Merge pull request #846 from hangga/repeat-task

KTLN-435 - Scheduling Repeating Task in Kotlin

Author: theangrydev

core-kotlin-modules/core-kotlin-concurrency-3/src/main/java/com/baeldung/schedulingrepeatingtask/UsingScheduledThreadPool.kt

@@ -0,0 +1,11 @@
+package com.baeldung.schedulingrepeatingtask
+
+import java.util.concurrent.Executors
+import java.util.concurrent.TimeUnit
+
+fun main(){
+    val scheduler = Executors.newScheduledThreadPool(1)
+    scheduler.scheduleAtFixedRate({
+        println("Complex task completed!")
+    }, 0, 1, TimeUnit.SECONDS)
+}

core-kotlin-modules/core-kotlin-concurrency-3/src/main/java/com/baeldung/schedulingrepeatingtask/UsingTimer.kt

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+package com.baeldung.schedulingrepeatingtask
+
+import java.util.Timer
+import kotlin.concurrent.schedule
+
+fun main(){
+    val timer = Timer()
+    timer.schedule(0, 1000) {
+        println("Timer ticked!")
+    }
+}

core-kotlin-modules/core-kotlin-concurrency-3/src/test/java/com/baeldung/schedulingrepeatingtask/SchedulingRepeatingTaskUnitTest.kt

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+package com.baeldung.schedulingrepeatingtask
+
+import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.take
+import kotlinx.coroutines.flow.transform
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.seconds
+
+class SchedulingRepeatingTaskUnitTest {
+
+    @Test
+    fun `using repeat and delay`() = runBlocking {
+        var count = 0
+        repeat(10) {
+            count++
+            println("Timer ticked! $count")
+            delay(1000.milliseconds)
+        }
+
+        assertEquals(10, count)
+    }
+
+    @Test
+    fun `using withTimeout`(): Unit = runBlocking {
+        var count = 0
+        assertThrows<TimeoutCancellationException> {
+            withTimeout(5000.milliseconds) {
+                while (true) {
+                    count++
+                    println("Waiting for timeout")
+                    delay(1000.milliseconds)
+                }
+            }
+        }
+        assertEquals(5, count)
+    }
+
+    @Test
+    fun `using flow collect take`() = runBlocking {
+
+        val flow = flow {
+            while (true) {
+                emit(Unit)
+                delay(1000.milliseconds)
+            }
+        }
+
+        var count = 0
+
+        flow.take(10).collect{
+            count++
+            println(count)
+        }
+
+        assertEquals(10, count)
+    }
+
+}