, Drawable error); }
TextViewBindingInterface.java
public interface TextViewBindingInterface { @BindingAdapter({"bind:font"}) void setFont(TextView textView, String fontName); }
ViewBindingInterface.java
public interface ViewBindingInterface { @BindingAdapter("android:paddingLeft") public void setPaddingLeft(View view, int padding); @BindingAdapter("android:onViewAttachedToWindow") public void setListener(View view, ViewBindingAdapter.OnViewAttachedToWindow attached); }
2. The DataBindingComponent.java should be updated automatically as @tynn mentioned like the following.
If you have a look at the default DataBindingComponent class in Android Studio you find it located in build/generated/source/apt/dev.
public interface DataBindingComponent { example.com.testerapplication.binding.ViewBindingInterface getViewBindingInterface(); example.com.testerapplication.binding.TextViewBindingInterface getTextViewBindingInterface(); example.com.testerapplication.binding.ImageViewBindingInterface getImageViewBindingInterface(); }
3. Build your own implementation method for binding.
BaseImageViewBinding.java
public class BaseImageViewBinding implements ImageViewBindingInterface{ @Override public void loadImage(ImageView view, String url, Drawable error) { Picasso.with(view.getContext()).load(url).error(error).into(view); } }
BaseTextViewBinding.java
public class BaseTextViewBinding implements TextViewBindingInterface { @Override public void setFont(TextView textView, String fontName) { textView.setTypeface(Typeface.createFromAsset(textView.getContext().getAssets(), "fonts/" + fontName)); } }
BaseViewBinding.java
public class BaseViewBinding implements ViewBindingInterface { @Override public void setPaddingLeft(View view, int padding) { view.setPadding(padding, view.getPaddingTop(), view.getPaddingRight(), view.getPaddingBottom()); } @Override public void setListener(View view, ViewBindingAdapter.OnViewAttachedToWindow attached) { } }
4. Set your OwnDatabindingComponent
public class MyOwnDefaultDataBindingComponent implements android.databinding.DataBindingComponent { @Override public ViewBindingInterface getViewBindingInterface() { return new BaseViewBinding(); } @Override public TextViewBindingInterface getTextViewBindingInterface() { return new BaseTextViewBinding(); } @Override public ImageViewBindingInterface getImageViewBindingInterface() { return new BaseImageViewBinding(); } }
5. Setup your default DataBindingComponent in the Application
public class MyApplication extends Application { public void onCreate() { super.onCreate(); DataBindingUtil.setDefaultComponent(new MyOwnDefaultDataBindingComponent()); } }
Using this method should be fine to make the custom data binding in a custom way and can be extensible.
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