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@Target(value={METHOD,ANNOTATION_TYPE}) public @interface 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 BindingAdapter
s:
@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 BindingAdapter
s, InverseBindingAdapter methods may also take
DataBindingComponent
as the first parameter and may be an instance method with the
instance retrieved from the DataBindingComponent
.
DataBindingUtil#setDefaultComponent(DataBindingComponent)
,
InverseBindingMethod
Required Element Summary | |
---|---|
java.lang.String |
attribute
The attribute that the value is to be retrieved for. |
Optional Element Summary | |
---|---|
java.lang.String |
event
The event used to trigger changes. |
Element Detail |
---|
public abstract java.lang.String attribute
public abstract java.lang.String event
BindingAdapter
s for the
data binding system to set the event listener when two-way binding is used.
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