android - 无法创建 AndroidViewModel 的实例

Question

我正在尝试在应用程序中实现架构组件，但在创建 androidViewModel 实例时遇到了问题。请帮我解决这个问题。

我在这里尝试创建 LoginViewModel 类的实例，但出现以下错误

错误

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.addonitservices.uphaar, PID: 22975
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.addonitservices.uphaar/com.addonitservices.uphaar.login.LoginActivity}: java.lang.RuntimeException: Cannot create an instance of class com.addonitservices.uphaar.login.LoginViewModel
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
        at android.app.ActivityThread.-wrap11(Unknown Source:0)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
     Caused by: java.lang.RuntimeException: Cannot create an instance of class com.addonitservices.uphaar.login.LoginViewModel
        at android.arch.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:201)
        at android.arch.lifecycle.ViewModelProvider.get(ViewModelProvider.java:134)
        at android.arch.lifecycle.ViewModelProvider.get(ViewModelProvider.java:102)
        at com.addonitservices.uphaar.login.LoginActivity.initViewModel(LoginActivity.kt:27)
        at com.addonitservices.uphaar.login.LoginActivity.onCreate(LoginActivity.kt:22)
        at android.app.Activity.performCreate(Activity.java:6999)
        at android.app.Activity.performCreate(Activity.java:6990)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 
        at android.app.ActivityThread.-wrap11(Unknown Source:0) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:164) 
        at android.app.ActivityThread.main(ActivityThread.java:6494) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 
     Caused by: java.lang.NoSuchMethodException: <init> [class android.app.Application]
        at java.lang.Class.getConstructor0(Class.java:2320)
        at java.lang.Class.getConstructor(Class.java:1725)
        at android.arch.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:199)
        at android.arch.lifecycle.ViewModelProvider.get(ViewModelProvider.java:134) 
        at android.arch.lifecycle.ViewModelProvider.get(ViewModelProvider.java:102) 
        at com.addonitservices.uphaar.login.LoginActivity.initViewModel(LoginActivity.kt:27) 
        at com.addonitservices.uphaar.login.LoginActivity.onCreate(LoginActivity.kt:22) 
        at android.app.Activity.performCreate(Activity.java:6999) 
        at android.app.Activity.performCreate(Activity.java:6990) 
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214) 
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731) 
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 
        at android.app.ActivityThread.-wrap11(Unknown Source:0) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:164) 
        at android.app.ActivityThread.main(ActivityThread.java:6494) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 

Activity

import android.arch.lifecycle.ViewModelProvider
import android.arch.lifecycle.ViewModelProviders
import android.databinding.DataBindingUtil
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import com.addonitservices.uphaar.R
import com.addonitservices.uphaar.base.BaseActivity
import com.addonitservices.uphaar.databinding.ActivityLoginBinding
import com.mukesh.countrypicker.CountryPicker

class LoginActivity : BaseActivity() {

    private lateinit var binding: ActivityLoginBinding
    private lateinit var viewModel:LoginViewModel
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_login)
        binding.view = this
        initViewModel()

    }

    private fun initViewModel(){
        viewModel = ViewModelProviders.of(this).get(LoginViewModel::class.java)
        viewModel.initCountryPicker(getString(R.string.select_country))
        binding.viewModel =viewModel
    }


    fun onClick(view: View) {
        when (view.id) {

            R.id.btnLogin -> {}

            R.id.tvForgotPassword -> {}

            R.id.layoutCountryCode -> viewModel.showCountryPickerDialog(supportFragmentManager)

            R.id.tvSignUp -> {}
        }
    }



}

View 模型

import android.arch.lifecycle.MutableLiveData
    import android.support.v4.app.FragmentManager
    import com.addonitservices.uphaar.base.ApplicationClass
    import com.addonitservices.uphaar.base.BaseViewModel
    import com.mukesh.countrypicker.CountryPicker

    /**
     * Created by bms on 6/6/18 added in com.addonitservices.uphaar.login
     */
    class LoginViewModel(applicationClass: ApplicationClass) : BaseViewModel<LoginNavigator>(applicationClass) {


        val countryCode = MutableLiveData<String>()
        val flagImage = MutableLiveData<Int>()
        val mobileNumber = MutableLiveData<String>()
        val password = MutableLiveData<String>()
       private var countryPicker:CountryPicker? = null




         fun initCountryPicker(message:String){
            countryPicker = CountryPicker.newInstance(message)
            countryPicker?.setListener { name, code, dialCode, flag ->
                flagImage.value=flag
                countryCode.value =  dialCode
            }
        }

         fun showCountryPickerDialog(fragmentManager:FragmentManager){
            countryPicker?.show(fragmentManager,"COUNTRY_PICKER")
        }
}

基础 View 模型

open class BaseViewModel<N>(applicationClass: ApplicationClass) :AndroidViewModel(applicationClass) {


     var mNavigator: N? = null

}

Answer 1

LoginViewModel(applicationClass: ApplicationClass)

应该是

LoginViewModel(application: android.app.Application)