java.lang.RuntimeException 中的错误：无法启动 activity ComponentInfo{}：java.lang.NullPointerException
error in java.lang.RuntimeException: Unable to start activity ComponentInfo{}: java.lang.NullPointerException
我在 android studio 中出现以下错误，问题是在添加产品时，因为如果没有产品，它会打开购物袋，但在添加一个并想重新输入时，它关闭，当您想进入购物袋购买时，应用程序关闭。
我真的很想得到你的帮助，因为我不是这个应用程序的专家，我也没有时间交付它，我将附上执行应用程序时出错的图片和视频
购物袋适配器
class ShoppingBagAdapter(val context: Activity, val products: ArrayList): RecyclerView.Adapter() {
val sharedPref = SharedPref(context)
val TAG = "ShoppingBag"
init {
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ShoppingBagViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.cardview_shopping_bag, parent, false)
return ShoppingBagViewHolder(view)
}
override fun getItemCount(): Int {
return products.size
}
override fun onBindViewHolder(holder: ShoppingBagViewHolder, position: Int) {
val product = products[position] // CADA UNA DE LAS CATEGORIAS
holder.textViewName.text = product.name
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.price * product.quantity!!}"
Glide.with(context).load(product.image1).into(holder.imageViewProduct)
holder.imageViewAdd.setOnClickListener { addItem(product, holder) }
holder.imageViewRemove.setOnClickListener { removeItem(product, holder) }
holder.imageViewDelete.setOnClickListener { deleteItem(position) }
// holder.itemView.setOnClickListener { goToDetail(产品) }
}
private fun getTotal(): Double {
var total = 0.0
for (p in products) {
total = total + (p.quantity!! * p.price)
}
return total
}
private fun getIndexOf(idProduct: String): Int {
var pos = 0
for (p in products) {
if (p.id == idProduct) {
return pos
}
pos++
}
return -1
}
private fun deleteItem(position: Int) {
products.removeAt(position)
notifyItemRemoved(position)
notifyItemRangeRemoved(position, products.size)
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
private fun addItem(product: Product, holder: ShoppingBagViewHolder) {
val index = getIndexOf(product.id!!)
product.quantity = product.quantity!! + 1
products[index].quantity = product.quantity
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.quantity!! * product.price}$"
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
private fun removeItem(product: Product, holder: ShoppingBagViewHolder) {
if (product.quantity!! > 1) {
val index = getIndexOf(product.id!!)
product.quantity = product.quantity!! - 1
products[index].quantity = product.quantity
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.quantity!! * product.price}$"
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
}
private fun goToDetail(product: Product) {
val i = Intent(context, ClientProductsDetailActivity::class.java)
i.putExtra("product", product.toJson())
context.startActivity(i)
}
class ShoppingBagViewHolder(view: View): RecyclerView.ViewHolder(view) {
val textViewName: TextView
val textViewPrice: TextView
val textViewCounter: TextView
val imageViewProduct: ImageView
val imageViewAdd: ImageView
val imageViewRemove: ImageView
val imageViewDelete: ImageView
init {
textViewName = view.findViewById(R.id.textview_name)
textViewPrice = view.findViewById(R.id.textview_price)
textViewCounter = view.findViewById(R.id.textview_counter)
imageViewProduct = view.findViewById(R.id.imageview_product)
imageViewAdd = view.findViewById(R.id.imageview_add)
imageViewRemove = view.findViewById(R.id.imageview_remove)
imageViewDelete = view.findViewById(R.id.imageview_delete)
}
}
ClientShoppingBagActivity
class ClientShoppingBagActivity : AppCompatActivity() {
var recyclerViewShoppingBag: RecyclerView? = null
var textViewTotal: TextView? = null
var buttomNext: Button? = null
var toolbar: Toolbar? = null
var adapter: ShoppingBagAdapter? = null
var sharedPref: SharedPref? = null
var gson = Gson()
var selectedProducts = ArrayList<Product>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_client_shopping_bag)
sharedPref = SharedPref(this)
recyclerViewShoppingBag = findViewById(R.id.recyclerview_shopping_bag)
textViewTotal = findViewById(R.id.textview_total)
buttomNext = findViewById(R.id.btn_next)
toolbar = findViewById(R.id.toolbar)
toolbar?.setTitleTextColor(ContextCompat.getColor(this, R.color.white))
toolbar?.title = "Tu orden"
setSupportActionBar(toolbar)
supportActionBar?.setDisplayHomeAsUpEnabled(true)
recyclerViewShoppingBag?.layoutManager = LinearLayoutManager(this)
getProductsFromSharedPref()
buttomNext?.setOnClickListener{goToAddressList() }
}
private fun goToAddressList(){
val i = Intent(this, ClientAddressListActivity::class.java)
startActivity(i)
}
fun setTotal(total: Double){
textViewTotal?.text = "${total}$"
}
private fun getProductsFromSharedPref() {
if (!sharedPref?.getData("order").isNullOrBlank()) { // EXISTE UNA ORDEN EN SHARED PREF
val type = object : TypeToken<ArrayList<Product>>() {}.type
selectedProducts = gson.fromJson(sharedPref?.getData("order"), type)
adapter = ShoppingBagAdapter(this, selectedProducts)
recyclerViewShoppingBag?.adapter = adapter
}
}
link 视频 其中应用是运行 所以你可以看到错误在哪里 https://youtu.be/iUNCo5aCLLY
这里有一个更明确的视频关于问题的问题，我真的希望你可以帮助我https://youtu.be/T262TUQxRVw
现在我将继续附上图片，这样你就可以看到错误的完整描述，尽管我也可以在下面看到它们
image 1 where is the complete error
in this image I specify the error line
in this image I specify the other line of the error
in this image I specify the other line of the error
in this image I specify the other line of the error
完整的错误描述
2022-05-16 16:28:46.508 6163-6163/com.blader.domicilios E/AndroidRuntime：致命异常：main
进程：com.blader.domicilios，PID：6163
java.lang.RuntimeException: 无法启动 activity ComponentInfo{com.blader.domicilios/com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity}: java.lang.NullPointerException
在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
在 android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
在 android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
在 android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
在 android.os.Handler.dispatchMessage(Handler.java:106)
在 android.os.Looper.loop(Looper.java:223)
在 android.app.ActivityThread.main(ActivityThread.java:7656)
在 java.lang.reflect.Method.invoke（本机方法）
在 com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
原因：java.lang.NullPointerException
在 com.blader.domicilios.adapters.ShoppingBagAdapter.getTotal(ShoppingBagAdapter.kt:57)
在 com.blader.domicilios.adapters.ShoppingBagAdapter.(ShoppingBagAdapter.kt:25)
在 com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity.getProductsFromSharedPref(ClientShoppingBagActivity.kt:73)
在 com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity.onCreate(ClientShoppingBagActivity.kt:52)
在 android.app.Activity.performCreate(Activity.java:8000)
在 android.app.Activity.performCreate(Activity.java:7984)
在 android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
在 android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
在 android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
在 android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
在 android.os.Handler.dispatchMessage(Handler.java:106)
在 android.os.Looper.loop(Looper.java:223)
在 android.app.ActivityThread.main(ActivityThread.java:7656)
在 java.lang.reflect.Method.invoke（本机方法）
我真的很担心你不能帮我能按时交作业，我的时间真的很少**
您还没有发布完整的堆栈跟踪，所以我只是猜测，但我认为是这一行：
total = total + (p.quantity!! * p.price)
quantity 是可以为 null 的类型，您应该 null-check 那些以确保它们 not null 在你做任何事情之前他们。 !! 始终是一个不好的迹象，它的意思是“我保证这永远不会为空”，我的猜测是 quantity is null 这就是它崩溃的原因。 （这就是为什么你应该始终处理空值并且永远不要使用 !! 除非你完全知道你在做什么以及为什么需要它）
你或许可以用这个来解决它：
private fun getTotal(): Double {
var total = 0.0
for (p in products) {
if (p.quantity != null) total += p.quantity * p.price
}
return total
}
或者如果您愿意：
private fun getTotal(): Double =
products.sumByDouble { p -> (p.quantity ?: 0) * p.price }
我不知道你的应用程序是否明显存在任何其他问题，但希望这应该能阻止你获得特定的 NullPointerException
这是现在的错误所在，当我再次尝试添加产品时应用程序关闭，我会再次附上截图
here I select where the error marks, so that you can see which is the line that sends me the error, once thanks for helping me
enter image description here
再次向我发送错误的代码****
import android.app.Activity
import android.content.Intent
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.blader.domicilios.R
import com.blader.domicilios.activities.client.products.detail.ClientProductsDetailActivity
import com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity
import com.blader.domicilios.models.Product
import com.blader.domicilios.utils.SharedPref
import com.bumptech.glide.Glide
class ShoppingBagAdapter(val context: Activity, val products: ArrayList<Product>): RecyclerView.Adapter<ShoppingBagAdapter.ShoppingBagViewHolder>() {
val sharedPref = SharedPref(context)
val TAG = "ShoppingBag"
init {
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ShoppingBagViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.cardview_shopping_bag, parent, false)
return ShoppingBagViewHolder(view)
}
override fun getItemCount(): Int {
return products.size
}
override fun onBindViewHolder(holder: ShoppingBagViewHolder, position: Int) {
val product = products[position] // CADA UNA DE LAS CATEGORIAS
holder.textViewName.text = product.name
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.price * product.quantity!!}"
Glide.with(context).load(product.image1).into(holder.imageViewProduct)
holder.imageViewAdd.setOnClickListener { addItem(product, holder) }
holder.imageViewRemove.setOnClickListener { removeItem(product, holder) }
holder.imageViewDelete.setOnClickListener { deleteItem(position) }
// holder.itemView.setOnClickListener { goToDetail(product) }
}
private fun getTotal(): Double =
products.sumByDouble { p -> (p.quantity ?: 0) * p.price }
private fun getIndexOf(idProduct: String): Int {
var pos = 0
for (p in products) {
if (p.id == idProduct) {
return pos
}
pos++
}
return -1
}
private fun deleteItem(position: Int) {
products.removeAt(position)
notifyItemRemoved(position)
notifyItemRangeRemoved(position, products.size)
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
private fun addItem(product: Product, holder: ShoppingBagViewHolder) {
val index = getIndexOf(product.id!!)
product.quantity = product.quantity!! + 1
products[index].quantity = product.quantity
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.quantity!! * product.price}$"
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
private fun removeItem(product: Product, holder: ShoppingBagViewHolder) {
if (product.quantity!! > 1) {
val index = getIndexOf(product.id!!)
product.quantity = product.quantity!! - 1
products[index].quantity = product.quantity
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.quantity!! * product.price}$"
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
}
private fun goToDetail(product: Product) {
val i = Intent(context, ClientProductsDetailActivity::class.java)
i.putExtra("product", product.toJson())
context.startActivity(i)
}
class ShoppingBagViewHolder(view: View): RecyclerView.ViewHolder(view) {
val textViewName: TextView
val textViewPrice: TextView
val textViewCounter: TextView
val imageViewProduct: ImageView
val imageViewAdd: ImageView
val imageViewRemove: ImageView
val imageViewDelete: ImageView
init {
textViewName = view.findViewById(R.id.textview_name)
textViewPrice = view.findViewById(R.id.textview_price)
textViewCounter = view.findViewById(R.id.textview_counter)
imageViewProduct = view.findViewById(R.id.imageview_product)
imageViewAdd = view.findViewById(R.id.imageview_add)
imageViewRemove = view.findViewById(R.id.imageview_remove)
imageViewDelete = view.findViewById(R.id.imageview_delete)
}
}
我在 android studio 中出现以下错误，问题是在添加产品时，因为如果没有产品，它会打开购物袋，但在添加一个并想重新输入时，它关闭，当您想进入购物袋购买时，应用程序关闭。
我真的很想得到你的帮助，因为我不是这个应用程序的专家，我也没有时间交付它，我将附上执行应用程序时出错的图片和视频
购物袋适配器
class ShoppingBagAdapter(val context: Activity, val products: ArrayList): RecyclerView.Adapter
val sharedPref = SharedPref(context)
val TAG = "ShoppingBag"
init {
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ShoppingBagViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.cardview_shopping_bag, parent, false)
return ShoppingBagViewHolder(view)
}
override fun getItemCount(): Int {
return products.size
}
override fun onBindViewHolder(holder: ShoppingBagViewHolder, position: Int) {
val product = products[position] // CADA UNA DE LAS CATEGORIAS
holder.textViewName.text = product.name
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.price * product.quantity!!}"
Glide.with(context).load(product.image1).into(holder.imageViewProduct)
holder.imageViewAdd.setOnClickListener { addItem(product, holder) }
holder.imageViewRemove.setOnClickListener { removeItem(product, holder) }
holder.imageViewDelete.setOnClickListener { deleteItem(position) }
// holder.itemView.setOnClickListener { goToDetail(产品) } }
private fun getTotal(): Double {
var total = 0.0
for (p in products) {
total = total + (p.quantity!! * p.price)
}
return total
}
private fun getIndexOf(idProduct: String): Int {
var pos = 0
for (p in products) {
if (p.id == idProduct) {
return pos
}
pos++
}
return -1
}
private fun deleteItem(position: Int) {
products.removeAt(position)
notifyItemRemoved(position)
notifyItemRangeRemoved(position, products.size)
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
private fun addItem(product: Product, holder: ShoppingBagViewHolder) {
val index = getIndexOf(product.id!!)
product.quantity = product.quantity!! + 1
products[index].quantity = product.quantity
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.quantity!! * product.price}$"
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
private fun removeItem(product: Product, holder: ShoppingBagViewHolder) {
if (product.quantity!! > 1) {
val index = getIndexOf(product.id!!)
product.quantity = product.quantity!! - 1
products[index].quantity = product.quantity
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.quantity!! * product.price}$"
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
}
private fun goToDetail(product: Product) {
val i = Intent(context, ClientProductsDetailActivity::class.java)
i.putExtra("product", product.toJson())
context.startActivity(i)
}
class ShoppingBagViewHolder(view: View): RecyclerView.ViewHolder(view) {
val textViewName: TextView
val textViewPrice: TextView
val textViewCounter: TextView
val imageViewProduct: ImageView
val imageViewAdd: ImageView
val imageViewRemove: ImageView
val imageViewDelete: ImageView
init {
textViewName = view.findViewById(R.id.textview_name)
textViewPrice = view.findViewById(R.id.textview_price)
textViewCounter = view.findViewById(R.id.textview_counter)
imageViewProduct = view.findViewById(R.id.imageview_product)
imageViewAdd = view.findViewById(R.id.imageview_add)
imageViewRemove = view.findViewById(R.id.imageview_remove)
imageViewDelete = view.findViewById(R.id.imageview_delete)
}
}
ClientShoppingBagActivity
class ClientShoppingBagActivity : AppCompatActivity() {
var recyclerViewShoppingBag: RecyclerView? = null
var textViewTotal: TextView? = null
var buttomNext: Button? = null
var toolbar: Toolbar? = null
var adapter: ShoppingBagAdapter? = null
var sharedPref: SharedPref? = null
var gson = Gson()
var selectedProducts = ArrayList<Product>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_client_shopping_bag)
sharedPref = SharedPref(this)
recyclerViewShoppingBag = findViewById(R.id.recyclerview_shopping_bag)
textViewTotal = findViewById(R.id.textview_total)
buttomNext = findViewById(R.id.btn_next)
toolbar = findViewById(R.id.toolbar)
toolbar?.setTitleTextColor(ContextCompat.getColor(this, R.color.white))
toolbar?.title = "Tu orden"
setSupportActionBar(toolbar)
supportActionBar?.setDisplayHomeAsUpEnabled(true)
recyclerViewShoppingBag?.layoutManager = LinearLayoutManager(this)
getProductsFromSharedPref()
buttomNext?.setOnClickListener{goToAddressList() }
}
private fun goToAddressList(){
val i = Intent(this, ClientAddressListActivity::class.java)
startActivity(i)
}
fun setTotal(total: Double){
textViewTotal?.text = "${total}$"
}
private fun getProductsFromSharedPref() {
if (!sharedPref?.getData("order").isNullOrBlank()) { // EXISTE UNA ORDEN EN SHARED PREF
val type = object : TypeToken<ArrayList<Product>>() {}.type
selectedProducts = gson.fromJson(sharedPref?.getData("order"), type)
adapter = ShoppingBagAdapter(this, selectedProducts)
recyclerViewShoppingBag?.adapter = adapter
}
}
link 视频 其中应用是运行 所以你可以看到错误在哪里 https://youtu.be/iUNCo5aCLLY
这里有一个更明确的视频关于问题的问题，我真的希望你可以帮助我https://youtu.be/T262TUQxRVw
现在我将继续附上图片，这样你就可以看到错误的完整描述，尽管我也可以在下面看到它们
image 1 where is the complete error
in this image I specify the error line
in this image I specify the other line of the error
in this image I specify the other line of the error
in this image I specify the other line of the error
完整的错误描述
2022-05-16 16:28:46.508 6163-6163/com.blader.domicilios E/AndroidRuntime：致命异常：main 进程：com.blader.domicilios，PID：6163 java.lang.RuntimeException: 无法启动 activity ComponentInfo{com.blader.domicilios/com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity}: java.lang.NullPointerException 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449) 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) 在 android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 在 android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 在 android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066) 在 android.os.Handler.dispatchMessage(Handler.java:106) 在 android.os.Looper.loop(Looper.java:223) 在 android.app.ActivityThread.main(ActivityThread.java:7656) 在 java.lang.reflect.Method.invoke（本机方法） 在 com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 原因：java.lang.NullPointerException 在 com.blader.domicilios.adapters.ShoppingBagAdapter.getTotal(ShoppingBagAdapter.kt:57) 在 com.blader.domicilios.adapters.ShoppingBagAdapter.(ShoppingBagAdapter.kt:25) 在 com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity.getProductsFromSharedPref(ClientShoppingBagActivity.kt:73) 在 com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity.onCreate(ClientShoppingBagActivity.kt:52) 在 android.app.Activity.performCreate(Activity.java:8000) 在 android.app.Activity.performCreate(Activity.java:7984) 在 android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309) 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422) 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) 在 android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 在 android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 在 android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066) 在 android.os.Handler.dispatchMessage(Handler.java:106) 在 android.os.Looper.loop(Looper.java:223) 在 android.app.ActivityThread.main(ActivityThread.java:7656) 在 java.lang.reflect.Method.invoke（本机方法）
我真的很担心你不能帮我能按时交作业，我的时间真的很少**
您还没有发布完整的堆栈跟踪，所以我只是猜测，但我认为是这一行：
total = total + (p.quantity!! * p.price)
quantity 是可以为 null 的类型，您应该 null-check 那些以确保它们 not null 在你做任何事情之前他们。 !! 始终是一个不好的迹象，它的意思是“我保证这永远不会为空”，我的猜测是 quantity is null 这就是它崩溃的原因。 （这就是为什么你应该始终处理空值并且永远不要使用 !! 除非你完全知道你在做什么以及为什么需要它）
你或许可以用这个来解决它：
private fun getTotal(): Double {
var total = 0.0
for (p in products) {
if (p.quantity != null) total += p.quantity * p.price
}
return total
}
或者如果您愿意：
private fun getTotal(): Double =
products.sumByDouble { p -> (p.quantity ?: 0) * p.price }
我不知道你的应用程序是否明显存在任何其他问题，但希望这应该能阻止你获得特定的 NullPointerException
这是现在的错误所在，当我再次尝试添加产品时应用程序关闭，我会再次附上截图 here I select where the error marks, so that you can see which is the line that sends me the error, once thanks for helping me
enter image description here
再次向我发送错误的代码****
import android.app.Activity
import android.content.Intent
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.blader.domicilios.R
import com.blader.domicilios.activities.client.products.detail.ClientProductsDetailActivity
import com.blader.domicilios.activities.client.shopping_bag.ClientShoppingBagActivity
import com.blader.domicilios.models.Product
import com.blader.domicilios.utils.SharedPref
import com.bumptech.glide.Glide
class ShoppingBagAdapter(val context: Activity, val products: ArrayList<Product>): RecyclerView.Adapter<ShoppingBagAdapter.ShoppingBagViewHolder>() {
val sharedPref = SharedPref(context)
val TAG = "ShoppingBag"
init {
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ShoppingBagViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.cardview_shopping_bag, parent, false)
return ShoppingBagViewHolder(view)
}
override fun getItemCount(): Int {
return products.size
}
override fun onBindViewHolder(holder: ShoppingBagViewHolder, position: Int) {
val product = products[position] // CADA UNA DE LAS CATEGORIAS
holder.textViewName.text = product.name
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.price * product.quantity!!}"
Glide.with(context).load(product.image1).into(holder.imageViewProduct)
holder.imageViewAdd.setOnClickListener { addItem(product, holder) }
holder.imageViewRemove.setOnClickListener { removeItem(product, holder) }
holder.imageViewDelete.setOnClickListener { deleteItem(position) }
// holder.itemView.setOnClickListener { goToDetail(product) }
}
private fun getTotal(): Double =
products.sumByDouble { p -> (p.quantity ?: 0) * p.price }
private fun getIndexOf(idProduct: String): Int {
var pos = 0
for (p in products) {
if (p.id == idProduct) {
return pos
}
pos++
}
return -1
}
private fun deleteItem(position: Int) {
products.removeAt(position)
notifyItemRemoved(position)
notifyItemRangeRemoved(position, products.size)
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
private fun addItem(product: Product, holder: ShoppingBagViewHolder) {
val index = getIndexOf(product.id!!)
product.quantity = product.quantity!! + 1
products[index].quantity = product.quantity
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.quantity!! * product.price}$"
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
private fun removeItem(product: Product, holder: ShoppingBagViewHolder) {
if (product.quantity!! > 1) {
val index = getIndexOf(product.id!!)
product.quantity = product.quantity!! - 1
products[index].quantity = product.quantity
holder.textViewCounter.text = "${product.quantity}"
holder.textViewPrice.text = "${product.quantity!! * product.price}$"
sharedPref.save("order", products)
(context as ClientShoppingBagActivity).setTotal(getTotal())
}
}
private fun goToDetail(product: Product) {
val i = Intent(context, ClientProductsDetailActivity::class.java)
i.putExtra("product", product.toJson())
context.startActivity(i)
}
class ShoppingBagViewHolder(view: View): RecyclerView.ViewHolder(view) {
val textViewName: TextView
val textViewPrice: TextView
val textViewCounter: TextView
val imageViewProduct: ImageView
val imageViewAdd: ImageView
val imageViewRemove: ImageView
val imageViewDelete: ImageView
init {
textViewName = view.findViewById(R.id.textview_name)
textViewPrice = view.findViewById(R.id.textview_price)
textViewCounter = view.findViewById(R.id.textview_counter)
imageViewProduct = view.findViewById(R.id.imageview_product)
imageViewAdd = view.findViewById(R.id.imageview_add)
imageViewRemove = view.findViewById(R.id.imageview_remove)
imageViewDelete = view.findViewById(R.id.imageview_delete)
}
}