I am trying to print by making it a string in the class. I am trying not to have any print lines in the class at all. I can't figure out how to not have the print lines in my printBoard method.
class MakeString() {
fun printThis(): String {
var line = arrayOf("hello","printMe")
var addThis = "there"
for (element in array) {
println()
}
return line.toString()
}
override fun toString(): String {
return """
${printThis()}
""".trimIndent()
}
}
You can use a StringBuilder to build the output string:
class Puzzle(var rows :Int,var cols: Int) {
fun printBoard(): String {
var emptyCell = '.'
var board = Array(rows) { Array(cols) { emptyCell } }
val builder = StringBuilder()
for (row in 0 until board.size) {
for (col in 0 until board[row].size) {
builder.append(board[row][col])
}
builder.append('\n')
}
return builder.toString()
}
override fun toString(): String {
return """
${printBoard()}
""".trimIndent()
}
}
fun main () {
var wordss = Puzzle(45, 45)
println(wordss.printBoard())
}
Related
I was practicing data structure algorithm and made a Union - Find solution for the question.
The problem is, I think the code seems ok, but when I run it on Xcode playground, it shows different answers for the same input.
For example, I put an array [4, 6, 15, 35] in the function largestComponentSize, then it shows 2, 3, or 4 as the answer. I don't understand what's happening behind.
class Solution {
var uf = UnionFind()
func largestComponentSize(_ nums: [Int]) -> Int {
var maxNum:Int = 0
var numFactorMap = [Int:Int]()
var factorAdded = Set<Int>()
for num in nums {
var pFactors = getPrimeFactors(num)
numFactorMap[num] = pFactors[0]
for (i, val) in pFactors.enumerated() {
if !factorAdded.contains(val) {
uf.addSet(val)
factorAdded.insert(val)
}
if i > 0 {
uf.union(pFactors[i-1], val)
}
}
}
var groupCountMap = [Int:Int]()
for num in nums {
var groupId = uf.find(numFactorMap[num]!)!
if groupCountMap.keys.contains(groupId) {
groupCountMap[groupId]! += 1
} else {
groupCountMap[groupId] = 1
}
maxNum = max(maxNum, groupCountMap[groupId]!)
}
return maxNum
}
func getPrimeFactors(_ num: Int) -> [Int] {
var ans:Set<Int> = []
if num == 1 {
return []
}
var crrNum = num
var deno = 2
while crrNum >= deno {
if crrNum % deno == 0 {
ans.insert(deno)
crrNum = crrNum / deno
} else {
deno = deno + 1
}
}
return Array(ans)
}
class UnionFind {
var index = [Int: Int]()
var parent: [Int]
var size: [Int]
init() {
parent = []
size = []
}
func addSet(_ ele: Int) {
index[ele] = parent.count
parent.append(parent.count)
size.append(1)
}
func getSetSize(_ ele: Int) -> Int {
if let found = find(ele) {
return size[found]
}
return 0
}
func find(_ ele: Int) -> Int? {
if let indexOfEle = index[ele] {
if parent[indexOfEle] == indexOfEle {
return indexOfEle
} else {
if let found = find(parent[indexOfEle]) {
parent[indexOfEle] = found
}
return parent[indexOfEle]
}
} else {
return nil //never come here
}
}
func union(_ first: Int, _ second: Int) {
guard let indexOfFirst = index[first], let indexOfSecond = index[second] else {
return
}
if parent[indexOfFirst] == parent[indexOfSecond] {
return
}
var indexOfLarger = indexOfFirst
var indexOfSmaller = indexOfSecond
if size[indexOfFirst] < size[indexOfSecond] {
indexOfLarger = indexOfSecond
indexOfSmaller = indexOfFirst
}
parent[indexOfSmaller] = indexOfLarger
size[indexOfLarger] += size[indexOfSmaller]
return
}
}
}
var sol = Solution()
var nums = [4, 6, 15, 35]
var ans = sol.largestComponentSize(nums)
Thank you for your help in advance!
I just tried it on Xcode playground.
I created a fragment that in the onActivityCreated method fetches Firebase data by limiting the query to a calendar date. Then I place Observers on my LiveData that are inside my ViewModel and that will deliver the list to my Adapter.
If I add, remove or update items in the same list, the changes are sent to firebase and the adapter reflects them on the screen. It works ok.
But, I am trying to develop a filter button, which will basically change the deadline date for the Firebase query. When I select a particular filter, the viewModel needs to retrieve the data from Firebase limited to the filter date. This generates a new list, having a different size from the previous one.
However, when the query occurs, the Adapter's getItemCount() method stores the size of the last list. This fact confuses the Adapter and the functions notifyItemInserted and notifyItemRemoved end up making confusing animations on the screen after changing the filter. I dont know whats is wrong.
How can I correctly observes LiveData and tell the adapter? Am I making a mistake in the MVVM architecture or forgetting some function?
My Fragment:
class HistoryFragment : Fragment(), OnItemMenuRecyclerViewClickListener {
private lateinit var mSecurityPreferences: SecurityPreferences
private lateinit var viewModel: BalancesViewModel
private lateinit var adapter: BalancesAdapter
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
setHasOptionsMenu(true)
viewModel = ViewModelProvider(this).get(BalancesViewModel::class.java)
adapter = BalancesAdapter(requireContext())
mSecurityPreferences = SecurityPreferences(requireContext())
return inflater.inflate(R.layout.fragment_history, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
setupFilter()
//Setup adapter
adapter.listenerMenu = this
recycler_view_history.adapter = adapter
//Fetch data based in filter by date
viewModel.fetchBalances(mSecurityPreferences.getStoredLong(FILTER_DATE))
// Put logic to listen RealTimeUpdates
viewModel.getRealTimeUpdates(mSecurityPreferences.getStoredLong(FILTER_DATE))
viewModel.balances.observe(viewLifecycleOwner, Observer {
adapter.setBalances(it)
})
viewModel.balance.observe(viewLifecycleOwner, Observer {
adapter.addBalance(it)
})
}
override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
inflater.inflate(R.menu.history_menu_filter, menu)
super.onCreateOptionsMenu(menu, inflater)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
when (item.itemId) {
R.id.item_menu_filter_this_month -> {
updateFilter(THIS_MONTH)
}
R.id.item_menu_filter_two_months -> {
updateFilter(TWO_MONTHS)
}
R.id.item_menu_filter_last_six_months -> {
updateFilter(LAST_SIX_MONTHS)
}
R.id.item_menu_filter_all -> {
updateFilter(ALL_MONTHS)
}
}
return super.onOptionsItemSelected(item)
}
private fun setupFilter() {
var filterOption = mSecurityPreferences.getStoredLong(FILTER_DATE)
if (filterOption == 0L){
filterOption = HandleDate.getLongToFilter(LAST_SIX_MONTHS)
mSecurityPreferences.storeLong(FILTER_DATE, filterOption)
}
}
private fun updateFilter(filterOption: Int){
val newFilterOption = HandleDate.getLongToFilter(filterOption)
mSecurityPreferences.storeLong(FILTER_DATE, newFilterOption)
updateUI()
}
private fun updateUI(){
viewModel.fetchBalances(mSecurityPreferences.getStoredLong(FILTER_DATE))
viewModel.getRealTimeUpdates(mSecurityPreferences.getStoredLong(FILTER_DATE))
}
}
My ViewModel:
class BalancesViewModel : ViewModel() {
private val userReference = FirebaseAuth.getInstance().currentUser!!.uid
private val dbUserReference = FirebaseDatabase.getInstance().getReference(userReference)
private val _balances = MutableLiveData<List<Balance>>()
val balances: LiveData<List<Balance>>
get() = _balances
private val _balance = MutableLiveData<Balance>()
val balance: LiveData<Balance>
get() = _balance
private val _result = MutableLiveData<Exception?>()
val result: LiveData<Exception?>
get() = _result
fun addBalance(balance: Balance) {
balance.id = dbUserReference.push().key
dbUserReference.child(NODE_BALANCES).child(balance.id!!).setValue(balance)
.addOnCompleteListener {
if (it.isSuccessful) {
_result.value = null
} else {
_result.value = it.exception
}
}
}
private val childEventListener = object : ChildEventListener {
override fun onCancelled(error: DatabaseError) {
}
override fun onChildMoved(snapshot: DataSnapshot, p1: String?) {
}
override fun onChildChanged(snapshot: DataSnapshot, p1: String?) {
val balance = snapshot.getValue(Balance::class.java)
balance?.id = snapshot.key
_balance.value = balance
}
override fun onChildAdded(snapshot: DataSnapshot, p1: String?) {
val balance = snapshot.getValue(Balance::class.java)
balance?.id = snapshot.key
_balance.value = balance
}
override fun onChildRemoved(snapshot: DataSnapshot) {
val balance = snapshot.getValue(Balance::class.java)
balance?.id = snapshot.key
balance?.isDeleted = true
_balance.value = balance
}
}
fun getRealTimeUpdates(longLimitDate: Long) {
dbUserReference.child(NODE_BALANCES).orderByChild(COLUMN_DATE_MILLI)
.startAt(longLimitDate.toDouble()).addChildEventListener(childEventListener)
}
fun fetchBalances(longLimitDate: Long) {
dbUserReference.child(NODE_BALANCES).orderByChild(COLUMN_DATE_MILLI)
.startAt(longLimitDate.toDouble())
.addListenerForSingleValueEvent(object : ValueEventListener {
override fun onCancelled(error: DatabaseError) {}
override fun onDataChange(snapshot: DataSnapshot) {
if (snapshot.exists()) {
val listBalances = mutableListOf<Balance>()
for (balanceSnapshot in (snapshot.children)) {
val balance = balanceSnapshot.getValue(Balance::class.java)
balance?.id = balanceSnapshot.key
balance?.let { listBalances.add(it) }
}
listBalances.sortByDescending { it.dateMilli }
_balances.value = listBalances
}
}
})
}
fun updateBalance(balance: Balance) {
dbUserReference.child(NODE_BALANCES).child(balance.id!!).setValue(balance)
.addOnCompleteListener {
if (it.isSuccessful) {
_result.value = null
} else {
_result.value = it.exception
}
}
}
fun deleteBalance(balance: Balance) {
dbUserReference.child(NODE_BALANCES).child(balance.id!!).setValue(null)
.addOnCompleteListener {
if (it.isSuccessful) {
_result.value = null
} else {
_result.value = it.exception
}
}
}
My Adapter:
class BalancesAdapter(private val context: Context) :
RecyclerView.Adapter<BalancesAdapter.BalanceViewModel>() {
private var balances = mutableListOf<Balance>()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
BalanceViewModel(
LayoutInflater.from(parent.context)
.inflate(R.layout.item_recyclerview_balance, parent, false)
)
override fun getItemCount() = balances.size
override fun onBindViewHolder(holder: BalanceViewModel, position: Int) {
holder.view.text_view_value_balance_item.text = balances[position].value
holder.view.text_view_date_item.text = balances[position].date
}
fun setBalances(balances: List<Balance>) {
this.balances = balances as MutableList<Balance>
notifyDataSetChanged()
}
fun addBalance(balance: Balance) {
val index = balances.indexOf(balance)
if (!balances.contains(balance)) {
balances.add(balance)
notifyItemInserted(index)
} else {
if (balance.isDeleted) {
balances.removeAt(index)
notifyItemRemoved(index)
} else {
balances[index] = balance
}
}
notifyItemRangeChanged(index, itemCount)
}
class BalanceViewModel(val view: View) : RecyclerView.ViewHolder(view)
}
Tnks for your attention.
Okay, it's been 4 days since I asked this question and after feeling a little frustrated with the project I come back here on StackOverFlow to post my own answer.
The problematic issue within the code I showed is in my Adapter's addBalance method.
When I created the Balance data model, I set the isDeleted attribute to identify that it was deleted. Upon entering Firebase it receives a NULL value and therefore it ceases to exist.
Then, as I have two listeners (one defined in the addListenerForSingleValueEvent method and the other defined in the addChildEventListener method), one ends up triggering the other when there is a change in the Firebase data, but I don't want to go into detail on that issue. The fact is that I checked that my addBalance method was being called after I deleted an object, causing that object to be inserted back into the Adapter's data list, even before the removal operation ended in Firebase.
So I changed the logic of my method to make sure that my object was deleted and only included it in my Adapter list after checking the isDeleted attribute.
fun dealWithBalance(balance: Balance){
val index = balances.indexOf(balance)
if(balance.isDeleted && balances.contains(balance)){
balances.removeAt(index)
notifyItemRemoved(index)
} else if(!balance.isDeleted && !balances.contains(balance)){
balances.add(balance)
} else if(index >= 0){
balances[index] = balance
notifyItemChanged(index)
}
}
I renamed addBalance to dealWithBalance...
Here's the code in Kotlin.
file1
fun main() {
var player = Player("madrigal")
println(player.name)
printPlayerStatus(player)
println(player.name)
}
private fun printPlayerStatus(player: Player) {
println("${player.name} ")
}
file2
package com.bignerdranch.nyethack
import java.io.File
class Player(
_name: String,
var healthPoints: Int = 100,
var isBlessed: Boolean,
private val isImmortal: Boolean
) {
constructor(name: String) : this(name, isBlessed = true, isImmortal = false) {
if (name.toLowerCase() == "kar") healthPoints = 40
}
var name = _name
get() ="${field.capitalize()} of $hometown"
private set(value) {
field = value.trim()
}
val hometown: String = selectHometown()
init {
require(healthPoints > 0, { "healthPoints must be greater than zero." })
require(name.isNotBlank(), { "Player must have a name" })
}
private fun selectHometown(): String = File("data/towns.txt")
.readText()
.split('\n')
.shuffled()
.last()
fun castFireball(numFireballs: Int = 2) =
println("A glass of Fireball springs into existence. (x$numFireballs)")
fun formatHealthStatus() =
when (healthPoints) {
100 -> "is in excellent condition!"
in 90..99 -> "has a few scratches."
in 75..89 -> if (isBlessed) {
"has some minor wounds, but is healing quite quickly!"
} else {
"has some minor wounds."
}
in 15..74 -> "looks pretty hurt."
else -> "is in awful condition!"
}
fun auraColor(): String {
val auraVisible = isBlessed && healthPoints > 50 || isImmortal
val auraColor = if (auraVisible) "GREEN" else "NONE"
return auraColor
}
}
When I run it I get the results:
Madrigal of Boston
Madrigal of Boston
However, I expect to get the results without the empty string in the middle. Like this:
Madrigal of Boston
Madrigal of Boston
Madrigal of Boston
Then I rewrite the function printPlayerStatus as below :
private fun printPlayerStatus(player: Player) {
println(player.name)
}
Now the output is correct.
Actually I copy the code from the book. And according to the book the code should work fine.
Please, help me to understand why it happens and find my mistake.
Problem is solved. If I avoid working with file and make a simple list of strings, the output gets as expected.
I need to pass data to class from activity. I use interface, but i have problem with initialization.
My class:
class Methods {
fun processingResponse(finalMessage: String) {
var mcontext: Context? = null
var message : Message = Message()
var access = "Access Granted"
var out = "Logged"
var Stateconnect = false
var safetyCheck = 0
if (access in finalMessage) {
val msg = finalMessage.split("=", ":")
accessLevel = msg[0]
sessionId = msg[1].toInt()
safetyCheck = msg[2].toInt()
var namePlc = msg[3]
interfaceData.sendData("Connect")
//Stateconnect = true
} else if (out in finalMessage) {
interfaceData.sendData("Disconnect")
println("log out okey")
}
}}
My interface:
interface SendDataInterface {fun sendData(str: String )}
and My activity:
class LoginIn : AppCompatActivity(), SendDataInterface {
override fun sendData(str: String)
{
var handler = Handler(Looper.getMainLooper())
handler.post( Runnable() {
fun run() {
buttonChange(str)
}
})} fun buttonChange(str : String) {
if (str == "Connect") {
Connection.setBackgroundColor(Color.RED)
Connection.setText("Disconnection")
loadMaintenancePage()
} else if (str == "Disconnect") {
Connection.setBackgroundColor(Color.GREEN)
Connection.setText("Connection")
}
}
}
The error that i have is the interface isn't initialize.
How I can initialize the interface?
You have to create an instance of SendDataInterface in your class Methods.
var interfaceData:SendDtaInterface=Object:SendDtaInterface{
override fun sendData("Connect"){
}
}
interfaceData.sendDat("connect")enter code here
Example:
#noreturn func setOnlyPropertyGetterError(__function__: String) {
fatalError("\(__function__) is set-only")
}
var property: Property {
get {setOnlyPropertyGetterError(__FUNCTION__)}
set {//useful work}
}
Can we avoid having to pass __FUNCTION__?
I think this is what you want to achieve:
#noreturn func writeOnlyProperty(propertyName: String = __FUNCTION__) {
fatalError("Property \(propertyName) is write-only")
}
class Foo {
var blackHole: Int {
get { writeOnlyProperty() }
set { print("Consuming value \(newValue)") }
}
}
let foo = Foo()
foo.blackHole = 1 // Prints "Consuming value 1"
let bar = foo.blackHole // Produces fatal error "Property blackHole is write-only"