Develop Reference

How to extend 'TextView' by two properties with the use of 'Tag'?

I try to program a game with 12 coins in Android/Kotlin.
The coins are made by a TextView and created at runtime. All works fine so far.
fun createCoin(coinNumber: Int) : TextView {
val createdCoin = AppCompatTextView(this)
createdCoin.background = ContextCompat.getDrawable(this, R.drawable.simple_circle)
createdCoin.gravity = Gravity.CENTER
createdCoin.layoutParams = FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT)
createdCoin.text = (coinNumber +1).toString()
createdCoin.textSize = 20F
createdCoin.setTextColor(Color.BLACK)
createdCoin.tag = ??????
return createdCoin
}
But now I need to save 2 more informations with each coin.
posIndex:Int
state:coinState
The enum:
enum class coinState{
UNKNOWN,
TRUE,
FALSE,
Up,
DOWN
}
Is there a possibility to store these two informations in an object/class and assign it to the tag in TextView. Or is there another simple way?
Thanks for your help
Jan

Way to save 2 object without any effort and additional classes :
tag = Pair(5, coinState.DOWN)

There is a simple way.
You can concatenate strings with a special delimeter, and then just read it as array of params by splitting by delimeter.
You can also use Pair like in answer above. In case if there are no parameters more than 2.
Or you can create own model
data class CoinParams(var name1: Type1, var name2: Type2, ....)
createdCoin.tag = CoinParams(1, "Some value", ...)
val params: CoinParams = createdCoin.tag as CoinParams
Example of string:
createdCoin.tag = "$value1||$value2"
params = createdCoin.tag.split("||")

tex.tag=Triple("x",3,5)
var tagLogin= loginAsTv.tag as Triple<String,Int,Int>
println("tag ${tagLogin.first}")
You can try this.. or You ca set it on the basis of pattern
eg tag= position_coinindex

How can I print while loop results in textView in Kotlin

I have a "for-loop" in Kotlin which is going to run my code 6 times.
I also have a textView on the app and want to see these 6 results shown there.
I can easily println() the results.
However, If I set the text of textView to these results, it only gets the last result.
What I like to do printing out all 5 results in textView (suggestedNums ) as each result is a separate line.
Is it even possible?
Any help appreciated.
Thanks.
for (i in 1..6) {
val s: MutableSet<Int> = mutableSetOf()
//create 5 numbers from numbers
while (s.size < 5) {
val rnd = (numbers).random()
s.add(rnd)
}
// remove all 5 random numbers from numbers list.
numbers.removeAll(s)
// sort 5 random numbers and println
println(s.sorted())
// set suggestedNums text to "s"
suggestedNums.text = s.sorted().toString()
}

You can do it in 2 ways
replace
suggestedNums.text = s.sorted().toString()
with
suggestedNums.text = suggestedNums.text.toString() + "\n" + s.sorted().toString()
Create a string and append the results with "\n" and set the text outside the for loop

Kotlin check for words in string

I have a NSFW class that scans texts like item names and descriptions against a list of known NSFW-words.
That would be the best approach to test a list of strings like
let nsfw = listof(
"badword",
"curseword",
"ass",
... 200+ more
)
against a string like:
This is the text that contains a badword // returns true
Please note that i need to check for full words. not parts of words.
so the sentence:
The grass is grean // returns false
Because grass is not a bad word.
Ive tried something like this but it doesnt check for full words.
val result = nsfw.filter { it in sentence.toLowerCase() }

You may build a regex like
\b(?:word1|word2|word3...)\b
See the regex demo. Then, use it with the Regex.containsMatchIn method:
val nsfw = listOf(
"badword",
"curseword",
"ass"
)
val s1 = "This is the text that contains a badword"
val s2 = "The grass is grean"
val rx = Regex("\\b(?:${nsfw.joinToString(separator="|")})\\b")
println(rx.containsMatchIn(s1)) // => true
println(rx.containsMatchIn(s2)) // => false
See this Kotlin demo.
Here, nsfw.joinToString(separator="|") joins the words with a pipe (the alternation operator) and the "\\b(?:${nsfw.joinToString(separator="|")})\\b" creates the correct regex.
If your words may contain special regex metacharacters, like +, ?, (, ), etc., you need to "preprocess" the nsfw values with the Regex.escape method:
val rx = Regex("\\b(?:${nsfw.map{Regex.escape(it)}.joinToString("|")})\\b")
^^^^^^^^^^^^^^^^^^^^^^
See the Kotlin demo.
AND one more thing: if the keywords may start/end with chars other than letters, digits and underscores, you cannot rely on \b word boundaries. You may
Use whitespace boundaries: val rx = Regex("(?<!\\S)(?:${nsfw.map{Regex.escape(it)}.joinToString("|")})(?!\\S)")
Use unambiguous word boundaries: val rx = Regex("(?<!\\w)(?:${nsfw.map{Regex.escape(it)}.joinToString("|")})(?!\\w)")

You can use split() on the string that you want to check, with space as a delimiter, so you create a list of its words, although this does not always guarantee that all words will be extracted successfully, since there could exist other word separators like dots or commas etc. If that suits you, do this:
val nsfw = listOf(
"badword",
"curseword",
"ass"
)
val str = "This is the text that contains a badword"
val words = str.toLowerCase().split("\\s+".toRegex())
val containsBadWords = words.firstOrNull { it in nsfw } != null
println(containsBadWords)
will print
true
If you want a list of the "bad words":
val badWords = words.filter { it in nsfw }

Kotlin: SumbyDouble returning additional decimals

I am summing double value from arraylist its giving additional decimals as 99999, how to fix this, please guide
ex
class ExDet{var expName:String ="",var expAmount:Double = 0.0}
val arrayList = ArrayList<ExDet>()
arrayList.add(ExDet("Abc 1",45.66))
arrayList.add(ExDet("DEF 1",10.0))
arrayList.add(ExDet("Lee 1",600.89))
arrayList.add(ExDet("Ifr 1",200.9))
var amt = arrayList.sumByDouble{ it.expAmount }
Expected Value of Amount is :
Amt = 857.45
But it returns
Amt = 857.4499999
Sample Code to Test
data class ExDet(var expName:String ="" ,var expAmount:Double=0.0)
fun main(args: Array<String>) {
val arrayList = ArrayList<ExDet>()
arrayList.add(ExDet("Abc 1",45.66))
arrayList.add(ExDet("DEF 1",10.0))
arrayList.add(ExDet("Lee 1",600.89))
arrayList.add(ExDet("Ifr 1",200.9))
var amt = arrayList.sumByDouble{ it.expAmount }
println("Amount is : $amt")
}

The issue you are confronted with is that floating point numbers are build on top of base 2, not base 10.
Think how you can easily represent a third as a fraction (1/3), but when you convert to decimal you get a repeating (recurring) number after the radix point (i.e. 0.33...). Some decimal numbers are recurring when represented in base-2, e.g. x.9. The computer has a finite number of bits, so the (base-2) number is truncated. All the truncation errors can add up.
You need to round to the required precision (e.g. round(x * 100) / 100).
If you are only interested in how it is displayed then you can use the format function with something like "%.2f".
String.format("%.2f", value)

How to append 2 strings in Kotlin?

I am trying to concatenate 2 String but not sure how to go about it.
this is my code:
val word = R.string.word
and i'm trying to append it with "$currentPage/5" inside the setText("$currentPage/5")
i tried to make it in this way setText("$word $currentPage/5")
and this way setText("${R.string.value} $currentPage/5")
and it did not work , it only shows me numbers not the text

try to use this:
val word = getString(R.string.word)
text_view.text = "$word $currentPage/5"
If you want to edit your value (e.g. current page) wrap it with {}
E.g.
val word = getString(R.string.word)
text_view.text = "$word ${currentPage/5}"
Remember to use proper kotlin syntax

In Kotlin, the concatenation of string can be done by **interpolation/templates**.
val a = "Its"
val b = "Kotlin!"
val c = "$a $b"
The output will be Its Kotlin!
Or we can alson do concatenate using the **+ / plus() operator**:
val a = "String"
val b = "Concatenate"
val c = a + b
val d =a.plus(b)
print(c)
The output will be: StringConcatenate
print(d)
The output will be: StringConcatenate
Or you can concatenate using the StringBuilder which is a normal way to do that.

To concatenate two string, we could do
val concatenatedWord = "${resources.getString(R.string.value)}:
${number/3}."
If R.string.value was "The result" and number was 15, value of concatenatedWord will be "The result: 5."
Or we could also concatenate using the + operator or using StringBuilder.
But if you do
textView.text = "${resources.getString(R.string.value)}: ${number/3}."
AS will warn "Do not concatenate text displayed with setText." so, in the case of setting concatenated text in textview, consider using
String.format("%s: %d.", resources.getString(R.string.value):
number/3)

As a future resource and answer why the accepted answer works:-
String Templates:-
Strings may contain template expressions, i.e. pieces of code that are evaluated and whose results are concatenated into the string.
How to implement these?
A template expression should start with a dollar sign ($) and consists of either a simple name:
when the expression is a simple variable.
val i = 10
println("i = $i") // prints "i = 10"
or else arbitrary expression in curly braces:
val s = "abc"
println("$s.length is ${s.length}") // prints "abc.length is 3"
Note :- Templates are supported both inside raw strings and inside escaped strings.

val nameOfAnimal = "fish"
val speciesClass = "is an Aquatic Vertebrate"
println(nameOfAnimal.plus(speciesClass))
println(nameOfAnimal+speciesClass)
println("$nameOfAnimal $speciesClass")
Results:
fishis an Aquatic Vertebrate
fishis an Aquatic Vertebrate
fish is an Aquatic Vertebrate