BindingAdapter

public abstract @interface BindingAdapter
implements Annotation

android.databinding.BindingAdapter

BindingAdapter is applied to methods that are used to manipulate how values with expressions are set to views. The simplest example is to have a public static method that takes the view and the value to set: 

@BindingAdapter("android:bufferType")
 public static void setBufferType(TextView view, TextView.BufferType bufferType) {
     view.setText(view.getText(), bufferType);
 }
In the above example, when android:bufferType is used on a TextView, the method setBufferType is called.

It is also possible to take previously set values, if the old values are listed first: 

@BindingAdapter("android:onLayoutChange")
 public static void setOnLayoutChangeListener(View view, View.OnLayoutChangeListener oldValue,
                                              View.OnLayoutChangeListener newValue) {
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
         if (oldValue != null) {
             view.removeOnLayoutChangeListener(oldValue);
         }
         if (newValue != null) {
             view.addOnLayoutChangeListener(newValue);
         }
     }
 }
When a binding adapter may also take multiple attributes, it will only be called when all attributes associated with the binding adapter have binding expressions associated with them. This is useful when there are unusual interactions between attributes. For example: 

@BindingAdapter({"android:onClick", "android:clickable"})
 public static void setOnClick(View view, View.OnClickListener clickListener,
                               boolean clickable) {
     view.setOnClickListener(clickListener);
     view.setClickable(clickable);
 }
The order of the parameters must match the order of the attributes in values in the BindingAdapter.

A binding adapter may optionally take a class extending DataBindingComponent as the first parameter as well. If it does, it will be passed the value passed in during binding, either directly in the inflate method or indirectly, using the value from getDefaultComponent().

If a binding adapter is an instance method, the generated DataBindingComponent will have a getter to retrieve an instance of the BindingAdapter's class to use to call the method.

Summary

Public methods

boolean requireAll()

Whether every attribute must be assigned a binding expression or if some can be absent.

String[] value()

Inherited methods

From interface java.lang.annotation.Annotation

Public methods

requireAll

boolean requireAll ()

Whether every attribute must be assigned a binding expression or if some can be absent. When this is false, the BindingAdapter will be called when at least one associated attribute has a binding expression. The attributes for which there was no binding expression (even a normal XML value) will cause the associated parameter receive the Java default value. Care must be taken to ensure that a default value is not confused with a valid XML value.

Returns
boolean whether or not every attribute must be assigned a binding expression. The default value is true.

value

String[] value ()

Returns
String[] The attributes associated with this binding adapter.