I am generating a class using kotlinpoet and one of the method to be generated is available to me as string (full function definition), how will I add that to a TypeSpec?
// if I have function definition like this
val funDefinition = "fun myFun(){}"
// I don't want to generate like following
TypeSpec.classBuilder("myClass").addFunction(FunSpec.builder("myFun").build())
// I could not see an option like following
TypeSpec.classBuilder("myClass").aMethodToAddFunctionFromString(funDefinition)
Is this possible with kotlinpoet or with some other library?
Related
I am using annotations and reflection to create a parser for some custom made files used in the project I work with
I have this annotation that will be used to annotate most data class constructor parameters
annotation class Element(val name: String = "",val type: ElementType = ElementType.Value)
the enum ElementType has these values
enum class XElementType {
Value,
Attribute,
Ignore
}
is there a way to create a shorthand or alternate so that instead of using
#Element(type=ElementType.Ignore)
val ignoredVariable:String
I can use something like
#IgnoreElement
val ignoredVariable:String
which will resolve to Element("",ElementType.Ignore) ?
Trying to figure out how to pass some parameters to my custom implementation of TestWatcher in Junit5. The base class for all tests is set to #ExtendWith with the TestWatcher. Trying to keep it as simple as possible and I can't seem to find a straightforward answer on how to do this
I was struggling on a similar problem, basically I needed a global parameter (a separator string data) for the annotation #DisplayNameGenerator().
Because the lack of code examples of how you're trying to resolve this I'm gonna explain my approach of how to get a parameter provided by the user and see if it works for you,
I created a interface with the return of the String value that is my custom parameter that I wanted to get from the user,
#Target(ElementType.TYPE)
#Retention(RetentionPolicy.RUNTIME)
#Inherited
#API(status = EXPERIMENTAL, since = "5.4")
public #interface IndicativeSentencesSeparator {
String value();
}
So this way I could create my test with this new interface, and passing the parameter but also making it optional to use, like this,
#DisplayName("My Test")
#DisplayNameGeneration(DisplayNameGenerator.IndicativeSentencesGenerator.class)
#IndicativeSentencesSeparator(" --> ")
class MyTestClass { //Some test methods and stuff }
To get the this new class in the implementation, I used the java method class.getAnnotation(classType) in the class that you're trying to extract the value, sending by parameter the class to find, in this case the interface I created.
IndicativeSentencesSeparator separator =
myTestClass.getAnnotation(IndicativeSentencesSeparator.class);
And finally to get the parameter used the getter value,
String parameter = separator.value();
Is it possible to create extension of final classes like String? Like in swift it is possible to add additional methods inside a extension of final class.
For an example - I would like to create a method in String extension which will tell me String have valid length for password.
val password : String = mEdtPassword!!.getText().toString()
// how to define haveValidLength method in extension
val isValid : Boolean = password.haveValidLength()
Note - That example is just for a sake to understand usability of extension, not a real scenario.
yes, you can. Kotin extension method provides the ability to extend a class with new functionality without having to inherit from the class or use any type of design pattern such as Decorator.
Below is an extension method for a String:
// v--- the extension method receiver type
fun String.at(value: Int) = this[value]
And the extension method code generated as Java below:
public static char at(String receiver, int value){
return receiver.charAt(value);
}
So an extension method in Kotlin is using delegation rather than inheritance.
Then you can calling an extension method like as its member function as below:
println("bar".at(1))//println 'a'
You also can write an extension method for the existing extension function, for example:
fun String.substring(value: Int): String = TODO()
// v--- throws exception rather than return "ar"
"bar".substring(1)
But you can't write an extension method for the existing member function, for example:
operator fun String.get(value: Int): Char = TODO()
// v--- return 'a' rather than throws an Exception
val second = "bar"[1]
Trying to add more detail, this answer might be helpful for someone.
Yes we can add additional methods to final classes like String. For an example I would like to add one method in String which will tell me that my String have valid number of characters for password or not.
So what I have to do is, I have ti create a below function which can be written in same class or at different separate class file.
fun String.hasValidPassword() : Boolean {
// Even no need to send string from outside, use 'this' for reference of a String
return !TextUtils.isEmpty(this) && this.length > 6
}
And now from anywhere call
val isValid : Boolean = password.haveValidLength()
Suggestion
If your application just has a single password validation, then there is no problem.
However, I don't suggest you write such a extension method hasValidPassword if the application has more than one validation. since the extension method is satically, you can't change your hasValidPassword in runtime. So if you want to change the validation in runtime, you should using a function instead, for example:
class PasswordRepository(private val validate:(String)->Boolean){
fun save(value:String){
if(validate(value)){
//TODO persist the password
}
}
}
val permitAll = PasswordRepository {true}
val denyAll = PasswordRepository {false}
permitAll.save("it will be persisted")
denyAll.save("it will not be persisted")
In other words, the extension method above violates Single Responsibility Principle, it does validation & string operations.
You can do that with extension functions in Kotlin. With extensions, you are able to add extra functionality to a class that you do or do not have access to; for example a legacy code base. In the example given in the Kotlin docs here, swap was added to MutableList<Int> which doesn't have swap originally. A this keyword is used that refers to the object that the swap functionality will operate on. In the example below, this refers to testList
val testList = mutableListOf(1, 2, 3)
testList.swap(0, 2)
class A{
int x = 10;
}
This is A.java
I want to get NewA.java
class NewA{
int x = 10;
Sting text = "B";
}
I want to add a variable using javaparser.
You need to do this:
Parse the code
Find the point where you want to add your element
Add the element you want
Dump back the code
The first point is trivial, just use the JavaParser.parse method. You will get a CompilationUnit. In the example you shown you are adding a field in a class declaration, so you need first to get that class declaration. Call getTypes and look into that list for the declaration you want or just call getClassByName.
Once you have your class declaration you can call addMember on it. In your example you are adding a field so you need to instantiate a FieldDeclaration.
Once you are done you take your CompilationUnit and call toString. You will get back the modified source code.
Source: I am a JavaParser committer
Is there a way to use Parceler with Kotlin data classes and constructor for serialization without using #ParcelProperty annotation for each field?
If I try and use library like this:
#Parcel
data class Valve #ParcelConstructor constructor(val size: Int)
I get Error:Parceler: No corresponding property found for constructor parameter arg0. But if I add #ParcelProperty("size") it works just fine.
Why is that?
Update:
There are other another way to use this library.
I could just remove #ParcelConstructor annotation, but then I will get error
Error:Parceler: No #ParcelConstructor annotated constructor and no default empty bean constructor found.
I think (haven't tested it) I also could make all constructor parameters optional and add #JvmOverloads but that has a side effect that I have to check all properties of the class if they are null or not.
Update 2:
This is what worked for me:
#Parcel
data class Valve(val size: Int? = null)
In short generated Java class must have default empty constructor. One way to achieve that is to do as above - all variables should have default values.
According to the docs, Parceler by default works with public fields. But a usual Kotlin data class (as in your example) is rather a "traditional getter/setter bean", since every Kotlin property is represented by a private field and a getter/[setter].
TL; DR: I think this will work:
#Parcel(Serialization.BEAN)
data class Valve(val size: Int = 10)
Note the default value, it allows Kotlin to automatically generate an additional empty constructor, which is required by the Java Been specification.
Another way would be to mark the constructor that we already have:
#Parcel(Serialization.BEAN)
data class Driver #ParcelConstructor constructor(val name: String)
The specific document: https://github.com/johncarl81/parceler#gettersetter-serialization
I know this question already has an answer, but for future viewers who are also struggling to get Parceler to work with kotlin data objects, I wrote a new annotation processor to generate the Parcelable boilerplate for Kotlin data classes. It's designed to massively reduce the boilerplate code in making your data classes Parcelable:
https://github.com/grandstaish/paperparcel
Usage:
Annotate your data class with #PaperParcel, implement PaperParcelable, and add a JVM static instance of the generated CREATOR e.g.:
#PaperParcel
data class Example(
val test: Int,
...
) : PaperParcelable {
companion object {
#JvmField val CREATOR = PaperParcelExample.CREATOR
}
}
Now your data class is Parcelable and can be passed directly to a Bundle or Intent
Edit: Update with latest API
Just add the default constructor:
#Parcel
data class Valve(val size: Int) {
constructor() : this(0)
}
if you use Kotlin 1.1.4 or above it's easier to use #Parcelize annotation
For doing this first add this to build.gradle
android {
//other codes
//for using latest experimental build of Android Extensions
androidExtensions {
experimental = true
}
}
Then change your class like this
#Parcelize
data class Valve(val size: Int? = null) : Parcelable