應用程式不斷崩潰，Logcat狀態“lateinit屬性todoAdapter尚未初始化”

這是一個簡單的待辦事項串列應用程式的主要活動，如果您想查看更多代碼，請告訴我

當 private lateinit var todoAdapter: TodoAdapter 被洗掉時，應用不再崩潰，但應用將不再在回收站視圖上顯示待辦事項

"package com.example.todoit

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.text.TextUtils
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.todoit.data.Todo
import com.example.todoit.data.TodoViewModel
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity() {
    private lateinit var todoAdapter: TodoAdapter
    private lateinit var todoViewModel: TodoViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        rvTodoItems.layoutManager = LinearLayoutManager(this)
        rvTodoItems.adapter = todoAdapter

        btnAddTodo.setOnClickListener {

            val todoTitle = etTodoTitle.text.toString()
            if (todoTitle.isNotEmpty()) {
                val todo = Todo(0,todoTitle,false)
                etTodoTitle.text.clear()
                insertDataToDataBase()
                todoAdapter.addTodo(todo)
            }
        }
        btnDeleteTodo.setOnClickListener {
            todoAdapter.deleteDoneTodos()
        }
    }

    private fun insertDataToDataBase() {
        val todoTitle = etTodoTitle.text.toString()

        if(inputCheck(todoTitle)) {

            val todo = Todo(0, todoTitle, isChecked = false)
            //Add data to database
            todoViewModel.addTodoToDataBase(todo)
            Toast.makeText(this, "Successfully Added", Toast.LENGTH_LONG).show()
        }else{
            Toast.makeText(this, "Please fill out all fields", Toast.LENGTH_LONG).show()
            }
        }




    private fun inputCheck(todoTitle:String):Boolean {
        return !(TextUtils.isEmpty(todoTitle))
    }
}

uj5u.com熱心網友回復：

你忘了初始化你的 todoAdapter，你需要在呼叫它之前初始化 todoAdapter。

class MainActivity : AppCompatActivity() {
    private lateinit var todoAdapter: TodoAdapter
    private lateinit var todoViewModel: TodoViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        todoAdapter = TodoAdapter() // if TodoAdapter requires parameters you need to pass them
        rvTodoItems.layoutManager = LinearLayoutManager(this)
        rvTodoItems.adapter = todoAdapter

        btnAddTodo.setOnClickListener {

            val todoTitle = etTodoTitle.text.toString()
            if (todoTitle.isNotEmpty()) {
                val todo = Todo(0,todoTitle,false)
                etTodoTitle.text.clear()
                insertDataToDataBase()
                todoAdapter.addTodo(todo)
            }
        }
        btnDeleteTodo.setOnClickListener {
            todoAdapter.deleteDoneTodos()
        }
    }

    private fun insertDataToDataBase() {
        val todoTitle = etTodoTitle.text.toString()

        if(inputCheck(todoTitle)) {

            val todo = Todo(0, todoTitle, isChecked = false)
            //Add data to database
            todoViewModel.addTodoToDataBase(todo)
            Toast.makeText(this, "Successfully Added", Toast.LENGTH_LONG).show()
        }else{
            Toast.makeText(this, "Please fill out all fields", Toast.LENGTH_LONG).show()
            }
        }




    private fun inputCheck(todoTitle:String):Boolean {
        return !(TextUtils.isEmpty(todoTitle))
    }
}

uj5u.com熱心網友回復：

該錯誤清除了您的 todoAdapter 未初始化，您必須在使用之前進行初始化，如下所示：

todoAdapter=TodoAdapter(yourprams) 


        rvTodoItems.layoutManager = LinearLayoutManager(this)
        rvTodoItems.adapter = todoAdapter

        btnAddTodo.setOnClickListener {

            val todoTitle = etTodoTitle.text.toString()
            if (todoTitle.isNotEmpty()) {
                val todo = Todo(0,todoTitle,false)
                etTodoTitle.text.clear()
                insertDataToDataBase()
                todoAdapter.addTodo(todo)
            }
        }
        btnDeleteTodo.setOnClickListener {
            todoAdapter.deleteDoneTodos()
        }
    }

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