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-rw-r--r--java.html.markdown66
1 files changed, 62 insertions, 4 deletions
diff --git a/java.html.markdown b/java.html.markdown
index aae64ccf..1813f81c 100644
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+++ b/java.html.markdown
@@ -186,9 +186,9 @@ public class LearnJava {
// operations perform as could be expected for a
// doubly-linked list.
// Maps - A set of objects that map keys to values. Map is
- // an interface and therefore cannot be instantiated.
- // The type of keys and values contained in a Map must
- // be specified upon instantiation of the implementing
+ // an interface and therefore cannot be instantiated.
+ // The type of keys and values contained in a Map must
+ // be specified upon instantiation of the implementing
// class. Each key may map to only one corresponding value,
// and each key may appear only once (no duplicates).
// HashMaps - This class uses a hashtable to implement the Map
@@ -697,6 +697,64 @@ public abstract class Mammal()
return true;
}
}
+
+
+// Enum Type
+//
+// An enum type is a special data type that enables for a variable to be a set of predefined constants. The // variable must be equal to one of the values that have been predefined for it.
+// Because they are constants, the names of an enum type's fields are in uppercase letters.
+// In the Java programming language, you define an enum type by using the enum keyword. For example, you would
+// specify a days-of-the-week enum type as:
+
+public enum Day {
+ SUNDAY, MONDAY, TUESDAY, WEDNESDAY,
+ THURSDAY, FRIDAY, SATURDAY
+}
+
+// We can use our enum Day like that:
+
+public class EnumTest {
+
+ // Variable Enum
+ Day day;
+
+ public EnumTest(Day day) {
+ this.day = day;
+ }
+
+ public void tellItLikeItIs() {
+ switch (day) {
+ case MONDAY:
+ System.out.println("Mondays are bad.");
+ break;
+
+ case FRIDAY:
+ System.out.println("Fridays are better.");
+ break;
+
+ case SATURDAY:
+ case SUNDAY:
+ System.out.println("Weekends are best.");
+ break;
+
+ default:
+ System.out.println("Midweek days are so-so.");
+ break;
+ }
+ }
+
+ public static void main(String[] args) {
+ EnumTest firstDay = new EnumTest(Day.MONDAY);
+ firstDay.tellItLikeItIs(); // => Mondays are bad.
+ EnumTest thirdDay = new EnumTest(Day.WEDNESDAY);
+ thirdDay.tellItLikeItIs(); // => Midweek days are so-so.
+ }
+}
+
+// Enum types are much more powerful than we show above.
+// The enum body can include methods and other fields.
+// You can se more at https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html
+
```
## Further Reading
@@ -720,7 +778,7 @@ The links provided here below are just to get an understanding of the topic, fee
* [Generics](http://docs.oracle.com/javase/tutorial/java/generics/index.html)
-* [Java Code Conventions](http://www.oracle.com/technetwork/java/codeconv-138413.html)
+* [Java Code Conventions](http://www.oracle.com/technetwork/java/codeconvtoc-136057.html)
**Online Practice and Tutorials**