android - 双向数据绑定(bind)错误 : cannot resolve a setter for boolean property

Question

我正在尝试在复选框上使用双向数据绑定(bind):

<layout xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">
    <data>
        <import type="android.view.View"/>
        <variable
            name="viewModel"
      type="com.epsilon.startbodyweight.selectorActivity.SelectorViewModel"/>
        <variable
            name="index"
            type="int" />
    </data>

    <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <CheckBox
            android:id="@+id/cb_active_exer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="8dp"
            android:checked="@={viewModel.exerciseList[index].isActive}" />

这给了我以下错误:

数据绑定(bind)错误消息:无法反转表达式 viewModelExerciseListIndex.isActive():双向绑定(bind)无法解析 bool 属性“isActive”的 setter

我有以下类(class):

@Entity
class ExerciseEntity {
    var exerciseName: String = ""
    @PrimaryKey
    var exerciseNum: Int = 0
    var progressionName: String = ""
    var progressionNumber: Int = 0
    var set1Reps: Int = 0
    var set2Reps: Int = 0
    var set3Reps: Int = 0
    var setTime: Int = 0
    var isTimedExercise: Boolean = false
    var numAttempts: Int = 0
    var isActive: Boolean = true

    // Do not store the following items in our DB
    @Ignore var allProgressions: ArrayList<String> = ArrayList()
    @Ignore var nextSet1Reps: Int = 0
    @Ignore var nextSet2Reps: Int = 0
    @Ignore var nextSet3Reps: Int = 0
    @Ignore var nextSetTime: Int = 0
    @Ignore var nextNumAttempts: Int = 0
    @Ignore var nextProgressionName: String = ""
    @Ignore var nextProgressionNumber: Int = 0
    @Ignore var isModified: Boolean = false
    @Ignore var exerMessage: String = ""
    @Ignore var isSet1Complete: Boolean = false
    @Ignore var isSet2Complete: Boolean = false
    @Ignore var isSet3Complete: Boolean = false
    @Ignore var isSetTimeComplete: Boolean = false
}

根据要求，这是 SelectorViewModel:

选择器 View 模型:

class SelectorViewModel : ViewModel() {
    private val mExerciseList = MutableLiveData<ArrayList<ExerciseEntity>>()
    val exerciseList : LiveData<ArrayList<ExerciseEntity>>
        get() = mExerciseList

    init {
        mExerciseList.value = ArrayList()
    }

    fun populateExerciseListFromDB(myDBExercises: List<ExerciseEntity>) {
        // .... Load our exer list from DB ... //


        mExerciseList.value?.addAll(myDBExercises)
        // Use the "setValue" method to notify observers of change
        mExerciseList.value = mExerciseList.value
    }

    private fun updateRepsInExercise(exercise: ExerciseEntity, reps1: Int, reps2: Int, reps3: Int) {
        exercise.set1Reps = reps1
        exercise.set2Reps = reps2
        exercise.set3Reps = reps3

        mExerciseList.value = mExerciseList.value
    }

    fun incrementSet(exercise: ExerciseEntity, smallIncrement: Boolean) {
            // ... Compute the new reps ... //
            updateRepsInExercise(exercise, numReps1, numReps2, numReps3)
    }
}

请注意:这不是 this question 的重复项这是指 Android Studio 2.2 中的一个错误并且正在使用 Java。我在 Kotlin 中使用 3.2 版。

我试图为函数 isActive 手动创建一个 setter，但它提示说已经为 bool 属性定义了一个 setter。

Answer 1

在编写绑定(bind)表达式时仔细检查自动完成中可用的属性。以 is 开头的 Kotlin Boolean 出现在没有它的绑定(bind)表达式语言中。

例如，考虑一个具有名为 isActive 的属性的 Kotlin 数据类。

data class Exercise(var isActive: Boolean)

在绑定(bind)表达式中，此属性将显示为active，而不是isActive。

<CheckBox
  android:checked="@={viewModel.exercise.active}" />