Is it possible to use a method or something else rather â%.6fâ.format(value) in order to achieve the same thing?
this is my code :
println("%.6f".format(value))
I'll want to make it more dynamic and readable
You can always use
String.format("%.6f", value)
But you can extract the format in a variable
val FORMAT_FLOAT = "%.6f"
println(String.format(FORMAT_FLOAT, value))
It depends on your preferences. Good luck!
You can make it an Extension Function for your project, which is a very powerful feature of Kotlin, the function is like this:
fun Double.roundDecimal(digit: Int) = "%.${digit}f".format(this)
Just put it in a Kotlin file But Outside The Class, then you can access it everywhere in your project:
fun main() {
val number = 0.49555
println(number.roundDecimal(2))
println(number.roundDecimal(3))
}
Output:
0.50
0.496
you can use DecimalFormat class to round a given number. More info
i.e.
val num = 1.345672
val df = DecimalFormat("#.######")
df.roundingMode = RoundingMode.CEILING
println(df.format(num))
Related
I am facing an issue where I need to do some calculations with a number like for example 5000,00 multiplied it by (1,025^3).
So in this case 5000,00 * (1,025^3) = 5385,45
So my question is, how can I format the number 5385,45 to be like 5.385,45 using decimal format maybe?
I tried by myself and I did this piece of code that outputs 5385,45 in the app but not 5.385,45
var interestValue = (5000,00*(Math.pow(1.025,yearValue)))
val number = java.lang.Double.valueOf(interestValue)
val dec = DecimalFormat("#,00")
val credits = dec.format(number)
vValueInterest.text = credits
This is the format you need:
val dec = DecimalFormat("#,###.##")
will print:
5.384,45
if you need always exactly 2 digits after the decimal point:
val dec = DecimalFormat("#,###.00")
val num = 1.34567
val df = DecimalFormat("#.##")
df.roundingMode = RoundingMode.CEILING
println(df.format(num))
When you run the program, the output will be:
1.34
Check:
https://www.programiz.com/kotlin-programming/examples/round-number-decimal
The "most Kotlin-esque" way I found to do this sort of formatting is:
"%,.2f".format(Locale.GERMAN, 1234.5678) // => "1.234,57"
"%,.2f".format(Locale.ENGLISH, 1234.5678) // => "1,234.57"
"%,.2f".format(1234.5678) // => "1,234.57" for me, in en_AU
Note though that even though this is Kotlin's own extension method on String, it still only works on the JVM.
For those looking for a multiplatform implementation (as I was), mp_stools is one option.
Used:
%.numberf
fun main(args: Array<String>) {
var A: Double
A = readLine()!!.toDouble()
var bla = A*A
var calculator = 3.14159 * bla
println("A=%.4f".format(calculator))
}
Try val dec = DecimalFormat("#.###,00"). For examples of DecimalFormat check this link.
How to get the string "hi" from the CharBuffer? toString() does not seem to work.
val a = CharBuffer.allocate(10);
a.put('h');
a.put('i');
val b = a.toString();
Variable states after running the code above:
CharBuffer is pretty low-level and really meant for I/O stuff, so it may seem illogical at first. In your example it actually returned a string containing remaining 8 bytes that you didn't set. To make it return your data you need to invoke flip() like this:
val a = CharBuffer.allocate(10);
a.put('h');
a.put('i');
a.flip()
val b = a.toString();
You can find more in the docs of the Buffer
For more typical use cases it is much easier to use StringBuilder:
val a = StringBuilder()
a.append('h')
a.append('i')
val b = a.toString()
Or even use a Kotlin util that wraps StringBuilder:
val b = buildString {
append('h')
append('i')
}
Let's say I have some arrays:
val a = arrayOf("Pushups", "Benchpress", "Squats")
val b = arrayOf("Pushups", "Squats", "Benchpress")
val c = arrayOf("Pushups", "Squats", "Sit Ups")
I essentially want to create a function to see if the two arrays have the same information, even if they're in a different order:
checkSameInfo(a,b) //Should return true
checkSameInfo(a,c) //Should return false
Is there a way of doing this, other than using a ton of for loops?
StackOverflow has been immensely helpful in the last two months of learning kotlin, so thanks to anyone who replies :)
a.sorted() == b.sorted()
Hope this helps.
I would just convert them to sets and then check if the contents are equal. Like this:
fun <T> checkSameInfo(arr1: Array<T>, arr2: Array<T>) = arr1.toSet() == arr2.toSet()
If you worked with lists instead of a arrays, you could use containsAll:
fun <T> checkSameInfo(list1: List<T>, list2: List<T>) =
list1.containsAll(list2) && list2.containsAll(list1)
In Kotlin, how to get the raw value of the String?
For example,
val value: String = "Adrian"
Expected result:
"Cannot find value: Adrian"
I am coming from Swift and I know in swift it works like this
let value: String = "Adrian"
print("Cannot find \(string.description): \(value)")
Another example in Swift,
let a: String = "b"
print("\(a.description) = \(a)"
///prints "a = b"
Im guessing a String extension is needed given I read the Kotlin String documentation and seems none of the choices provides the expected result.
A simple problem but I really can't solve it:(
This might help you. For this you have to use Kotlin reflection:
Example:
data class Person(val name:String)
fun main(){
val person = Person("Birju")
val prop = person::name
println("Property Name: ${prop.name}")
println("Property Value: ${prop.get()}")
}
How about
println("value :$value")
You don't need concatination operator(+) to concat strings in kotlin
I have been looking into scala primarily on how to build DSL similar to C# LINQ/SQL. Having worked with C# LINQ Query provider, it was easy to introduce our own custom query provider which translated LINQ query to our own proprietary data store scripts. I am looking something similar in scala for eg.
val query = select Min(Close), Max(Close)
from StockPrices
where open > 0
First of all is this even possible to achieve in scala using internal DSL.
Any thoughts/ideas in this regard is highly appreciated.
I am still new in scala space, but started looking into Scala MetaProgramming & Slick. My complaint with Slick is i want to align my DSL close to SQL query - similar to above syntax.
There is no way to have an internal DSL (with the currently release) that looks exactly like the example you provided.
Using a macro I still had from this answer, the closest I could get (relatively fast) was:
select(Min(StockPrices.Open), Max(StockPrices.Open))
.from(StockPrices)
A real solution would take quite some time to create. If you are willing to do that you could come quite far using macro's (not a simple topic).
If you really want the exact same syntax I recommend something like XText that allows you to create a DSL with an eclipse based editor for 'free'.
The code required for the above example (I did not include the mentioned macro):
trait SqlElement {
def toString(): String
}
trait SqlMethod extends SqlElement {
protected val methodName: String
protected val arguments: Seq[String]
override def toString() = {
val argumentsString = arguments mkString ","
s"$methodName($argumentsString)"
}
}
case class Select(elements: Seq[SqlElement]) extends SqlElement {
override def toString() = s"SELECT ${elements mkString ", "}"
}
case class From(table: Metadata) extends SqlElement {
private val tableName = table.name
override def toString() = s"FROM $tableName"
}
case class Min(element: Metadata) extends SqlMethod {
val methodName = "Min"
val arguments = Seq(element.name)
}
case class Max(element: Metadata) extends SqlMethod {
val methodName = "Max"
val arguments = Seq(element.name)
}
class QueryBuilder(elements: Seq[SqlElement]) {
def this(element: SqlElement) = this(Seq(element))
def from(o: Metadata) = new QueryBuilder(elements :+ From(o))
def where(element: SqlElement) = new QueryBuilder(elements :+ element)
override def toString() = elements mkString ("\n")
}
def select(args: SqlElement*) = new QueryBuilder(Select(args))
trait Column
object Column extends Column
object tables {
object StockPrices$ {
val Open: Column = Column
val Close: Column = Column
}
val StockPrices = StockPrices$
}
And then to use it:
import tables._
import StockPrices._
select(Min(StockPrices.Open), Max(StockPrices.Open))
.from(StockPrices)
.toString
That is an admirable project, but one that has been embarked upon and which is available in general release.
I'm talking about Slick, of course.
If Scala / Java interoperability is not too much of an issue for you, and if you're willing to use an internal DSL with a couple of syntax quirks compared to the syntax you have suggested, then jOOQ is growing to be a popular alternative to Slick. An example from the jOOQ manual:
for (r <- e
select (
T_BOOK.ID * T_BOOK.AUTHOR_ID,
T_BOOK.ID + T_BOOK.AUTHOR_ID * 3 + 4,
T_BOOK.TITLE || " abc" || " xy"
)
from T_BOOK
leftOuterJoin (
select (x.ID, x.YEAR_OF_BIRTH)
from x
limit 1
asTable x.getName()
)
on T_BOOK.AUTHOR_ID === x.ID
where (T_BOOK.ID <> 2)
or (T_BOOK.TITLE in ("O Alquimista", "Brida"))
fetch
) {
println(r)
}