From 50a0bbf33f19ea33c38f4b025c771e57bdfe937b Mon Sep 17 00:00:00 2001 From: Raphael Nascimento Date: Wed, 14 Oct 2015 22:12:06 -0300 Subject: [java/en] Enum Type Short overview about enum type. --- java.html.markdown | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) diff --git a/java.html.markdown b/java.html.markdown index 35ec57d8..bc119eb1 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -7,6 +7,7 @@ contributors: - ["Simon Morgan", "http://sjm.io/"] - ["Zachary Ferguson", "http://github.com/zfergus2"] - ["Cameron Schermerhorn", "http://github.com/cschermerhorn"] + - ["Raphael Nascimento", "http://github.com/raphaelbn"] filename: LearnJava.java --- @@ -670,6 +671,68 @@ 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(); + EnumTest thirdDay = new EnumTest(Day.WEDNESDAY); + thirdDay.tellItLikeItIs(); + } +} + +// The output is: +// Mondays are bad. +// 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 -- cgit v1.2.3 From 5a8a68988b7c153cf16f37c307954d7070fc9b81 Mon Sep 17 00:00:00 2001 From: Raphael Nascimento Date: Thu, 15 Oct 2015 15:59:22 -0300 Subject: [java/en] Enum Type Outputs in line. --- java.html.markdown | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/java.html.markdown b/java.html.markdown index bc119eb1..8544ecfc 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -719,16 +719,12 @@ public class EnumTest { public static void main(String[] args) { EnumTest firstDay = new EnumTest(Day.MONDAY); - firstDay.tellItLikeItIs(); + firstDay.tellItLikeItIs(); // => Mondays are bad. EnumTest thirdDay = new EnumTest(Day.WEDNESDAY); - thirdDay.tellItLikeItIs(); + thirdDay.tellItLikeItIs(); // => Midweek days are so-so. } } -// The output is: -// Mondays are bad. -// 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 -- cgit v1.2.3 From ef9331fa31ab84e5a04ee024ac490b24a6b5c4dc Mon Sep 17 00:00:00 2001 From: Raphael Nascimento Date: Wed, 21 Oct 2015 09:03:12 -0300 Subject: [java/en] Enum Type --- java.html.markdown | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/java.html.markdown b/java.html.markdown index 8544ecfc..86b0578e 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -7,7 +7,7 @@ contributors: - ["Simon Morgan", "http://sjm.io/"] - ["Zachary Ferguson", "http://github.com/zfergus2"] - ["Cameron Schermerhorn", "http://github.com/cschermerhorn"] - - ["Raphael Nascimento", "http://github.com/raphaelbn"] + - ["Rachel Stiyer", "https://github.com/rstiyer"] filename: LearnJava.java --- @@ -138,7 +138,7 @@ public class LearnJava { // // BigDecimal allows the programmer complete control over decimal // rounding. It is recommended to use BigDecimal with currency values - // and where exact decimal percision is required. + // and where exact decimal precision is required. // // BigDecimal can be initialized with an int, long, double or String // or by initializing the unscaled value (BigInteger) and scale (int). @@ -185,8 +185,12 @@ public class LearnJava { // LinkedLists - Implementation of doubly-linked list. All of the // operations perform as could be expected for a // doubly-linked list. - // Maps - A set of objects that maps keys to values. A map cannot - // contain duplicate keys; each key can map to at most one value. + // 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 + // 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 // interface. This allows the execution time of basic // operations, such as get and insert element, to remain @@ -251,7 +255,7 @@ public class LearnJava { // If statements are c-like int j = 10; - if (j == 10){ + if (j == 10) { System.out.println("I get printed"); } else if (j > 10) { System.out.println("I don't"); @@ -286,7 +290,18 @@ public class LearnJava { // Iterated 10 times, fooFor 0->9 } System.out.println("fooFor Value: " + fooFor); - + + // Nested For Loop Exit with Label + outer: + for (int i = 0; i < 10; i++) { + for (int j = 0; j < 10; j++) { + if (i == 5 && j ==5) { + break outer; + // breaks out of outer loop instead of only the inner one + } + } + } + // For Each Loop // The for loop is also able to iterate over arrays as well as objects // that implement the Iterable interface. @@ -321,7 +336,7 @@ public class LearnJava { // Starting in Java 7 and above, switching Strings works like this: String myAnswer = "maybe"; - switch(myAnswer){ + switch(myAnswer) { case "yes": System.out.println("You answered yes."); break; -- cgit v1.2.3 From 03ef96b2f11133701a3db64b9133f634a9709e94 Mon Sep 17 00:00:00 2001 From: Raphael Nascimento Date: Thu, 29 Oct 2015 12:46:59 -0300 Subject: [java/en] Enum Type --- java.html.markdown | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/java.html.markdown b/java.html.markdown index 86b0578e..1813f81c 100644 --- a/java.html.markdown +++ 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 @@ -450,6 +450,17 @@ class Bicycle { protected int gear; // Protected: Accessible from the class and subclasses String name; // default: Only accessible from within this package + static String className; // Static class variable + + // Static block + // Java has no implementation of static constructors, but + // has a static block that can be used to initialize class variables + // (static variables). + // This block will be called when the class is loaded. + static { + className = "Bicycle"; + } + // Constructors are a way of creating classes // This is a constructor public Bicycle() { @@ -767,7 +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** -- cgit v1.2.3