Stage4: Convert length and weight values in a loop

src/unitConverter/Unit.kt

@@ -0,0 +1,9 @@
+package unitConverter
+
+class Unit(
+    val type: UnitTypes,
+    val acronym: String,
+    val single: String,
+    val multiple: String,
+    val factor: Double
+)

src/unitConverter/UnitTypes.kt

@@ -0,0 +1,6 @@
+package unitConverter
+
+enum class UnitTypes {
+    LENGTH,
+    WEIGHT
+}

src/unitConverter/main.kt

@@ -1,5 +1,79 @@
 package unitConverter
 
+import java.util.*
+
 fun main(args: Array<String>) {
-    print("Hello world!")
+    val unitsMap = initUnitsMap()
+    while (true) {
+        val (value, initialUnit, finalUnit, exitFlag) = readData(unitsMap)
+        if (exitFlag) {
+            break
+        }
+        if (value >= 0 && isPossibleToConvert(initialUnit!!, finalUnit!!)) {
+            val correctInitialUnit = if (value == 1.0) initialUnit.single else initialUnit.multiple
+            val result = value * initialUnit.factor / finalUnit.factor
+            val correctMetersUnit = if (result == 1.0) finalUnit.single else finalUnit.multiple
+            println("$value $correctInitialUnit is $result $correctMetersUnit")
+        }
+    }
+}
+
+private fun isPossibleToConvert(firstUnit: Unit, secondUnit: Unit): Boolean = firstUnit.type == secondUnit.type
+
+data class Result(val result: Double, val initUnit: Unit?, val finalUnit: Unit?, var exitFlag: Boolean)
+
+private fun readData(unitsMap: Map<String, Unit>): Result {
+    println("Enter what you want to convert (or Exit):")
+    val scanner = Scanner(System.`in`)
+    var result = Result(-1.0, null, null, false)
+    val next = scanner.next().toLowerCase()
+    if (next == "exit") {
+        result.exitFlag = true
+    } else {
+        val value = next.toDouble()
+        val initialUnit = findUnit(scanner.next().toLowerCase(), unitsMap)
+        scanner.next()
+        val finalUnit = findUnit(scanner.next().toLowerCase(), unitsMap)
+        if (value >= 0 && initialUnit != null && finalUnit != null) {
+            result = Result(value, initialUnit, finalUnit, false)
+        }
+    }
+    return result
+}
+
+private fun findUnit(string: String, unitsMap: Map<String, Unit>): Unit? {
+    return when (string) {
+        "m", "meter", "meters" -> unitsMap["m"]
+        "km", "kilometer", "kilometers" -> unitsMap["km"]
+        "cm", "centimeter", "centimeters" -> unitsMap["cm"]
+        "mm", "millimeter", "millimeters" -> unitsMap["mm"]
+        "mi", "mile", "miles" -> unitsMap["mi"]
+        "yd", "yard", "yards" -> unitsMap["yd"]
+        "ft", "foot", "feet" -> unitsMap["ft"]
+        "in", "inch", "inches" -> unitsMap["in"]
+        "g", "gram", "grams" -> unitsMap["g"]
+        "kg", "kilogram", "kilograms" -> unitsMap["kg"]
+        "mg", "milligram", "milligrams" -> unitsMap["mg"]
+        "lb", "pound", "pounds" -> unitsMap["lb"]
+        "oz", "ounce", "ounces" -> unitsMap["oz"]
+        else -> null
+    }
+}
+
+private fun initUnitsMap(): Map<String, Unit> {
+    return mapOf(
+        "m" to Unit(UnitTypes.LENGTH, "m", "meter", "meters", 1.0),
+        "km" to Unit(UnitTypes.LENGTH, "km", "kilometer", "kilometers", 1000.0),
+        "cm" to Unit(UnitTypes.LENGTH, "cm", "centimeter", "centimeters", 0.01),
+        "mm" to Unit(UnitTypes.LENGTH, "mm", "millimeter", "millimeters", 0.001),
+        "mi" to Unit(UnitTypes.LENGTH, "mi", "mile", "miles", 1609.35),
+        "yd" to Unit(UnitTypes.LENGTH, "yd", "yard", "yards", 0.9144),
+        "ft" to Unit(UnitTypes.LENGTH, "ft", "foot", "feet", 0.3048),
+        "in" to Unit(UnitTypes.LENGTH, "in", "inch", "inches", 0.0254),
+        "g" to Unit(UnitTypes.WEIGHT, "g", "gram", "grams", 1.0),
+        "kg" to Unit(UnitTypes.WEIGHT, "kg", "kilogram", "kilograms", 1000.0),
+        "mg" to Unit(UnitTypes.WEIGHT, "mg", "milligram", "milligrams", 0.001),
+        "lb" to Unit(UnitTypes.WEIGHT, "lb", "pound", "pounds", 453.592),
+        "oz" to Unit(UnitTypes.WEIGHT, "oz", "ounce", "ounces", 28.3495)
+    )
 }