[BAEL-19885] - Move articles out of core-kotlin part4
This commit is contained in:
catalin-burcea
@@ -1,23 +0,0 @@
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package com.baeldung.contract
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import kotlin.contracts.ExperimentalContracts
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import kotlin.contracts.InvocationKind
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import kotlin.contracts.contract
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@ExperimentalContracts
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inline fun <R> myRun(block: () -> R): R {
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contract {
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callsInPlace(block, InvocationKind.EXACTLY_ONCE)
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}
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return block()
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}
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@ExperimentalContracts
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fun callsInPlace() {
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val i: Int
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myRun {
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i = 1 // Without contract initialization is forbidden due to possible re-assignment
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}
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println(i) // Without contract variable might be uninitialized
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}
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@@ -1,43 +0,0 @@
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package com.baeldung.contract
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import kotlin.contracts.ExperimentalContracts
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import kotlin.contracts.contract
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data class Request(val arg: String)
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class Service {
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@ExperimentalContracts
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fun process(request: Request?) {
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validate(request)
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println(request.arg)
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}
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}
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@ExperimentalContracts
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private fun validate(request: Request?) {
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contract {
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returns() implies (request != null)
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}
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if (request == null) {
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throw IllegalArgumentException("Undefined request")
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}
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}
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data class MyEvent(val message: String)
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@ExperimentalContracts
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fun processEvent(event: Any?) {
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if (isInterested(event)) {
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println(event.message) // Compiler makes smart cast here with the help of contract
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}
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}
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@ExperimentalContracts
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fun isInterested(event: Any?): Boolean {
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contract {
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returns(true) implies (event is MyEvent)
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}
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return event is MyEvent
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}
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@@ -1,10 +0,0 @@
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package com.baeldung.datamapping
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data class User(
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val firstName: String,
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val lastName: String,
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val street: String,
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val houseNumber: String,
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val phone: String,
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val age: Int,
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val password: String)
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@@ -1,22 +0,0 @@
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package com.baeldung.datamapping
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import kotlin.reflect.full.memberProperties
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fun User.toUserView() = UserView(
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name = "$firstName $lastName",
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address = "$street $houseNumber",
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telephone = phone,
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age = age
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)
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fun User.toUserViewReflection() = with(::UserView) {
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val propertiesByName = User::class.memberProperties.associateBy { it.name }
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callBy(parameters.associate { parameter ->
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parameter to when (parameter.name) {
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UserView::name.name -> "$firstName $lastName"
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UserView::address.name -> "$street $houseNumber"
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UserView::telephone.name -> phone
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else -> propertiesByName[parameter.name]?.get(this@toUserViewReflection)
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}
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})
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}
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@@ -1,8 +0,0 @@
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package com.baeldung.datamapping
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data class UserView(
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val name: String,
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val address: String,
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val telephone: String,
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val age: Int
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)
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@@ -1,114 +0,0 @@
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package com.baeldung.kotlin.dsl
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abstract class Condition {
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fun and(initializer: Condition.() -> Unit) {
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addCondition(And().apply(initializer))
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}
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fun or(initializer: Condition.() -> Unit) {
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addCondition(Or().apply(initializer))
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}
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infix fun String.eq(value: Any?) {
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addCondition(Eq(this, value))
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}
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protected abstract fun addCondition(condition: Condition)
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}
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open class CompositeCondition(private val sqlOperator: String) : Condition() {
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private val conditions = mutableListOf<Condition>()
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override fun addCondition(condition: Condition) {
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conditions += condition
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}
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override fun toString(): String {
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return if (conditions.size == 1) {
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conditions.first().toString()
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} else {
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conditions.joinToString(prefix = "(", postfix = ")", separator = " $sqlOperator ") {
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"$it"
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}
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}
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}
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}
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class And : CompositeCondition("and")
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class Or : CompositeCondition("or")
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class Eq(private val column: String, private val value: Any?) : Condition() {
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init {
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if (value != null && value !is Number && value !is String) {
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throw IllegalArgumentException("Only <null>, numbers and strings values can be used in the 'where' clause")
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}
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}
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override fun addCondition(condition: Condition) {
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throw IllegalStateException("Can't add a nested condition to the sql 'eq'")
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}
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override fun toString(): String {
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return when (value) {
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null -> "$column is null"
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is String -> "$column = '$value'"
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else -> "$column = $value"
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}
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}
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}
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class SqlSelectBuilder {
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private val columns = mutableListOf<String>()
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private lateinit var table: String
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private var condition: Condition? = null
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fun select(vararg columns: String) {
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if (columns.isEmpty()) {
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throw IllegalArgumentException("At least one column should be defined")
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}
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if (this.columns.isNotEmpty()) {
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throw IllegalStateException("Detected an attempt to re-define columns to fetch. Current columns list: "
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+ "${this.columns}, new columns list: $columns")
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}
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this.columns.addAll(columns)
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}
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fun from(table: String) {
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this.table = table
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}
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fun where(initializer: Condition.() -> Unit) {
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condition = And().apply(initializer)
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}
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fun build(): String {
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if (!::table.isInitialized) {
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throw IllegalStateException("Failed to build an sql select - target table is undefined")
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}
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return toString()
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}
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override fun toString(): String {
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val columnsToFetch =
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if (columns.isEmpty()) {
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"*"
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} else {
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columns.joinToString(", ")
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}
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val conditionString =
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if (condition == null) {
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""
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} else {
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" where $condition"
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}
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return "select $columnsToFetch from $table$conditionString"
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}
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}
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fun query(initializer: SqlSelectBuilder.() -> Unit): SqlSelectBuilder {
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return SqlSelectBuilder().apply(initializer)
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}
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@@ -1,30 +0,0 @@
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package com.baeldung.kotlin.logging
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import org.slf4j.Logger
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open class LoggerAsExtensionOnAny {
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val logger = logger()
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fun log(s: String) {
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logger().info(s)
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logger.info(s)
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}
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}
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class ExtensionSubclass : LoggerAsExtensionOnAny()
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fun <T : Any> T.logger(): Logger = getLogger(getClassForLogging(javaClass))
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fun main(args: Array<String>) {
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LoggerAsExtensionOnAny().log("test")
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ExtensionSubclass().log("sub")
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"foo".logger().info("foo")
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1.logger().info("uh-oh!")
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SomeOtherClass().logger()
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}
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class SomeOtherClass {
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fun logger(): String {
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return "foo"
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}
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}
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-30
@@ -1,30 +0,0 @@
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package com.baeldung.kotlin.logging
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import org.slf4j.Logger
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import org.slf4j.LoggerFactory
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interface Logging
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inline fun <reified T : Logging> T.logger(): Logger =
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//Wrong logger name!
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//LoggerFactory.getLogger(javaClass.name + " w/interface")
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LoggerFactory.getLogger(getClassForLogging(T::class.java).name + " w/interface")
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open class LoggerAsExtensionOnMarkerInterface : Logging {
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companion object : Logging {
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val logger = logger()
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}
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fun log(s: String) {
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logger().info(s)
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logger.info(s)
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}
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}
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class MarkerExtensionSubclass : LoggerAsExtensionOnMarkerInterface()
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fun main(args: Array<String>) {
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LoggerAsExtensionOnMarkerInterface().log("test")
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MarkerExtensionSubclass().log("sub")
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"foo".logger().info("foo")
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}
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@@ -1,17 +0,0 @@
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package com.baeldung.kotlin.logging
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open class LoggerAsProperty {
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private val logger = getLogger(javaClass)
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fun log(s: String) {
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logger.info(s)
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}
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}
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class PropertySubclass : LoggerAsProperty()
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fun main(args: Array<String>) {
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LoggerAsProperty().log("test")
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PropertySubclass().log("sub")
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}
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@@ -1,47 +0,0 @@
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package com.baeldung.kotlin.logging
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import org.slf4j.Logger
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import kotlin.properties.ReadOnlyProperty
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import kotlin.reflect.KProperty
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open class LoggerAsPropertyDelegate {
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private val lazyLogger by lazyLogger()
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protected val logger by LoggerDelegate()
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private val logger2 = logger
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companion object {
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private val lazyLoggerComp by lazyLogger()
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private val loggerComp by LoggerDelegate()
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}
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open fun log(s: String) {
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logger.info(s)
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logger2.info(s)
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lazyLogger.info(s)
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loggerComp.info(s)
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lazyLoggerComp.info(s)
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}
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}
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class DelegateSubclass : LoggerAsPropertyDelegate() {
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override fun log(s: String) {
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logger.info("-- in sub")
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super.log(s)
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}
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}
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fun lazyLogger(forClass: Class<*>): Lazy<Logger> =
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lazy { getLogger(getClassForLogging(forClass)) }
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fun <T : Any> T.lazyLogger(): Lazy<Logger> = lazyLogger(javaClass)
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fun main(args: Array<String>) {
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LoggerAsPropertyDelegate().log("test")
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DelegateSubclass().log("sub")
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}
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class LoggerDelegate<in R : Any> : ReadOnlyProperty<R, Logger> {
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override fun getValue(thisRef: R, property: KProperty<*>) =
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getLogger(getClassForLogging(thisRef.javaClass))
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}
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@@ -1,44 +0,0 @@
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package com.baeldung.kotlin.logging
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open class LoggerInCompanionObject {
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companion object {
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private val loggerWithExplicitClass = getLogger(LoggerInCompanionObject::class.java)
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@Suppress("JAVA_CLASS_ON_COMPANION")
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private val loggerWithWrongClass = getLogger(javaClass)
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@Suppress("JAVA_CLASS_ON_COMPANION")
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private val logger = getLogger(javaClass.enclosingClass)
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}
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fun log(s: String) {
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loggerWithExplicitClass.info(s)
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loggerWithWrongClass.info(s)
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logger.info(s)
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}
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class Inner {
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companion object {
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private val loggerWithExplicitClass = getLogger(Inner::class.java)
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@Suppress("JAVA_CLASS_ON_COMPANION")
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@JvmStatic
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private val loggerWithWrongClass = getLogger(javaClass)
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@Suppress("JAVA_CLASS_ON_COMPANION")
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@JvmStatic
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private val logger = getLogger(javaClass.enclosingClass)
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}
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fun log(s: String) {
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loggerWithExplicitClass.info(s)
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loggerWithWrongClass.info(s)
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logger.info(s)
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}
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}
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}
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class CompanionSubclass : LoggerInCompanionObject()
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fun main(args: Array<String>) {
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LoggerInCompanionObject().log("test")
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LoggerInCompanionObject.Inner().log("test")
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CompanionSubclass().log("sub")
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}
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@@ -1,13 +0,0 @@
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package com.baeldung.kotlin.logging
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import org.slf4j.Logger
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import org.slf4j.LoggerFactory
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import kotlin.reflect.full.companionObject
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fun getLogger(forClass: Class<*>): Logger = LoggerFactory.getLogger(forClass)
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fun <T : Any> getClassForLogging(javaClass: Class<T>): Class<*> {
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return javaClass.enclosingClass?.takeIf {
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it.kotlin.companionObject?.java == javaClass
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} ?: javaClass
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}
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@@ -1,8 +0,0 @@
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package com.baeldung.thread
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class SimpleRunnable: Runnable {
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override fun run() {
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println("${Thread.currentThread()} has run.")
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}
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}
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@@ -1,8 +0,0 @@
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package com.baeldung.thread
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class SimpleThread: Thread() {
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override fun run() {
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println("${Thread.currentThread()} has run.")
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}
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}
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Reference in New Issue
Block a user