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InverseBindingAdapter

public abstract @interface InverseBindingAdapter
implements Annotation

android.databinding.InverseBindingAdapter


InverseBindingAdapter is associated with a method used to retrieve the value for a View when setting values gathered from the View. This is similar to BindingAdapters:

 @InverseBindingAdapter(attribute = "android:text", event = "android:textAttrChanged")
 public static String captureTextValue(TextView view, CharSequence originalValue) {
     CharSequence newValue = view.getText();
     CharSequence oldValue = value.get();
     if (oldValue == null) {
         value.set(newValue);
     } else if (!contentEquals(newValue, oldValue)) {
         value.set(newValue);
     }
 }
 

The default value for event is the attribute name suffixed with "AttrChanged". In the above example, the default value would have been android:textAttrChanged even if it wasn't provided.

The event attribute is used to notify the data binding system that the value has changed. The developer will typically create a BindingAdapter to assign the event. For example:

 @BindingAdapter(value = {"android:beforeTextChanged", "android:onTextChanged",
                          "android:afterTextChanged", "android:textAttrChanged"},
                          requireAll = false)
 public static void setTextWatcher(TextView view, final BeforeTextChanged before,
                                   final OnTextChanged on, final AfterTextChanged after,
                                   final InverseBindingListener textAttrChanged) {
     TextWatcher newValue = new TextWatcher() {
         ...
         @Override
         public void onTextChanged(CharSequence s, int start, int before, int count) {
             if (on != null) {
                 on.onTextChanged(s, start, before, count);
             }
             if (textAttrChanged != null) {
                 textAttrChanged.onChange();
             }
         }
     }
     TextWatcher oldValue = ListenerUtil.trackListener(view, newValue, R.id.textWatcher);
     if (oldValue != null) {
         view.removeTextChangedListener(oldValue);
     }
     view.addTextChangedListener(newValue);
 }
 

Like BindingAdapters, InverseBindingAdapter methods may also take DataBindingComponent as the first parameter and may be an instance method with the instance retrieved from the DataBindingComponent.

See also:

Summary

Public methods

String attribute()

The attribute that the value is to be retrieved for.

String event()

The event used to trigger changes.

Inherited methods

From interface java.lang.annotation.Annotation

Public methods

attribute

String attribute ()

The attribute that the value is to be retrieved for.

Returns
String

event

String event ()

The event used to trigger changes. This is used in BindingAdapters for the data binding system to set the event listener when two-way binding is used.

Returns
String

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