I don't know how to get the string in readable format in my app. My code is:
val allergyList = recipeItem.allergies
allergyList.joinToString()
var allergyString: String = ""
for (allergy in allergyList) {
allergyList[1]
allergyString += " ${allergy}"
println(allergy.toString())
}
holder.recipeSearchPageAllergies.text = allergyString
When I print this I get the allergy string memory space?
Result for each one is something like this:
Allergy#4e8f238
How do I 'decode' it into something readable for a human? It should say 'nut allergy'.
you have some options. If you have the control over the Allergy source code,
you could override toString method:
class Allergy(val name: String) {
override fun toString(): String = "Allergy[name=${name}]"
}
println(Allergy("flowers"))
// Allergy[name=flowers]
also, you can make a data class of it. Data class has sane toString by default. It also has a few nice perks, like by default equals/hashCode generation, and deconstruction to components, allowing you to use it in destructing:
data class Allergy(val name: String)
println(Allergy("peanuts"))
// Allergy(name=peanuts)
otherwise, if you can't modify the source of the Allregy, you can make up an extension method for that:
class Allergy(val name: String)
fun Allergy.readable() = "Allergy[name=${name}]"
println(Allergy("cats").readable())
// Allergy[name=cats]
in your case, you could also make an extension method for collections of allergies to have the format you need:
fun Collection<Allergy>.readable() = joinToString { "Allergy[name=${it.name}]" }
println(
listOf(Allergy("cats"), Allergy("peanuts"), Allergy("flowers")).readable()
)
// Allergy[name=cats], Allergy[name=peanuts], Allergy[name=flowers]
// in your case:
holder.recipeSearchPageAllergies.text = recipeItem.allergies.readable()
// or just
holder.recipeSearchPageAllergies.text = recipeItem.allergies.joinToString { "Allergy[name=${it.name}]" }
You can make it simplier:
val allergiesStr = recipeItem.allergies.map { allergy ->
// your allergy name from allergy variable
}.joinToString(separator = " ")
Related
I have some code which looks like this, where param is of a data class type:
val options = if (param.language == null) {
param.copy(language = default())
} else {
param
}
Now, however, the language object has been moved into a hierarchy of nullable objects, so the check must look like this:
if (param.subObj?.nextObj?.language == null) { ... }
How do I use the copy idiom in this case?
One way to do this is:
val newParam = when {
param.subObj == null -> param.copy(subObj = SubObj(nextObj = NextObj(language = Language())))
param.subObj.nextObj == null -> param.copy(subObj = param.subObj.copy(nextObj = NextObj(language = Language())))
param.subObj.nextObj.language == null -> param.copy(subObj = param.subObj.copy(nextObj = param.subObj.nextObj.copy(language = Language())))
else -> param
}
I agree that this doesn't look very clean but this seems to be the only way to me, because at each step you need to check if the current property is null or not. If it is null, you need to use the default instance otherwise you need to make a copy.
Could you do something like this?
// you could create a DefaultCopyable interface if you like
data class SubObj(val prop1: Double? = null, val nextObj: NextObj? = null) {
fun copyWithDefaults() =
copy(prop1 = prop1 ?: 1.0, nextObj = nextObj?.copyWithDefaults() ?: NextObj())
}
data class NextObj(val name: String? = null) {
fun copyWithDefaults() = copy(name = name ?: "Hi")
}
I think you need a special function because you're not using the standard copy functionality exactly, you need some custom logic to define defaults for each class. But by putting that function in each of your classes, they all know how to copy themselves, and each copy function that works with other types can just call their default-copy functions.
The problem there though is:
fun main() {
val thing = SubObj(3.0)
val newThing = thing.copyWithDefaults()
println("$thing\n$newThing")
}
> SubObj(prop1=3.0, nextObj=null)
> SubObj(prop1=3.0, nextObj=NextObj(name=null))
Because nextObj was null in SubObj, it has to create one instead of copying it. But the real default value for name is null - it doesn't know how to instantiate one with the other defaults, that's an internal detail of NextObj. You could always call NextObj().copyWithDefaults() but that starts to look like a code smell to me - why isn't the default value for the parameter the actual default value you want? (There are probably good reasons, but it might mean there's a better way to architect what you're up to)
I have the next peace of code
#Test
fun `simple test`() {
val objectMapper = ObjectMapper()
.setSerializationInclusion(JsonInclude.Include.NON_NULL)
.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE)
.registerModule(KotlinModule())
val value = objectMapper.writeValueAsString(MyClass(myField1 = "something", myField2 = "something2"))
assertNotNull(value)
}
data class MyClass (
val myField1: String? = null,
#JsonProperty("my_field_2")
val myField2: String? = null,
)
the result of deserialization is next
{"my_field1":"something","my_field_2":"something2"}
Is it possible to configure objectMapper to automatically populate _ value, before digits in object property names, without specifying it in #JsonProperty?
Yes, this is possible using a PropertyNamingStrategy:
objectMapper.setPropertyNamingStrategy(PropertyNamingStrategies.SNAKE_CASE)
Note that you named your snake-case fields inconsistently, because there is my_field1 without a _ before the digit, and my_field_2 with a _ before the digit. The configuration above using PropertyNamingStrategies.SNAKE_CASE works fine for the first naming (like in my_field1).
If you want to use the second naming (like in my_field_2), then you would have to write your own naming strategy like this:
class MySnakeCaseStrategy : NamingBase() {
override fun translate(input: String?): String? =
if (input == null) null
else "([A-Z]+|[0-9]+)".toRegex().replace(input) { "_${it.groupValues[1]}".lowercase() }
}
That naming strategy can then be used to configure your object-mapper:
objectMapper.setPropertyNamingStrategy(MySnakeCaseStrategy())
I do not know if and how it would be possible to support both naming strategies at the same time.
I am trying to replace a few sub strings inside a string. But my code doesn't seem to work.
val listOfMaleWords = listOf(" him", " he", " his")
val listOfFemaleWords = listOf(" her", " she", " her")
fun modifyIdeaForGender(rawIdea : String, desiredGender : String): String {
var theRawIdea = rawIdea
if (desiredGender == "FEMALE") {
println("desired gender is FEMALE")
listOfMaleWords.forEachIndexed { index, element ->
theRawIdea.replace(element, listOfFemaleWords[index])
}
} else {
println("desired gender is MALE")
listOfFemaleWords.forEachIndexed { index, element ->
theRawIdea.replace(element, listOfMaleWords[index])
}
}
return theRawIdea
}
fun main() {
var sampleString : String = "Tell him, he is special"
println(modifyIdeaForGender(sampleString, "FEMALE"))
}
Expected Output :
"Tell her, she is special"
Current Output :
"Tell him, he is special" // no change
Whats wrong with my code? The current output doesn't replace the string characters at all.
replace returns a new String that you are discarding immediately. It does not mutate theRawIdea itself, so you should assign it back to theRawIdea yourself. For example:
theRawIdea = theRawIdea.replace(element, listOfFemaleWords[index])
Though this would modify theRawIdea as you desire, it wouldn't replace the pronouns correctly. Once it replaces the "him"s with "her"s, it would try to replace the "he"s with "she"s. But note that "he" a substring of "her"! So this would produce:
Tell sher, she is special
This could be fixed by reordering the lists, putting the "he"-"she" pair first, or by using regex, adding \b word boundary anchors around the words:
// note that you should not have spaces before the words if you decide to use \b
val listOfMaleWords = listOf("him", "he", "his")
val listOfFemaleWords = listOf("her", "she", "her")
...
theRawIdea = theRawIdea.replace("\\b$element\\b".toRegex(), listOfFemaleWords[index])
Note that this doesn't account for capitalisation or the fact that changing from female gender pronouns to male ones is inherently broken. Your current code would change all her to him. It would require some more complicated natural language processing to accurately do this task in general.
Taking all that into account, I've rewritten your code with zip:
fun modifyMaleIdeaToFemaleGender(rawIdea : String): String {
var theRawIdea = rawIdea
// if you really want to do the broken female to male case, then this would be
// listOfFemaleWords zip listOfMaleWords
// and the loop below can stay the same
val zipped = listOfMaleWords zip listOfFemaleWords
zipped.forEach { (target, replacement) ->
theRawIdea = theRawIdea.replace("\\b$target\\b".toRegex(), replacement)
}
return theRawIdea
}
You can also use fold to avoid reassigning theRawIdea:
fun modifyIdeaToFemaleGender(rawIdea : String): String {
val zipped = listOfMaleWords zip listOfFemaleWords
return zipped.fold(rawIdea) { acc, (target, replacement) ->
acc.replace("\\b$target\\b".toRegex(), replacement)
}
}
Your code assumes that the replace() method performs an in-place mutation of the string. However, the string with the replaced values are returned by the replace(). So you need to change your code to contain something like:
theRawIdea = theRawIdea.replace(element, listOfFemaleWords[index])
To do this, you will have to use a conventional loop instead of listOfMaleWords.forEachIndexed style looping.
for (i in 0 until result.size){ result[i].config= addConfig(taskNames!![i],processKeys!![i]) }
Here result is a list of class which has datamember config and tasNames and processKeys are list of string.
Is there a way in kotlin to map result.config with respective taskNames and processKeys without using traditional loop and mentioning length of result.I am new to kotlin.
class Process {
var processKey: String? = null
var task: List<Task>? = null}
class Task {
var taskName: String? = null
var processVariables: List<ProcessVariable>? = null}
class ProcessVariable {
var name: String? = null
var label: String? = null
var applicableValue: List<String>? = null}
Result is already present with datamember config pf type ProcessVariable
If I understand your problem correctly, you need to combine 3 lists.
So iterating over the lists may be easier to understand than some clever way of list transformations.
You can get rid of the traditional for loop, so you don't need to calculate the size of the loop:
result.forEachIndexed {
i, resultData -> resultData.config = addConfig(taskNames[i], processKeys[i])
}
If you want to combine two lists, you can use the zip method:
val configList = taskNames.zip(processKeys) {tsk, prc -> addConfig(tsk, prc)}
In your example, the result-object was already existing. Maybe it is easier to create new result-objects:
val results = configList.map {
Result(config = it)
}
I've refactored some legacy code within Spring Boot (2.1.2) system and migrated from java.util.Date to java.time based classes (jsr310). The system expects the dates in a ISO8601 formated string, whereas some are complete timestamps with time information (e.g. "2019-01-29T15:29:34+01:00") while others are only dates with offset (e.g. "2019-01-29+01:00"). Here is the DTO (as Kotlin data class):
data class Dto(
// ...
#JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ssXXX")
#JsonProperty("processingTimestamp")
val processingTimestamp: OffsetDateTime,
// ...
#JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-ddXXX")
#JsonProperty("orderDate")
val orderDate: OffsetDateTime,
// ...
)
While Jackson perfectly deserializes processingTimestamp, it fails with orderDate:
Caused by: java.time.DateTimeException: Unable to obtain OffsetDateTime from TemporalAccessor: {OffsetSeconds=32400},ISO resolved to 2018-10-23 of type java.time.format.Parsed
at java.time.OffsetDateTime.from(OffsetDateTime.java:370) ~[na:1.8.0_152]
at com.fasterxml.jackson.datatype.jsr310.deser.InstantDeserializer.deserialize(InstantDeserializer.java:207) ~[jackson-datatype-jsr310-2.9.8.jar:2.9.8]
This makes sense to me, since OffsetDateTime cannot find any time information necessary to construct the instant. If I change to val orderDate: LocalDate Jackson can successfully deserialize, but then the offset information is gone (which I need to convert to Instant later).
Question
My current workaround is to use OffsetDateTime, in combination with a custom deserializer (see below). But I'm wondering, if there is a better solution for this?
Also, I'd wish for a more appropriate data type like OffsetDate, but I cannot find it in java.time.
PS
I was asking myself if "2019-01-29+01:00" is a valid for ISO8601. However, since I found that java.time.DateTimeFormatter.ISO_DATE is can correctly parse it and I cannot change the format how the clients send data, I put aside this question.
Workaround
data class Dto(
// ...
#JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-ddXXX")
#JsonProperty("catchDate")
#JsonDeserialize(using = OffsetDateDeserializer::class)
val orderDate: OffsetDateTime,
// ...
)
class OffsetDateDeserializer(
private val formatter: DateTimeFormatter = DateTimeFormatter.ISO_DATE
) : JSR310DateTimeDeserializerBase<OffsetDateTime>(OffsetDateTime::class.java, formatter) {
override fun deserialize(parser: JsonParser, context: DeserializationContext): OffsetDateTime? {
if (parser.hasToken(JsonToken.VALUE_STRING)) {
val string = parser.text.trim()
if (string.isEmpty()) {
return null
}
val parsed: TemporalAccessor = formatter.parse(string)
val offset = if(parsed.isSupported(ChronoField.OFFSET_SECONDS)) ZoneOffset.from(parsed) else ZoneOffset.UTC
val localDate = LocalDate.from(parsed)
return OffsetDateTime.of(localDate.atStartOfDay(), offset)
}
throw context.wrongTokenException(parser, _valueClass, parser.currentToken, "date with offset must be contained in string")
}
override fun withDateFormat(otherFormatter: DateTimeFormatter?): JsonDeserializer<OffsetDateTime> = OffsetDateDeserializer(formatter)
}
As #JodaStephen explained in the comments, OffsetDate was not included in java.time to have a minimal set of classes. So, OffsetDateTime is the best option.
He also suggested to use DateTimeFormatterBuilder and parseDefaulting to create a DateTimeFormatter instance, to directly create OffsetDateTime from the formatters parsing result (TemporalAccessor). AFAIK, I still need to create a custom deserializer to use the formatter. Here is code, which solved my problem:
class OffsetDateDeserializer: JsonDeserializer<OffsetDateTime>() {
private val formatter = DateTimeFormatterBuilder()
.append(DateTimeFormatter.ISO_DATE)
.parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
.parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
.parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
.parseDefaulting(ChronoField.MILLI_OF_SECOND, 0)
.parseDefaulting(ChronoField.OFFSET_SECONDS, 0)
.toFormatter()
override fun deserialize(parser: JsonParser, context: DeserializationContext): OffsetDateTime? {
if (parser.hasToken(JsonToken.VALUE_STRING)) {
val string = parser.text.trim()
if (string.isEmpty()) {
return null
}
try {
return OffsetDateTime.from(formatter.parse(string))
} catch (e: DateTimeException){
throw context.wrongTokenException(parser, OffsetDateTime::class.java, parser.currentToken, "error while parsing date: ${e.message}")
}
}
throw context.wrongTokenException(parser, OffsetDateTime::class.java, parser.currentToken, "date with offset must be contained in string")
}
}