I am trying a sample with Room Persistence Library. I created an Entity: @Entity public class Agent { @PrimaryKey public String guid; public String name; public String email; public String password; public String phone; public String licence; } Created a DAO class: @Dao public interface AgentDao { @Query(“SELECT COUNT(*) FROM Agent where email = :email … Read more
In Java 8, there is Stream.collect which allows aggregations on collections. In Kotlin, this does not exist in the same way, other than maybe as a collection of extension functions in the stdlib. But it isn’t clear what the equivalences are for different use cases. For example, at the top of the JavaDoc for Collectors … Read more
Kotlin has very nice iterating functions, like forEach or repeat, but I am not able to make the break and continue operators work with them (both local and non-local): repeat(5) { break } (1..5).forEach { continue@forEach } The goal is to mimic usual loops with the functional syntax as close as it might be. It … Read more
What is the correct way to define a var in kotlin that has a public getter and private (only internally modifiable) setter? 2 Answers 2
I’ve got a gradle FAILURE: …”Deprecated Gradle features were used in this build, making it incompatible with Gradle 5.0.” Case description: Attached to the project codebase the next libs: APP/build.gradle //(Required) Writing and executing Unit Tests on the JUnit Platform testImplementation “org.junit.jupiter:junit-jupiter-api:5.2.0” testRuntimeOnly “org.junit.jupiter:junit-jupiter-engine:5.2.0” // (Optional) If you need “Parameterized Tests” testImplementation “org.junit.jupiter:junit-jupiter-params:5.2.0” // (Optional) … Read more
I am having an issue with the new Android Navigation Architecture component when I try to navigate from one Fragment to another, I get this weird error: java.lang.IllegalArgumentException: navigation destination XXX is unknown to this NavController Every other navigation works fine except this particular one. I use findNavController() function of Fragment to get access to … Read more
For example I have a list of strings like: val list = listOf(“a”, “b”, “c”, “d”) and I want to convert it to a map, where the strings are the keys. I know I should use the .toMap() function, but I don’t know how, and I haven’t seen any examples of it. 6 Answers 6
Is it possible to access extension functions from Java code? I defined the extension function in a Kotlin file. package com.test.extensions import com.test.model.MyModel /** * */ public fun MyModel.bar(): Int { return this.name.length() } Where MyModel is a (generated) java class. Now, I wanted to access it in my normal java code: MyModel model = … Read more
I’m reading Kotlin Coroutine and know that it is based on suspend function. But what does suspend mean? Coroutine or function gets suspended? From https://kotlinlang.org/docs/reference/coroutines.html Basically, coroutines are computations that can be suspended without blocking a thread I heard people often say “suspend function”. But I think it is the coroutine who gets suspended because … Read more
I see that Kotlin has ByteArray, ShortArray, IntArray, CharArray, DoubleArray, FloatArray, which are equivalent to byte[], short[], int[],char[], double[], float[] in Java. Now I’m wondering, is there any StringArray equivalent to Java’s String[]? 8 Answers 8
