summaryrefslogtreecommitdiffhomepage
path: root/java.html.markdown
diff options
context:
space:
mode:
Diffstat (limited to 'java.html.markdown')
-rw-r--r--java.html.markdown570
1 files changed, 439 insertions, 131 deletions
diff --git a/java.html.markdown b/java.html.markdown
index f08c4679..84978ecc 100644
--- a/java.html.markdown
+++ b/java.html.markdown
@@ -1,15 +1,19 @@
---
-
language: java
contributors:
- ["Jake Prather", "http://github.com/JakeHP"]
+ - ["Jakukyo Friel", "http://weakish.github.io"]
- ["Madison Dickson", "http://github.com/mix3d"]
+ - ["Simon Morgan", "http://sjm.io/"]
+ - ["Zachary Ferguson", "http://github.com/zfergus2"]
+ - ["Cameron Schermerhorn", "http://github.com/cschermerhorn"]
+ - ["Rachel Stiyer", "https://github.com/rstiyer"]
filename: LearnJava.java
-
---
-Java is a general-purpose, concurrent, class-based, object-oriented computer programming language.
-[Read more here.](http://docs.oracle.com/javase/tutorial/java/index.html)
+Java is a general-purpose, concurrent, class-based, object-oriented computer
+programming language.
+[Read more here.](http://docs.oracle.com/javase/tutorial/java/)
```java
// Single-line comments start with //
@@ -30,26 +34,48 @@ import java.security.*;
// the file.
public class LearnJava {
- // A program must have a main method as an entry point
+ // In order to run a java program, it must have a main method as an entry point.
public static void main (String[] args) {
- // Use System.out.println to print lines
+ // Use System.out.println() to print lines.
System.out.println("Hello World!");
System.out.println(
"Integer: " + 10 +
" Double: " + 3.14 +
" Boolean: " + true);
- // To print without a newline, use System.out.print
+ // To print without a newline, use System.out.print().
System.out.print("Hello ");
System.out.print("World");
+ // Use System.out.printf() for easy formatted printing.
+ System.out.printf("pi = %.5f", Math.PI); // => pi = 3.14159
///////////////////////////////////////
- // Types & Variables
+ // Variables
///////////////////////////////////////
- // Declare a variable using <type> <name> [
+ /*
+ * Variable Declaration
+ */
+ // Declare a variable using <type> <name>
+ int fooInt;
+ // Declare multiple variables of the same type <type> <name1>, <name2>, <name3>
+ int fooInt1, fooInt2, fooInt3;
+
+ /*
+ * Variable Initialization
+ */
+
+ // Initialize a variable using <type> <name> = <val>
+ int fooInt = 1;
+ // Initialize multiple variables of same type with same value <type> <name1>, <name2>, <name3> = <val>
+ int fooInt1, fooInt2, fooInt3;
+ fooInt1 = fooInt2 = fooInt3 = 1;
+
+ /*
+ * Variable types
+ */
// Byte - 8-bit signed two's complement integer
// (-128 <= byte <= 127)
byte fooByte = 100;
@@ -68,14 +94,16 @@ public class LearnJava {
// L is used to denote that this variable value is of type Long;
// anything without is treated as integer by default.
- // Note: Java has no unsigned types
+ // Note: Java has no unsigned types.
// Float - Single-precision 32-bit IEEE 754 Floating Point
+ // 2^-149 <= float <= (2-2^-23) * 2^127
float fooFloat = 234.5f;
- // f is used to denote that this variable value is of type float;
+ // f or F is used to denote that this variable value is of type float;
// otherwise it is treated as double.
// Double - Double-precision 64-bit IEEE 754 Floating Point
+ // 2^-1074 <= x <= (2-2^-52) * 2^1023
double fooDouble = 123.4;
// Boolean - true & false
@@ -85,8 +113,44 @@ public class LearnJava {
// Char - A single 16-bit Unicode character
char fooChar = 'A';
- // final variables can't be reassigned to another object
+ // final variables can't be reassigned to another object,
final int HOURS_I_WORK_PER_WEEK = 9001;
+ // but they can be initialized later.
+ final double E;
+ E = 2.71828;
+
+
+ // BigInteger - Immutable arbitrary-precision integers
+ //
+ // BigInteger is a data type that allows programmers to manipulate
+ // integers longer than 64-bits. Integers are stored as an array of
+ // of bytes and are manipulated using functions built into BigInteger
+ //
+ // BigInteger can be initialized using an array of bytes or a string.
+
+ BigInteger fooBigInteger = new BigInteger(fooByteArray);
+
+
+ // BigDecimal - Immutable, arbitrary-precision signed decimal number
+ //
+ // A BigDecimal takes two parts: an arbitrary precision integer
+ // unscaled value and a 32-bit integer scale
+ //
+ // BigDecimal allows the programmer complete control over decimal
+ // rounding. It is recommended to use BigDecimal with currency values
+ // 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).
+
+ BigDecimal fooBigDecimal = new BigDecimal(fooBigInteger, fooInt);
+
+ // Be wary of the constructor that takes a float or double as
+ // the inaccuracy of the float/double will be copied in BigDecimal.
+ // Prefer the String constructor when you need an exact value.
+
+ BigDecimal tenCents = new BigDecimal("0.1");
+
// Strings
String fooString = "My String Is Here!";
@@ -100,17 +164,17 @@ public class LearnJava {
System.out.println(bazString);
// Arrays
- //The array size must be decided upon instantiation
- //The following formats work for declaring an array
- //<datatype> [] <var name> = new <datatype>[<array size>];
- //<datatype> <var name>[] = new <datatype>[<array size>];
- int [] intArray = new int[10];
- String [] stringArray = new String[1];
- boolean boolArray [] = new boolean[100];
+ // The array size must be decided upon instantiation
+ // The following formats work for declaring an array
+ // <datatype>[] <var name> = new <datatype>[<array size>];
+ // <datatype> <var name>[] = new <datatype>[<array size>];
+ int[] intArray = new int[10];
+ String[] stringArray = new String[1];
+ boolean boolArray[] = new boolean[100];
// Another way to declare & initialize an array
- int [] y = {9000, 1000, 1337};
- String names [] = {"Bob", "John", "Fred", "Juan Pedro"};
+ int[] y = {9000, 1000, 1337};
+ String names[] = {"Bob", "John", "Fred", "Juan Pedro"};
boolean bools[] = new boolean[] {true, false, false};
// Indexing an array - Accessing an element
@@ -121,17 +185,21 @@ public class LearnJava {
System.out.println("intArray @ 1: " + intArray[1]); // => 1
// Others to check out
- // ArrayLists - Like arrays except more functionality is offered,
- // and the size is mutable
+ // ArrayLists - Like arrays except more functionality is offered, and
+ // the size is mutable.
// 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.
- // 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 constant even
- // for large sets.
+ // 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
+ // 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
+ // constant even for large sets.
///////////////////////////////////////
// Operators
@@ -144,7 +212,8 @@ public class LearnJava {
System.out.println("1+2 = " + (i1 + i2)); // => 3
System.out.println("2-1 = " + (i2 - i1)); // => 1
System.out.println("2*1 = " + (i2 * i1)); // => 2
- System.out.println("1/2 = " + (i1 / i2)); // => 0 (0.5 truncated down)
+ System.out.println("1/2 = " + (i1 / i2)); // => 0 (int/int returns an int)
+ System.out.println("1/2 = " + (i1 / (double)i2)); // => 0.5
// Modulo
System.out.println("11%3 = "+(11 % 3)); // => 2
@@ -157,15 +226,20 @@ public class LearnJava {
System.out.println("2 <= 2? " + (2 <= 2)); // => true
System.out.println("2 >= 2? " + (2 >= 2)); // => true
+ // Boolean operators
+ System.out.println("3 > 2 && 2 > 3? " + ((3 > 2) && (2 > 3))); // => false
+ System.out.println("3 > 2 || 2 > 3? " + ((3 > 2) || (2 > 3))); // => true
+ System.out.println("!(3 == 2)? " + (!(3 == 2))); // => true
+
// Bitwise operators!
/*
- ~ Unary bitwise complement
- << Signed left shift
- >> Signed right shift
- >>> Unsigned right shift
- & Bitwise AND
- ^ Bitwise exclusive OR
- | Bitwise inclusive OR
+ ~ Unary bitwise complement
+ << Signed left shift
+ >> Signed/Arithmetic right shift
+ >>> Unsigned/Logical right shift
+ & Bitwise AND
+ ^ Bitwise exclusive OR
+ | Bitwise inclusive OR
*/
// Incrementations
@@ -174,10 +248,10 @@ public class LearnJava {
// The ++ and -- operators increment and decrement by 1 respectively.
// If they are placed before the variable, they increment then return;
// after the variable they return then increment.
- System.out.println(i++); //i = 1, prints 0 (post-increment)
- System.out.println(++i); //i = 2, prints 2 (pre-increment)
- System.out.println(i--); //i = 1, prints 2 (post-decrement)
- System.out.println(--i); //i = 0, prints 0 (pre-decrement)
+ System.out.println(i++); // i = 1, prints 0 (post-increment)
+ System.out.println(++i); // i = 2, prints 2 (pre-increment)
+ System.out.println(i--); // i = 1, prints 2 (post-decrement)
+ System.out.println(--i); // i = 0, prints 0 (pre-decrement)
///////////////////////////////////////
// Control Structures
@@ -186,7 +260,7 @@ 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");
@@ -196,81 +270,104 @@ public class LearnJava {
// While loop
int fooWhile = 0;
- while(fooWhile < 100)
- {
- //System.out.println(fooWhile);
- //Increment the counter
- //Iterated 100 times, fooWhile 0,1,2...99
+ while(fooWhile < 100) {
+ System.out.println(fooWhile);
+ // Increment the counter
+ // Iterated 100 times, fooWhile 0,1,2...99
fooWhile++;
}
System.out.println("fooWhile Value: " + fooWhile);
// Do While Loop
int fooDoWhile = 0;
- do
- {
- //System.out.println(fooDoWhile);
- //Increment the counter
- //Iterated 99 times, fooDoWhile 0->99
+ do {
+ System.out.println(fooDoWhile);
+ // Increment the counter
+ // Iterated 99 times, fooDoWhile 0->99
fooDoWhile++;
- }while(fooDoWhile < 100);
+ } while(fooDoWhile < 100);
System.out.println("fooDoWhile Value: " + fooDoWhile);
// For Loop
- int fooFor;
- //for loop structure => for(<start_statement>; <conditional>; <step>)
- for(fooFor=0; fooFor<10; fooFor++){
- //System.out.println(fooFor);
- //Iterated 10 times, fooFor 0->9
+ // for loop structure => for(<start_statement>; <conditional>; <step>)
+ for (int fooFor = 0; fooFor < 10; fooFor++) {
+ System.out.println(fooFor);
+ // 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
- // An automatic iteration through an array or list of objects.
- int[] fooList = {1,2,3,4,5,6,7,8,9};
- //for each loop structure => for(<object> : <array_object>)
- //reads as: for each object in the array
- //note: the object type must match the array.
-
- for( int bar : fooList ){
- //System.out.println(bar);
+ // The for loop is also able to iterate over arrays as well as objects
+ // that implement the Iterable interface.
+ int[] fooList = {1, 2, 3, 4, 5, 6, 7, 8, 9};
+ // for each loop structure => for (<object> : <iterable>)
+ // reads as: for each element in the iterable
+ // note: the object type must match the element type of the iterable.
+
+ for (int bar : fooList) {
+ System.out.println(bar);
//Iterates 9 times and prints 1-9 on new lines
}
// Switch Case
// A switch works with the byte, short, char, and int data types.
- // It also works with enumerated types (discussed in Enum Types),
- // the String class, and a few special classes that wrap
- // primitive types: Character, Byte, Short, and Integer.
+ // It also works with enumerated types (discussed in Enum Types), the
+ // String class, and a few special classes that wrap primitive types:
+ // Character, Byte, Short, and Integer.
int month = 3;
String monthString;
- switch (month){
- case 1:
- monthString = "January";
+ switch (month) {
+ case 1: monthString = "January";
break;
- case 2:
- monthString = "February";
+ case 2: monthString = "February";
break;
- case 3:
- monthString = "March";
- break;
- default:
- monthString = "Some other month";
+ case 3: monthString = "March";
break;
+ default: monthString = "Some other month";
+ break;
}
System.out.println("Switch Case Result: " + monthString);
+
+ // Starting in Java 7 and above, switching Strings works like this:
+ String myAnswer = "maybe";
+ switch(myAnswer) {
+ case "yes":
+ System.out.println("You answered yes.");
+ break;
+ case "no":
+ System.out.println("You answered no.");
+ break;
+ case "maybe":
+ System.out.println("You answered maybe.");
+ break;
+ default:
+ System.out.println("You answered " + myAnswer);
+ break;
+ }
// Conditional Shorthand
// You can use the '?' operator for quick assignments or logic forks.
- // Reads as "If (statement) is true, use <first value>, otherwise, use <second value>"
+ // Reads as "If (statement) is true, use <first value>, otherwise, use
+ // <second value>"
int foo = 5;
String bar = (foo < 10) ? "A" : "B";
System.out.println(bar); // Prints A, because the statement is true
- ///////////////////////////////////////
- // Converting Data Types And Typcasting
- ///////////////////////////////////////
+ ////////////////////////////////////////
+ // Converting Data Types And Typecasting
+ ////////////////////////////////////////
// Converting data
@@ -286,9 +383,8 @@ public class LearnJava {
// String
// Typecasting
- // You can also cast java objects, there's a lot of details and
- // deals with some more intermediate concepts.
- // Feel free to check it out here:
+ // You can also cast Java objects, there's a lot of details and deals
+ // with some more intermediate concepts. Feel free to check it out here:
// http://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html
@@ -310,17 +406,45 @@ public class LearnJava {
// toString returns this Object's string representation.
System.out.println("trek info: " + trek.toString());
+ // Double Brace Initialization
+ // The Java Language has no syntax for how to create static Collections
+ // in an easy way. Usually you end up in the following way:
+
+ private static final Set<String> COUNTRIES = new HashSet<String>();
+ static {
+ validCodes.add("DENMARK");
+ validCodes.add("SWEDEN");
+ validCodes.add("FINLAND");
+ }
+
+ // But there's a nifty way to achieve the same thing in an
+ // easier way, by using something that is called Double Brace
+ // Initialization.
+
+ private static final Set<String> COUNTRIES = new HashSet<String>() {{
+ add("DENMARK");
+ add("SWEDEN");
+ add("FINLAND");
+ }}
+
+ // The first brace is creating a new AnonymousInnerClass and the
+ // second one declares an instance initializer block. This block
+ // is called when the anonymous inner class is created.
+ // This does not only work for Collections, it works for all
+ // non-final classes.
+
} // End main method
} // End LearnJava class
-// You can include other, non-public outer-level classes in a .java file
+// You can include other, non-public outer-level classes in a .java file,
+// but it is good practice. Instead split classes into separate files.
// Class Declaration Syntax:
-// <public/private/protected> class <class name>{
-// //data fields, constructors, functions all inside.
-// //functions are called as methods in Java.
+// <public/private/protected> class <class name> {
+// // data fields, constructors, functions all inside.
+// // functions are called as methods in Java.
// }
class Bicycle {
@@ -331,9 +455,22 @@ 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() {
+ // You can also call another constructor:
+ // this(1, 50, 5, "Bontrager");
gear = 1;
cadence = 50;
speed = 5;
@@ -341,20 +478,21 @@ class Bicycle {
}
// This is a constructor that takes arguments
- public Bicycle(int startCadence, int startSpeed, int startGear, String name) {
+ public Bicycle(int startCadence, int startSpeed, int startGear,
+ String name) {
this.gear = startGear;
this.cadence = startCadence;
this.speed = startSpeed;
this.name = name;
}
- // Function Syntax:
+ // Method Syntax:
// <public/private/protected> <return type> <function name>(<args>)
// Java classes often implement getters and setters for their fields
// Method declaration syntax:
- // <scope> <return type> <method name>(<args>)
+ // <access modifier> <return type> <method name>(<args>)
public int getCadence() {
return cadence;
}
@@ -385,12 +523,10 @@ class Bicycle {
}
//Method to display the attribute values of this Object.
- @Override
+ @Override // Inherited from the Object class.
public String toString() {
- return "gear: " + gear +
- " cadence: " + cadence +
- " speed: " + speed +
- " name: " + name;
+ return "gear: " + gear + " cadence: " + cadence + " speed: " + speed +
+ " name: " + name;
}
} // end class Bicycle
@@ -404,56 +540,228 @@ class PennyFarthing extends Bicycle {
super(startCadence, startSpeed, 0, "PennyFarthing");
}
- // You should mark a method you're overriding with an @annotation
- // To learn more about what annotations are and their purpose
- // check this out: http://docs.oracle.com/javase/tutorial/java/annotations/
+ // You should mark a method you're overriding with an @annotation.
+ // To learn more about what annotations are and their purpose check this
+ // out: http://docs.oracle.com/javase/tutorial/java/annotations/
@Override
public void setGear(int gear) {
gear = 0;
}
-
}
-//Interfaces
-//Interface declaration syntax
-//<access-level> interface <interface-name> extends <super-interfaces> {
-// //Constants
-// //Method declarations
-//}
+// Interfaces
+// Interface declaration syntax
+// <access-level> interface <interface-name> extends <super-interfaces> {
+// // Constants
+// // Method declarations
+// }
-//Example - Food:
+// Example - Food:
public interface Edible {
- public void eat(); //Any class that implements this interface, must implement this method
+ public void eat(); // Any class that implements this interface, must
+ // implement this method.
}
public interface Digestible {
- public void digest();
+ public void digest();
}
-//We can now create a class that implements both of these interfaces
+// We can now create a class that implements both of these interfaces.
public class Fruit implements Edible, Digestible {
- public void eat() {
- //...
- }
+
+ @Override
+ public void eat() {
+ // ...
+ }
- public void digest() {
- //...
- }
+ @Override
+ public void digest() {
+ // ...
+ }
}
-//In java, you can extend only one class, but you can implement many interfaces.
-//For example:
-public class ExampleClass extends ExampleClassParent implements InterfaceOne, InterfaceTwo {
- public void InterfaceOneMethod() {
+// In Java, you can extend only one class, but you can implement many
+// interfaces. For example:
+public class ExampleClass extends ExampleClassParent implements InterfaceOne,
+ InterfaceTwo {
- }
+ @Override
+ public void InterfaceOneMethod() {
+ }
- public void InterfaceTwoMethod() {
+ @Override
+ public void InterfaceTwoMethod() {
+ }
- }
}
+// Abstract Classes
+
+// Abstract Class declaration syntax
+// <access-level> abstract <abstract-class-name> extends <super-abstract-classes> {
+// // Constants and variables
+// // Method declarations
+// }
+
+// Marking a class as abstract means that it contains abstract methods that must
+// be defined in a child class. Similar to interfaces, abstract classes cannot
+// be instantiated, but instead must be extended and the abstract methods
+// defined. Different from interfaces, abstract classes can contain a mixture of
+// concrete and abstract methods. Methods in an interface cannot have a body,
+// unless the method is static, and variables are final by default, unlike an
+// abstract class. Also abstract classes CAN have the "main" method.
+
+public abstract class Animal
+{
+ public abstract void makeSound();
+
+ // Method can have a body
+ public void eat()
+ {
+ System.out.println("I am an animal and I am Eating.");
+ // Note: We can access private variable here.
+ age = 30;
+ }
+
+ // No need to initialize, however in an interface
+ // a variable is implicitly final and hence has
+ // to be initialized.
+ protected int age;
+
+ public void printAge()
+ {
+ System.out.println(age);
+ }
+
+ // Abstract classes can have main function.
+ public static void main(String[] args)
+ {
+ System.out.println("I am abstract");
+ }
+}
+
+class Dog extends Animal
+{
+ // Note still have to override the abstract methods in the
+ // abstract class.
+ @Override
+ public void makeSound()
+ {
+ System.out.println("Bark");
+ // age = 30; ==> ERROR! age is private to Animal
+ }
+
+ // NOTE: You will get an error if you used the
+ // @Override annotation here, since java doesn't allow
+ // overriding of static methods.
+ // What is happening here is called METHOD HIDING.
+ // Check out this awesome SO post: http://stackoverflow.com/questions/16313649/
+ public static void main(String[] args)
+ {
+ Dog pluto = new Dog();
+ pluto.makeSound();
+ pluto.eat();
+ pluto.printAge();
+ }
+}
+
+// Final Classes
+
+// Final Class declaration syntax
+// <access-level> final <final-class-name> {
+// // Constants and variables
+// // Method declarations
+// }
+
+// Final classes are classes that cannot be inherited from and are therefore a
+// final child. In a way, final classes are the opposite of abstract classes
+// because abstract classes must be extended, but final classes cannot be
+// extended.
+public final class SaberToothedCat extends Animal
+{
+ // Note still have to override the abstract methods in the
+ // abstract class.
+ @Override
+ public void makeSound()
+ {
+ System.out.println("Roar");
+ }
+}
+
+// Final Methods
+public abstract class Mammal()
+{
+ // Final Method Syntax:
+ // <access modifier> final <return type> <function name>(<args>)
+
+ // Final methods, like, final classes cannot be overridden by a child class,
+ // and are therefore the final implementation of the method.
+ public final boolean isWarmBlooded()
+ {
+ 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
@@ -477,7 +785,7 @@ 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**
@@ -490,8 +798,8 @@ The links provided here below are just to get an understanding of the topic, fee
* [Head First Java](http://www.headfirstlabs.com/books/hfjava/)
+* [Thinking in Java](http://www.mindview.net/Books/TIJ/)
+
* [Objects First with Java](http://www.amazon.com/Objects-First-Java-Practical-Introduction/dp/0132492660)
* [Java The Complete Reference](http://www.amazon.com/gp/product/0071606300)
-
-