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+---
+title: Groovy - Using Enums
+tags:
+  - IT/Development/Groovy
+---
+
+Some examples (inspired by the Java Enum Tutorial):
+
+```groovy
+enum Day {
+    SUNDAY, MONDAY, TUESDAY, WEDNESDAY,
+    THURSDAY, FRIDAY, SATURDAY
+}
+
+def tellItLikeItIs(Day day) {
+    switch (day) {
+        case Day.MONDAY:
+            println "Mondays are bad."
+            break
+        case Day.FRIDAY:
+            println "Fridays are better."
+            break
+        case Day.SATURDAY:
+        case Day.SUNDAY:
+            println "Weekends are best."
+            break
+        default:
+            println "Midweek days are so-so."
+            break
+    }
+}
+
+tellItLikeItIs(Day.MONDAY)      // => Mondays are bad.
+tellItLikeItIs(Day.WEDNESDAY)   // => Midweek days are so-so.
+tellItLikeItIs(Day.FRIDAY)      // => Fridays are better.
+tellItLikeItIs(Day.SATURDAY)    // => Weekends are best.
+```
+
+Or with a bit of refactoring, you could write the switch like this:
+
+```groovy
+def today = Day.SATURDAY
+switch (today) {
+     // Saturday or Sunday
+     case [ Day.SATURDAY, Day.SUNDAY ]:
+         println "Weekends are cool"
+         break
+     // a day between Monday and Friday
+     case Day.MONDAY..Day.FRIDAY:
+         println "Boring work day"
+         break
+     default:
+         println "Are you sure this is a valid day?"
+}
+```
+
+Here is a coin example:
+
+```groovy
+enum Coin {
+    penny(1), nickel(5), dime(10), quarter(25)
+    Coin(int value) { this.value = value }
+    private final int value
+    public int value() { return value }
+}
+
+assert Coin.values().size() == 4
+
+def pocketMoney = 2 * Coin.quarter.value() + 5 * Coin.dime.value()
+assert pocketMoney == 100
+
+// another way to do abovedef coins = [ Coin.quarter ] * 2 + [ Coin.dime ] * 5
+println coins // => [ quarter, quarter, dime, dime, dime, dime, dime ]
+println coins.sum{ it.value() } // => 100
+```
+
+Here is a planet example:
+
+```groovy
+enum Planet {
+    MERCURY(3.303e+23, 2.4397e6),
+    VENUS(4.869e+24, 6.0518e6),
+    EARTH(5.976e+24, 6.37814e6),
+    MARS(6.421e+23, 3.3972e6),
+    JUPITER(1.9e+27, 7.1492e7),
+    SATURN(5.688e+26, 6.0268e7),
+    URANUS(8.686e+25, 2.5559e7),
+    NEPTUNE(1.024e+26, 2.4746e7)
+    private final double mass // in kilograms
+    private final double radius // in metres
+    Planet(double mass, double radius) {
+        this.mass = mass
+        this.radius = radius
+    }
+    private double mass() { return mass }
+    private double radius() { return radius }
+    // universal gravitational constant (m3 kg-1 s-2)
+    public static final double G = 6.67300E-11
+    double surfaceGravity() { return G * mass / (radius * radius) }
+    double surfaceWeight(double otherMass) { return otherMass * surfaceGravity() }
+}
+
+double earthWeight = 75.0 // kgdouble mass = earthWeight/Planet.EARTH.surfaceGravity()
+for (p in Planet.values()) {
+    printf("Your weight on %s is %f%n", p, p.surfaceWeight(mass))
+}
+
+// =>// Your weight on MERCURY is 28.331821// Your weight on VENUS is 67.874932// Your weight on EARTH is 75.000000// Your weight on MARS is 28.405289// Your weight on JUPITER is 189.791814// Your weight on SATURN is 79.951165// Your weight on URANUS is 67.884540// Your weight on NEPTUNE is 85.374605
+```
+
+Note: there are currently issues with using Groovy enums in conjunction with GroovyShell. Best bet would be to check Jira if you are having problems, e.g. http://jira.codehaus.org/browse/GROOVY-2135
+
+
+Evernote hilft dir, nichts zu vergessen und alles mühelos zu ordnen und zu organisieren. Evernote herunterladen.
+
+