Android Inventory App添加搜索栏崩溃：SearchResultViewModel未设初始化器

你的崩溃原因很明确：AppViewModelProvider 中没有为 SearchResultViewModel 添加初始化器，系统无法创建该ViewModel的实例，因此抛出了No initializer set for given class异常。

修复步骤 #

修改 AppViewModelProvider 类，在 Factory 中补充 SearchResultViewModel 的初始化代码：

package com.example.inventory.ui

import android.app.Application
import androidx.lifecycle.ViewModelProvider.AndroidViewModelFactory
import androidx.lifecycle.createSavedStateHandle
import androidx.lifecycle.viewmodel.CreationExtras
import androidx.lifecycle.viewmodel.initializer
import androidx.lifecycle.viewmodel.viewModelFactory
import com.example.inventory.InventoryApplication
import com.example.inventory.ui.home.HomeViewModel
import com.example.inventory.ui.item.ItemDetailsViewModel
import com.example.inventory.ui.item.ItemEditViewModel
import com.example.inventory.ui.item.ItemEntryViewModel
import com.example.inventory.ui.searchResultScreen.SearchResultViewModel

/**
 * Provides Factory to create instance of ViewModel for the entire Inventory app
 */
object AppViewModelProvider {
    val Factory = viewModelFactory {
        // Initializer for ItemEditViewModel
        initializer {
            ItemEditViewModel(
                this.createSavedStateHandle(),
                inventoryApplication().container.itemsRepository
            )
        }
        // Initializer for ItemEntryViewModel
        initializer {
            ItemEntryViewModel(inventoryApplication().container.itemsRepository)
        }

        // Initializer for ItemDetailsViewModel
        initializer {
            ItemDetailsViewModel(
                this.createSavedStateHandle(),
                inventoryApplication().container.itemsRepository
            )
        }

        // Initializer for HomeViewModel
        initializer {
            HomeViewModel(inventoryApplication().container.itemsRepository)
        }

        // 添加SearchResultViewModel的初始化器
        initializer {
            SearchResultViewModel(
                this.createSavedStateHandle(),
                inventoryApplication().container.itemsRepository
            )
        }
    }
}

/**
 * Extension function to queries for [Application] object and returns an instance of
 * [InventoryApplication].
 */
fun CreationExtras.inventoryApplication(): InventoryApplication =
    (this[AndroidViewModelFactory.APPLICATION_KEY] as InventoryApplication)

额外验证点 #

确认导航到SearchResultScreen时，已正确将searchQuery参数传入SavedStateHandle（比如在导航图中定义了对应参数，且跳转时传递了有效值），否则checkNotNull(savedStateHandle[SearchResultDestination.searchQueryArg])会触发空指针异常。

内容的提问来源于stack exchange，提问作者Ajew