Add samples for Random.nextX() functions

2020-10-07 15:48:55 -05:00
parent ebdd023633
commit 173954b3b3
2 changed files with 133 additions and 1 deletions
@@ -6,6 +6,7 @@
 package samples.random

 import samples.*
+import kotlin.math.sin
 import kotlin.random.Random
 import kotlin.test.assertTrue

@@ -38,4 +39,105 @@ class Randoms {
        // random with another seed produce another sequence
        assertPrints(randomValues3, "[14, 48, 57, 67, 82, 7, 61, 27, 14, 59]")
    }
-}
+
+    @Sample
+    fun nextBits() {
+        // always generates a 0
+        println(Random.nextBits(0))
+        // randomly generates a 0 or 1
+        println(Random.nextBits(1))
+        // generates a random non-negative Int value less than 256
+        println(Random.nextBits(8))
+        // generates a random Int value, may generate a negative value as well
+        println(Random.nextBits(32))
+    }
+
+    @Sample
+    fun nextBoolean() {
+        val presents = listOf("Candy", "Balloon", "Ball")
+        // a random partition, the result may be different every time
+        val (alicePresents, bobPresents) = presents.partition { Random.nextBoolean() }
+
+        println("Alice receives $alicePresents")
+        println("Bob receives $bobPresents")
+    }
+
+    @Sample
+    fun nextBytes() {
+        val bytes = ByteArray(4)
+        assertPrints(bytes.contentToString(), "[0, 0, 0, 0]")
+
+        Random.nextBytes(bytes, 1, 3)
+        // second and third bytes are generated, rest unchanged
+        println(bytes.contentToString())
+
+        Random.nextBytes(bytes)
+        // all bytes are newly generated
+        println(bytes.contentToString())
+
+        val newBytes = Random.nextBytes(5)
+        // a new byte array filled with random values
+        println(newBytes.contentToString())
+    }
+
+    @Sample
+    fun nextDouble() {
+        if (Random.nextDouble() <= 0.3) {
+            println("There was 30% possibility of rainy weather today and it is raining.")
+        } else {
+            println("There was 70% possibility of sunny weather today and the sun is shining.")
+        }
+    }
+
+    @Sample
+    fun nextDoubleFromUntil() {
+        val firstAngle = Random.nextDouble(until = Math.PI / 6);
+        assertTrue(sin(firstAngle) < 0.5)
+
+        val secondAngle = Random.nextDouble(from = Math.PI / 6, until = Math.PI / 2)
+        val sinValue = sin(secondAngle)
+        assertTrue(sinValue >= 0.5 && sinValue < 1.0)
+    }
+
+    @Sample
+    fun nextFloat() {
+        if (Random.nextFloat() <= 0.3) {
+            println("There was 30% possibility of rainy weather today and it is raining.")
+        } else {
+            println("There was 70% possibility of sunny weather today and the sun is shining.")
+        }
+    }
+
+    @Sample
+    fun nextInt() {
+        val randomInts = List(5) { Random.nextInt() }
+        println(randomInts)
+        val sortedRandomInts = randomInts.sorted()
+        println(sortedRandomInts)
+    }
+
+    @Sample
+    fun nextIntFromUntil() {
+        val menu = listOf("Omelette", "Porridge", "Cereal", "Chicken", "Pizza", "Pasta")
+        val forBreakfast = Random.nextInt(until = 3).let { menu[it] }
+        val forLunch = Random.nextInt(from = 3, until = 6).let { menu[it] }
+        // new meals every time
+        println("Today I want $forBreakfast for breakfast, and $forLunch for lunch.")
+    }
+
+    @Sample
+    fun nextLong() {
+        val randomLongs = List(5) { Random.nextLong() }
+        println(randomLongs)
+        val sortedRandomLongs = randomLongs.sorted()
+        println(sortedRandomLongs)
+    }
+
+    @Sample
+    fun nextLongFromUntil() {
+        val fileSize = Random.nextLong(until = 1_099_511_627_776)
+        println("A file of $fileSize bytes fits on a 1TB storage.")
+        val long = Random.nextLong(Int.MAX_VALUE + 1L, Long.MAX_VALUE)
+        println("Number $long doesn't fit in an Int.")
+    }
+}