当我尝试运行我的应用程序时，错误显示您已经初始化了适配器，而我已经初始化了适配器。它表明reyclerview也必须是init，但是由于我已经这样做了，所以我没有解决方案，请提供帮助。
代码在下面
package com.example.itemgetset
import android.annotation.SuppressLint
import android.app.Activity
import android.content.Intent
import android.os.Bundle
import android.os.Handler
import android.os.Message
import android.view.Menu
import android.view.MenuItem
import android.view.View
import android.widget.Button
import android.widget.LinearLayout
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
lateinit var activity: Activity
val userList = ArrayList<ProductInfoGetSet>()
lateinit var btnProductAdd: Button
lateinit var llEmptyView: LinearLayout
lateinit var llMain: LinearLayout
lateinit var recyclerView: RecyclerView
lateinit var llFab: LinearLayout
lateinit var linearLayoutManager: LinearLayoutManager
lateinit var gridLayoutManager: GridLayoutManager
lateinit var adapter: CustomAdapter
companion object {
var handler: Handler = Handler()
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
linearLayoutManager = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
recyclerView.layoutManager = linearLayoutManager
gridLayoutManager = GridLayoutManager(this, 2)
recyclerView.layoutManager = gridLayoutManager
activity = this
initView()
onClicks()
setUpData()
if (this::adapter.isInitialized)
handler = @SuppressLint("HandlerLeak")
object : Handler() {
override fun handleMessage(msg: Message) {
if (msg.what == 111) {
var temp = Temp()
temp = msg.obj as Temp
if (temp.id == "") {
userList.add(
ProductInfoGetSet(
(userList.size + 1).toString(),
temp.name,
temp.quantity,
temp.price,
)
)
adapter = CustomAdapter(activity, userList)
recyclerView.adapter = adapter
} else {
for (i in userList.indices) {
if (userList[i].id == temp.id) {
userList[i].id = temp.id
userList[i].name = temp.name
userList[i].quantity = temp.quantity
userList[i].price = temp.price
}
}
adapter.notifyDataSetChanged()
}
}
if (userList.size > 0) {
llEmptyView.visibility = View.GONE
llMain.visibility = View.VISIBLE
} else {
llEmptyView.visibility = View.VISIBLE
llMain.visibility = View.GONE
}
}
}
}
private fun initView() {
btnProductAdd = findViewById(R.id.btn_product_add)
llFab = findViewById(R.id.ll_fab)
llEmptyView = findViewById(R.id.llEmptyView)
llMain = findViewById(R.id.llMain)
recyclerView = findViewById(R.id.recycler_view)
recyclerView.layoutManager = LinearLayoutManager(this)
}
private fun onClicks() {
btnProductAdd.setOnClickListener {
val intent = Intent(this@MainActivity, AddDetails::class.java)
intent.putExtra("isFor", "Add")
startActivity(intent)
}
llFab.setOnClickListener {
val intent = Intent(this@MainActivity, AddDetails::class.java)
intent.putExtra("isFor", "Add")
startActivity(intent)
}
}
private fun setUpData() {
if (userList.size > 0) {
llEmptyView.visibility = View.GONE
llMain.visibility = View.VISIBLE
} else {
llEmptyView.visibility = View.VISIBLE
llMain.visibility = View.GONE
}
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
menuInflater.inflate(R.menu.menu_main, menu)
return true
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
if (item.itemId == R.id.menu_view) {
changeLayoutManager()
return true
}
return super.onOptionsItemSelected(item)
}
private fun changeLayoutManager() {
if (recycler_view.layoutManager == linearLayoutManager) {
recycler_view.layoutManager = gridLayoutManager
if (userList.size != 1) return
} else {
recycler_view.layoutManager = linearLayoutManager
}
}
}
然后显示的错误在下面
Process: com.example.itemgetset, PID: 17453
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.itemgetset/com.example.itemgetset.MainActivity}: kotlin.UninitializedPropertyAccessException: lateinit property recyclerView has not been initialized
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3385)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3524)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2131)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7707)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
Caused by: kotlin.UninitializedPropertyAccessException: lateinit property recyclerView has not been initialized
at com.example.itemgetset.MainActivity.onCreate(MainActivity.kt:43)
at android.app.Activity.performCreate(Activity.java:7825)
at android.app.Activity.performCreate(Activity.java:7814)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1325)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3360)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3524)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2131)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7707)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
第43行是recyclerView.layoutManager = gridLayoutManager 这个，我已经初始化了。请提供帮助。在此先感谢
答案 0 :(得分：1)
您没有初始化“ recyclerView”本身。您可能应该将其作为recyclerView = findViewById(R.id.recyclerView)来执行，或者从类的顶部删除lateinit var recyclerView。该变量可能与直接来自您的布局的视图本身冲突。
答案 1 :(得分：0)
这里没有什么要注意的
尝试一下：
class MainActivity : AppCompatActivity() {
lateinit var activity: Activity
val userList = ArrayList<ProductInfoGetSet>()
lateinit var btnProductAdd: Button
lateinit var llEmptyView: LinearLayout
lateinit var llMain: LinearLayout
lateinit var recyclerView: RecyclerView
lateinit var llFab: LinearLayout
lateinit var linearLayoutManager: LinearLayoutManager
lateinit var gridLayoutManager: GridLayoutManager
lateinit var adapter: CustomAdapter
companion object {
var handler: Handler = Handler()
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
initView()
linearLayoutManager = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
recyclerView.layoutManager = linearLayoutManager
gridLayoutManager = GridLayoutManager(this, 2)
recyclerView.layoutManager = gridLayoutManager
activity = this
onClicks()
setUpData()
if (this::adapter.isInitialized)
handler = @SuppressLint("HandlerLeak")
object : Handler() {
override fun handleMessage(msg: Message) {
if (msg.what == 111) {
var temp = Temp()
temp = msg.obj as Temp
if (temp.id == "") {
userList.add(
ProductInfoGetSet(
(userList.size + 1).toString(),
temp.name,
temp.quantity,
temp.price,
)
)
adapter = CustomAdapter(activity, userList)
recyclerView.adapter = adapter
} else {
for (i in userList.indices) {
if (userList[i].id == temp.id) {
userList[i].id = temp.id
userList[i].name = temp.name
userList[i].quantity = temp.quantity
userList[i].price = temp.price
}
}
adapter.notifyDataSetChanged()
}
}
if (userList.size > 0) {
llEmptyView.visibility = View.GONE
llMain.visibility = View.VISIBLE
} else {
llEmptyView.visibility = View.VISIBLE
llMain.visibility = View.GONE
}
}
}
}
.........
....
}