相关疑难解决方法(0)

即使我多次更新 LiveData，我的 BindingAdapter 也只运行一次。

public class ButtonViewBindingAdapter
{
    @BindingAdapter("hideIfZero")
    public static void setHideIfZero(View view, MutableLiveData<Integer> currentPosition)
    {
        view.setVisibility(currentPosition.getValue() == 0 ? View.GONE : View.VISIBLE);
    }
}

<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>
        <variable
            name="viewModel"
            type="com.package.PermissionsViewModel"/>

        <variable
            name="clickHandler"
            type="com.package.PermissionsActivity.ClickHandler"/>
    </data>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <Button
            android:id="@+id/buttonNext"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:layout_alignParentBottom="true"
            android:background="@null"
            android:onClick="@{() -> clickHandler.nextSlide()}"
            android:text="@string/intro_next"
            android:textColor="@android:color/white"
            />

        <Button
            android:id="@+id/buttonBack"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentBottom="true"
            android:background="@null"
            android:onClick="@{() -> clickHandler.previousSlide()}"
            android:text="@string/intro_back"
            android:textColor="@android:color/white"
            app:hideIfZero="@{viewModel.currentSlidePosition}"/>

    </RelativeLayout>
</layout>

public class PermissionsViewModel extends ViewModel
{
    private MutableLiveData<Integer> currentSlidePosition = new MutableLiveData<>(); …