KTLN-378 log4j Kotlin

Author: thebaubau

kotlin-logging/pom.xml

@@ -21,6 +21,17 @@
             <artifactId>kotlin-logging-jvm</artifactId>
             <version>${kotlin-logging-jvm.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-core</artifactId>
+            <version>2.20.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-api-kotlin</artifactId>
+            <version>1.5.0</version>
+        </dependency>
+
     </dependencies>
 
     <properties>

kotlin-logging/src/main/kotlin/com/baeldung/log4j/Enemy.kt

@@ -0,0 +1,9 @@
+package com.baeldung.log4j
+
+import org.apache.logging.log4j.kotlin.logger
+
+class Enemy {
+    fun shoot() {
+        logger.warn { "Enemy shoots the player" }
+    }
+}

kotlin-logging/src/main/kotlin/com/baeldung/log4j/Game.kt

@@ -0,0 +1,25 @@
+import org.apache.logging.log4j.kotlin.logger
+
+class Game {
+    companion object {
+        private val logger = logger()
+    }
+
+    fun startGame() {
+        logger.info { "Game is starting..." }
+    }
+
+    fun loadLevel(levelName: String) {
+        logger.info { "Loading level: $levelName" }
+        try {
+            if (levelName.isBlank()) {
+                throw IllegalArgumentException("Level name cannot be empty")
+            }
+            logger.debug { "Level '$levelName' loaded successfully." }
+        } catch (ex: Exception) {
+            logger.error(ex) { "Error loading level: $levelName" }
+        }
+    }
+}
+
+//class Game { private val logger = logger() fun startGame() { logger.info { "Game is starting..." } } }

kotlin-logging/src/main/kotlin/com/baeldung/log4j/GameUtil.kt

@@ -0,0 +1,9 @@
+package com.baeldung.log4j
+
+import org.apache.logging.log4j.kotlin.Logging
+
+class GameUtil : Logging {
+    fun logEvent(event: String) {
+        logger.info { "Game Event: $event" }
+    }
+}

kotlin-logging/src/main/kotlin/com/baeldung/log4j/Log4jMain.kt

@@ -0,0 +1,20 @@
+package com.baeldung.log4j
+
+import Game
+
+fun main() {
+    val game = Game()
+    val player = Player("Baeldung")
+    val enemy = Enemy()
+
+    game.startGame()
+    game.loadLevel("Level 1")
+
+    player.joinGame()
+    enemy.shoot()
+
+    player.takeDamage(100)
+    GameUtil().logEvent("Player died")
+
+    game.loadLevel("")
+}

kotlin-logging/src/main/kotlin/com/baeldung/log4j/Player.kt

@@ -0,0 +1,15 @@
+package com.baeldung.log4j
+
+import org.apache.logging.log4j.kotlin.logger
+
+class Player(val name: String) {
+    private val logger = logger("Player Action")
+
+    fun joinGame() {
+        logger.info { "Player '$name' has joined the game." }
+    }
+
+    fun takeDamage(amount: Int) {
+        logger.warn { "Player '$name' took $amount damage!" }
+    }
+}

kotlin-logging/src/main/resources/log4j2.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="WARN">
+    <Appenders>
+        <Console name="ConsoleAppender" target="SYSTEM_OUT">
+            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
+        </Console>
+    </Appenders>
+    <Loggers>
+        <Root level="debug">
+            <AppenderRef ref="ConsoleAppender"/>
+        </Root>
+    </Loggers>
+</Configuration>