android - lateinit 属性性别尚未初始化

Question

使用数据绑定(bind)、ViewModel、LiveData ( MVVM )。
在我的布局中有一个表单可以添加员工详细信息。
布局:

<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
<data>
    <variable
        name="viewModelAddEmployee"
        type="com.app.roomemployeedemo.viewmodel.AddEmployeeViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
    android:id="@+id/edt_lastname"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".activity.AddEmployeeActivity">
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true">
        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">
            <EditText
                android:text="@{viewModelAddEmployee.firstname}"
                android:id="@+id/edt_firstname"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="40dp"
                android:ems="10"
                android:hint="Jaimin"
                android:inputType="textPersonName"
                android:maxLength="30"
                android:maxLines="1"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />
            <EditText
                android:text="@{viewModelAddEmployee.lastname}"
                android:id="@+id/tv_lastname"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:ems="10"
                android:hint="Modi"
                android:inputType="textPersonName"
                android:maxLength="30"
                android:maxLines="1"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/edt_firstname" />
            <EditText
                android:text="@{viewModelAddEmployee.age}"
                android:id="@+id/edt_age"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:ems="10"
                android:hint="25"
                android:inputType="textPersonName"
                android:maxLength="3"
                android:maxLines="1"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/tv_lastname" />
            <EditText
                android:text="@{viewModelAddEmployee.gender}"
                android:id="@+id/edt_gender"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:ems="10"
                android:hint="Gender (M/F, m/f)"
                android:inputType="textPersonName"
                android:maxLength="1"
                android:maxLines="1"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/edt_age" />
            <EditText
                android:text="@{viewModelAddEmployee.salary}"
                android:id="@+id/edt_salary"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:ems="10"
                android:hint="Salary (50000)"
                android:inputType="textPersonName"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/edt_gender" />
            <Button
                android:onClick="@{(v) -> viewModelAddEmployee.onAddEmployeeClick(v)}"
                android:id="@+id/button"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginStart="40dp"
                android:layout_marginTop="40dp"
                android:layout_marginEnd="40dp"
                android:text="ADD NOW"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintHorizontal_bias="0.5"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/edt_salary" />
        </androidx.constraintlayout.widget.ConstraintLayout>
    </ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>

下面是相同的 ViewModel 类:

 class AddEmployeeViewModel(mContext: Context) : ViewModel(){
    var mContext=mContext
    lateinit var firstname:MutableLiveData<String>
    lateinit var lastname:MutableLiveData<String>
    lateinit var age:MutableLiveData<Int>
    lateinit var gender:MutableLiveData<Char>
    lateinit var salary:MutableLiveData<Int>
    lateinit var repositoryEmployee:EmployeeRepository
    init{
        repositoryEmployee= EmployeeRepository(mContext)
    }
    fun onAddEmployeeClick(view: View)
    {
        repositoryEmployee.onAddEmployeeClick(mContext,firstname,lastname,age,gender,salary)
    }
}

Activity 类中初始化的 Viewmodel 和绑定(bind)实用程序如下:

class AddEmployeeActivity : AppCompatActivity() {
lateinit var viewModelAddEmployee: AddEmployeeViewModel
lateinit var binding: ActivityAddEmployeeBinding
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    viewModelAddEmployee = ViewModelProvider(this,AddEmployeeFactory(this@AddEmployeeActivity)).get(AddEmployeeViewModel::class.java)
    binding = DataBindingUtil.setContentView(
        this@AddEmployeeActivity,
        R.layout.activity_add_employee
    )
    binding?.setLifecycleOwner(this)
    binding?.viewModelAddEmployee = viewModelAddEmployee
}

}
但是，出现以下错误:

Caused by: kotlin.UninitializedPropertyAccessException: lateinit property gender has not been initialized
            at com.app.roomemployeedemo.viewmodel.AddEmployeeViewModel.getGender(AddEmployeeViewModel.kt:16)

可能是什么问题？尤其是 Char 类型的性别!

Answer 1

在 kotlin 中，您必须初始化 lateinit 属性。将以下行添加到 oncreate -

 gender = MutableLiveData<Char>()