I need to get inputStream from ./resources but I got all the time NULL. Let me show you, what I did.
This is my simple code:
private const val CREDENTIALS_FILE_PATH = "/credentials.json"
val inputStream = javaClass.getResource(CREDENTIALS_FILE_PATH)
When I set debugger on inputStream, I got null all the time.
I tried write input in different way, but it also do not work.
val inputStream = this::class.java.classLoader.getResource(CREDENTIALS_FILE_PATH)
val inputStream = javaClass.classLoader.getResource(CREDENTIALS_FILE_PATH)
So I did something like that:
val inputStream = javaClass.getResource(".")
and I think there is problem, because this path refer to ./out/test/classes not to ./out/test/resources
Can I ask for some advice so that I can point to the file from ./resources?
Related
Trying to pass a data class User from one Activity to another using Intent.
My putExtra looks like this using my observe fun:
val intent = Intent(this, MainActivity::class.java)
intent.putExtra("userData",userData)
startActivity(intent)
My get routine looks like this:
userData = intent.getParcelableExtra<User>("userData") as User
or
userData = intent.getParcelableExtra("userData")
My problem is that Android Studio strikes out the function. My User data class is marked #Parcelize. It all ends up getParcelableExtra.
I've add to my gradle build:
id 'kotlin-parcelize'
I've read several posts about Parcelable being more modern than Serialable, so that's the technique I'm using. All the posts are from 2018 or prior and many of them in Java.
How does one send an data class from one Activity to another using Intent?
Since getParcelableExtra (String name) is deprecated from api level 33 you can use getParcelableExtra (String name, Class<T> clazz) from api level 33
In Your case use :
val userData =
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
intent.getParcelableExtra("userData", userData::class.java)
}
else{
intent.getParcelableExtra("userData") as userData?
}
where TIRAMISU is constant value 33
To get more info:Read this:
https://developer.android.com/reference/android/content/Intent#getParcelableExtra(java.lang.String,%20java.lang.Class%3CT%3E)
SOLUTION:
Given the need for compiler version 33 for the most modern solution, I went with a more backward compatible solution. This code translates the data object into a string, then back into the object.
SETUP: (PUT)
private var _userData = MutableLiveData<User>() // does the username and pw validate?
val userData : LiveData<User>
get() = _userData
SETUP: (GET)
private lateinit var userData: User
PUT CODE:
val intent = Intent(this, MainActivity::class.java)
val jsonUserData = Gson().toJson(userData)
intent.putExtra("userData",jsonUserData)
GET CODE:
val jsonUserData = intent.getStringExtra("userData")
userData = Gson().fromJson(jsonUserData, User::class.java)
I'm very new in kotlin and wanted to solve following problem with a do while:
I want to create a hash and want to check if there is the same hash stored in a key-value store as a key.
In java I would make it with a String variable which I declared outside the while. But that will only work with a var in Kotlin and I learned that it is common practise to avoid var.
My code looks as following (with var...)
var hash = ""
do {
hash = createHash(longUrl)
val optional = shortUrlRepository.findById(hash)
} while(optional.isPresent)
What would you say is the best way to solve this?
thank you a lot!
Maybe something like this?
val hash = generateSequence { createHash(longUrl) }
.first { !shortUrlRepository.findById(it).isPresent }
... and of course, you can always localize var and pass it outside as val.
val someVal = run {
var someVar: String = ""
// do super logic with var
someVar
}
...
I have an Annotation-processor, which should generate a class MyGeneratedClass containing a variable of another class MyEntity.
My code inside the processfunction:
val elementsWithAnnotation = roundEnv.getElementsAnnotatedWith(MyClass::class.java)
if (elementsWithAnnotation.isEmpty()) {
return true
}
val fileName = "MyGeneratedClass"
val packageName = "me.myname.sdk.generated"
val classBuilder = TypeSpec.classBuilder(fileName)
for (element in elementsWithAnnotation) {
val ann = element.getAnnotation(MyClass::class.java)
println("package: "+ ann.javaClass.packageName)
val variableBuilder =
PropertySpec.varBuilder(
name = element.simpleName.toString(),
type = ClassName("", element.asType().asTypeName().asNullable().toString()),
).initializer("null")
classBuilder
.addProperty(variableBuilder.build())
}
val file = FileSpec.builder(packageName, fileName)
.addType(classBuilder.build())
.build()
val generatedDirectory = processingEnv.options[KAPT_KOTLIN_GENERATED_OPTION_NAME]
file.writeTo(File(generatedDirectory, "$fileName.kt"))
return true
But the generated code misses the import MyEntity
package me.myname.sdk.generated
class MyGeneratedClass {
var MyEntity: MyEntity? = null
}
When looking inside the generated file, IntelliJ suggests me to import MyEntity, which resolves the error. But how can I achieve, that the import MyEntity statement is being added when generating the file?
looking at the kotlinpoet documentation https://square.github.io/kotlinpoet/1.x/kotlinpoet/kotlinpoet/com.squareup.kotlinpoet/-class-name/index.html
seems like the first argument in your code, which is a empty string is the package name you are missing in the generated code.
in my experience kotlinpoet is much happier to generate code that in in packages. it sometimes does silly things with types in the root/default package.
I have read a lot of questions and answers, but are not really satisfied and successful
My Problem: write with Kotlin to a sdcard to a specific directory
Working is
var filenamex = "export.csv"
var patt = getExternalFilesDirs(null)
var path = patt[1]
//create fileOut object
var fileOut = File(path, filenamex)
//create a new file
fileOut.createNewFile()
with getExternalFIlesDirs() I get the external storage and the sdcard. With path = patt[1] i get the adress of my sd-card.
this is
"/storage/105E-XXXX/Android/data/com.example.myApp/files"
This works to write data in this directory.
But I would like to write into an other directory, for example
"/sdcard/myApp"
A lot of examples say, this should work, bit it does not.
So I tried to take
"/storage/105E-XXXX/myApp"
Why doesn't it work? Ist the same beginning of storage /storage/105E-XXXX/, so it is MY sd-card.?
As I mentioned, it works on the sd-card, so it is not a problem of write-permission to the sdcard?
Any idea?
(I also failed with FileOutputStream and other things)
Try Out this..
var filenamex = "export.csv"
var path = getExternalStorageDirectory() + "//your desired folder"
var fileOut = File(path, filenamex)
fileOut.createNewFile()
first, I create empty Array(Kotlin) instance in companion object.
companion object {
var strarray: Array<String> = arrayOf()
var objectarray: LinkedHashMap<Int, List<Any>> = LinkedHashMap<Int, List<Any>>()
}
and I expected that I use empty array instance when read textString from CSV File.
fun csvFileToString():String {
val inputStream = File(Paths.get("").toAbsolutePath().toString()
.plus("/src/main/SampleCSVFile_2kb.csv")).inputStream()
val reader = inputStream.bufferedReader()
var iterator = reader.lineSequence().iterator()
var index:Int = 1;
while (iterator.hasNext()){
var lineText:String = iterator.next()
strarray.set(index, lineText)
index++
}
return ""
}
but when I run that source code
a.csvFileToString()
println(CsvParser.strarray)
occured exception
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
strarray.set(index, lineText) <<<<<<<<< because of this line
can I use Array(from kotlin collection) like ArrayList(from java collection)?
You can add a new item to an array using +=, for example: item += item
private var songs: Array<String> = arrayOf()
fun add(input: String) {
songs += input
}
Size of Array is defined at its creation and cannot be modified - in your example it equals 0.
If you want to create Array with dynamic size you should use ArrayList.
arrayOf gives you an array. Arrays have fixed length even in Java.
listOf gives you an immutable list. You cannot add or remove items in this list.
What you're looking for is mutableListOf<String>.
In your current approach, reusing a member property, don't forget to clear the list before every use.
Your code can be further simplified (and improved) like so:
out.clear()
inputStream.bufferedReader().use { reader -> // Use takes care of closing reader.
val lines = reader.lineSequence()
out.addAll(lines) // MutableList can add all from sequence.
}
Now imagine you wanted to consume the output list but needed to parse another file at the same time.
Consider working towards a pure function (no side effects, for now no accessing member properties) and simplifying it even further:
fun csvFileToString(): String { // Now method returns something useful.
val inputStream = File(Paths.get("").toAbsolutePath().toString()
.plus("/src/main/SampleCSVFile_2kb.csv")).inputStream()
inputStream.bufferedReader().use {
return it.lineSequence().joinToString("\n")
}
}
In this case we can totally skip the lists and arrays and just read the text:
inputStream.bufferedReader().use {
return it.readText()
}
I'm assuming that's what you wanted in the first place.
Kotlin has a lot of useful extension functions built-in. Look for them first.