[java/fa]add java for Persian Language (#2701)

* create java

* add Farsi java

* add -fa

1 files changed, 899 insertions, 0 deletions

diff --git a/fa-ir/java-fa.html.markdown b/fa-ir/java-fa.html.markdown
new file mode 100644
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@@ -0,0 +1,899 @@
+---
+language: java
+contributors:
+    - ["Jake Prather", "https://github.com/JakeHP"]
+    - ["Jakukyo Friel", "https://weakish.github.io"]
+    - ["Madison Dickson", "https://github.com/mix3d"]
+    - ["Simon Morgan", "https://sjm.io/"]
+    - ["Zachary Ferguson", "https://github.com/zfergus2"]
+    - ["Cameron Schermerhorn", "https://github.com/cschermerhorn"]
+    - ["Rachel Stiyer", "https://github.com/rstiyer"]
+    - ["Michael Dähnert", "https://github.com/JaXt0r"]
+    - ["Rob Rose", "https://github.com/RobRoseKnows"]
+    - ["Sean Nam", "https://github.com/seannam"]
+filename: LearnJava-fa.java
+---
+
+جاوا یک زبان برنامه نویسی کامپیوتری چند منظوره، با قابلیت همزمانی، برپایه کلاس و شی گرایی می باشد.
+[مطالعه بیشتر.](https://docs.oracle.com/javase/tutorial/java/)
+
+```java
+// Single-line comments start with //
+
+/*
+Multi-line comments look like this.
+*/
+
+/**
+ * JavaDoc comments look like this. Used to describe the Class or various
+ * attributes of a Class.
+ * Main attributes:
+ *
+ * @author         @ghaseminya
+ * @version     v1.0
+*/
+
+// Import ArrayList class inside of the java.util package
+import java.util.ArrayList;
+// Import all classes inside of java.security package
+import java.security.*;
+
+// Each .java file contains one outer-level public class, with the same name
+// as the file.
+public class LearnJava {
+
+    // In order to run a java program, it must have a main method as an entry 
+    // point.
+    public static void main (String[] args) {
+
+    ///////////////////////////////////////
+    // Input/Output
+    ///////////////////////////////////////
+
+        /*
+        * Ouput
+        */
+
+        // 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().
+        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
+
+        /*
+         * Input
+         */
+
+        // use Scanner to read input
+        // must import java.util.Scanner;
+        Scanner scanner = new Scanner(System.in);
+
+        // read string input
+        String name = scanner.next();
+
+        // read byte input
+        byte numByte = scanner.nextByte();
+
+        // read int input
+        int numInt = scanner.nextInt();
+
+        // read long input
+        float numFloat - scanner.nextFloat();
+
+        // read double input
+        double numDouble = scanner.nextDouble();
+
+        // read boolean input
+        boolean bool = scanner.nextBoolean();
+
+        ///////////////////////////////////////
+        // Variables
+        ///////////////////////////////////////
+
+        /*
+        *  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 barInt = 1;
+        // Initialize multiple variables of same type with same 
+        // value <type> <name1>, <name2>, <name3> = <val>
+        int barInt1, barInt2, barInt3;
+        barInt1 = barInt2 = barInt3 = 1;
+
+        /*
+        *  Variable types
+        */
+        // Byte - 8-bit signed two's complement integer
+        // (-128 <= byte <= 127)
+        byte fooByte = 100;
+        
+        // If you would like to interpret a byte as an unsigned integer
+        // then this simple operation can help
+        int unsignedIntLessThan256 = 0xff & fooByte;
+        // this contrasts a cast which can be negative.
+        int signedInt = (int) fooByte;
+
+        // Short - 16-bit signed two's complement integer
+        // (-32,768 <= short <= 32,767)
+        short fooShort = 10000;
+
+        // Integer - 32-bit signed two's complement integer
+        // (-2,147,483,648 <= int <= 2,147,483,647)
+        int bazInt = 1;
+
+        // Long - 64-bit signed two's complement integer
+        // (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807)
+        long fooLong = 100000L;
+        // L is used to denote that this variable value is of type Long;
+        // anything without is treated as integer by default.
+
+        // Note: byte, short, int and long are signed. They can have positive and negative values.
+        // There are no unsigned variants.
+        // char, however, is 16-bit unsigned.
+
+        // Float - Single-precision 32-bit IEEE 754 Floating Point
+        // 2^-149 <= float <= (2-2^-23) * 2^127
+        float fooFloat = 234.5f;
+        // 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
+        boolean fooBoolean = true;
+        boolean barBoolean = false;
+
+        // Char - A single 16-bit Unicode character
+        char fooChar = 'A';
+
+        // 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!";
+
+        // \n is an escaped character that starts a new line
+        String barString = "Printing on a new line?\nNo Problem!";
+        // \t is an escaped character that adds a tab character
+        String bazString = "Do you want to add a tab?\tNo Problem!";
+        System.out.println(fooString);
+        System.out.println(barString);
+        System.out.println(bazString);
+
+        // String Building
+        // #1 - with plus operator
+        // That's the basic way to do it (optimized under the hood)
+        String plusConcatenated = "Strings can " + "be concatenated " + "via + operator.";
+        System.out.println(plusConcatenated);
+        // Output: Strings can be concatenated via + operator.
+
+        // #2 - with StringBuilder
+        // This way doesn't create any intermediate strings. It just stores the string pieces, and ties them together
+        // when toString() is called.
+        // Hint: This class is not thread safe. A thread-safe alternative (with some impact on performance) is StringBuffer.
+        StringBuilder builderConcatenated = new StringBuilder();
+        builderConcatenated.append("You ");
+        builderConcatenated.append("can use ");
+        builderConcatenated.append("the StringBuilder class.");
+        System.out.println(builderConcatenated.toString()); // only now is the string built 
+        // Output: You can use the StringBuilder class.
+        
+        // StringBuilder is efficient when the fully constructed String is not required until the end of some processing.
+        StringBuilder stringBuilder = new StringBuilder();
+        String inefficientString = "";
+        for(int i = 0 ; i < 10; i++){
+            stringBuilder.append(i).append(" ");
+            inefficientString += i + " ";
+        }
+        System.out.println(inefficientString);
+        System.out.println(stringBuilder.toString());
+        // inefficientString requires a lot more work to produce, as it generates a String on every loop iteration.
+        // Simple concatenation with + is compiled to a StringBuilder and toString()
+        // Avoid string concatenation in loops.
+        
+        // #3 - with String formatter
+        // Another alternative way to create strings. Fast and readable.
+        String.format("%s may prefer %s.", "Or you", "String.format()");
+        // Output: Or you may prefer String.format().
+ 
+        // 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];
+
+        // Another way to declare & initialize an array
+        int[] y = {9000, 1000, 1337};
+        String names[] = {"Bob", "John", "Fred", "Juan Pedro"};
+        boolean bools[] = {true, false, false};
+
+        // Indexing an array - Accessing an element
+        System.out.println("intArray @ 0: " + intArray[0]);
+
+        // Arrays are zero-indexed and mutable.
+        intArray[1] = 1;
+        System.out.println("intArray @ 1: " + intArray[1]); // => 1
+
+        // Other data types worth checking out
+        // 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 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.
+        // TreeMap - This class is a sorted tree structure. It implements a red
+        //           black tree and sorts the entries based on the key value or
+        //           the comparator provided while creating the object
+
+        ///////////////////////////////////////
+        // Operators
+        ///////////////////////////////////////
+        System.out.println("\n->Operators");
+
+        int i1 = 1, i2 = 2; // Shorthand for multiple declarations
+
+        // Arithmetic is straightforward
+        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 (int/int returns int)
+        System.out.println("1/2 = " + (i1 / (double)i2)); // => 0.5
+
+        // Modulo
+        System.out.println("11%3 = "+(11 % 3)); // => 2
+
+        // Comparison operators
+        System.out.println("3 == 2? " + (3 == 2)); // => false
+        System.out.println("3 != 2? " + (3 != 2)); // => true
+        System.out.println("3 > 2? " + (3 > 2)); // => true
+        System.out.println("3 < 2? " + (3 < 2)); // => false
+        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/Arithmetic right shift
+        >>>    Unsigned/Logical right shift
+        &      Bitwise AND
+        ^      Bitwise exclusive OR
+        |      Bitwise inclusive OR
+        */
+
+        // Increment operators
+        int i = 0;
+        System.out.println("\n->Inc/Dec-rementation");
+        // 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)
+
+        ///////////////////////////////////////
+        // Control Structures
+        ///////////////////////////////////////
+        System.out.println("\n->Control Structures");
+
+        // If statements are c-like
+        int j = 10;
+        if (j == 10) {
+            System.out.println("I get printed");
+        } else if (j > 10) {
+            System.out.println("I don't");
+        } else {
+            System.out.println("I also don't");
+        }
+
+        // While loop
+        int fooWhile = 0;
+        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
+            fooDoWhile++;
+        } while(fooDoWhile < 100);
+        System.out.println("fooDoWhile Value: " + fooDoWhile);
+
+        // For Loop
+        // 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
+        // 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.
+        int month = 3;
+        String monthString;
+        switch (month) {
+            case 1: monthString = "January";
+                    break;
+            case 2: monthString = "February";
+                    break;
+            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;
+        }
+        
+        
+        // Try-with-resources (Java 7+)
+        // Try-catch-finally statements work as expected in Java but in Java 7+
+        // the try-with-resources statement is also available. Try-with-resources
+        // simplifies try-catch-finally statements be closing resources
+        // automatically.
+        
+        // In order to use a try-with-resources, include a an instance of a class
+        // in the try statement. The class must implement java.lang.AutoCloseable.
+        try(BufferedReader br = new BufferedReader(new FileReader("foo.txt"))) {
+            // You can attempt to do something that could throw an exception.
+            System.out.println(br.readLine());
+            // In Java 7, the resource will always be closed, even if it throws
+            // an Exception. 
+        } catch (Exception ex) {
+            //The resource will be closed before the catch statement executes.
+            System.out.println("readLine() failed.");
+        }
+        // No need for a finally statement in this case, the BufferedReader is
+        // already closed. This can be used to avoid certain edge cases where
+        // a finally statement might not be called.
+        // To learn more:
+        // https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html
+        
+        
+        // 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>"
+        int foo = 5;
+        String bar = (foo < 10) ? "A" : "B";
+        System.out.println(bar); // Prints A, because the statement is true
+
+        ////////////////////////////////////////
+        // Converting Data Types And Typecasting
+        ////////////////////////////////////////
+
+        // Converting data
+
+        // Convert String To Integer
+        Integer.parseInt("123");//returns an integer version of "123"
+
+        // Convert Integer To String
+        Integer.toString(123);//returns a string version of 123
+
+        // For other conversions check out the following classes:
+        // Double
+        // Long
+        // 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:
+        // https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html
+
+        ///////////////////////////////////////
+        // Classes And Functions
+        ///////////////////////////////////////
+
+        System.out.println("\n->Classes & Functions");
+
+        // (definition of the Bicycle class follows)
+
+        // Use new to instantiate a class
+        Bicycle trek = new Bicycle();
+
+        // Call object methods
+        trek.speedUp(3); // You should always use setter and getter methods
+        trek.setCadence(100);
+
+        // 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 {
+           COUNTRIES.add("DENMARK");
+           COUNTRIES.add("SWEDEN");
+           COUNTRIES.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,
+// but it is not 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.
+// }
+
+class Bicycle {
+
+    // Bicycle's Fields/Variables
+    public int cadence; // Public: Can be accessed from anywhere
+    private int speed;  // Private: Only accessible from within the class
+    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;
+        name = "Bontrager";
+    }
+    // This is a constructor that takes arguments
+    public Bicycle(int startCadence, int startSpeed, int startGear,
+        String name) {
+        this.gear = startGear;
+        this.cadence = startCadence;
+        this.speed = startSpeed;
+        this.name = name;
+    }
+
+    // Method Syntax:
+    // <public/private/protected> <return type> <function name>(<args>)
+
+    // Java classes often implement getters and setters for their fields
+
+    // Method declaration syntax:
+    // <access modifier> <return type> <method name>(<args>)
+    public int getCadence() {
+        return cadence;
+    }
+
+    // void methods require no return statement
+    public void setCadence(int newValue) {
+        cadence = newValue;
+    }
+    public void setGear(int newValue) {
+        gear = newValue;
+    }
+    public void speedUp(int increment) {
+        speed += increment;
+    }
+    public void slowDown(int decrement) {
+        speed -= decrement;
+    }
+    public void setName(String newName) {
+        name = newName;
+    }
+    public String getName() {
+        return name;
+    }
+
+    //Method to display the attribute values of this Object.
+    @Override // Inherited from the Object class.
+    public String toString() {
+        return "gear: " + gear + " cadence: " + cadence + " speed: " + speed +
+            " name: " + name;
+    }
+} // end class Bicycle
+
+// PennyFarthing is a subclass of Bicycle
+class PennyFarthing extends Bicycle {
+    // (Penny Farthings are those bicycles with the big front wheel.
+    // They have no gears.)
+
+    public PennyFarthing(int startCadence, int startSpeed) {
+        // Call the parent constructor with super
+        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/
+    @Override
+    public void setGear(int gear) {
+        this.gear = 0;
+    }
+}
+
+// Interfaces
+// Interface declaration syntax
+// <access-level> interface <interface-name> extends <super-interfaces> {
+//     // Constants
+//     // Method declarations
+// }
+
+// Example - Food:
+public interface Edible {
+    public void eat(); // Any class that implements this interface, must
+                       // implement this method.
+}
+
+public interface Digestible {
+    public void digest();
+    // In Java 8, interfaces can have default method.
+    // public void digest() {
+    //     System.out.println("digesting ...");
+    // }
+}
+
+// We can now create a class that implements both of these interfaces.
+public class Fruit implements Edible, Digestible {
+    @Override
+    public void eat() {
+        // ...
+    }
+
+    @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 {
+    @Override
+    public void InterfaceOneMethod() {
+    }
+
+    @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
+// concrete and abstract methods. Methods in an interface cannot have a body,
+// mixture of 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 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 see more at https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html
+
+```
+
+## مطالب بیشتر
+
+لینکهای زیر را می توانید برای پیگیرهای بیشتر استفاده کنید.
+البته همیشه گوگل را در کنار دستتان داشته باشید!
+
+**سایت های راهنمای اصلی**:
+
+* [Java Tutorial Trail from Sun / Oracle](https://docs.oracle.com/javase/tutorial/index.html)
+
+* [Java Access level modifiers](https://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html)
+
+* [Object-Oriented Programming Concepts](https://docs.oracle.com/javase/tutorial/java/concepts/index.html):
+    * [Inheritance](https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html)
+    * [Polymorphism](https://docs.oracle.com/javase/tutorial/java/IandI/polymorphism.html)
+    * [Abstraction](https://docs.oracle.com/javase/tutorial/java/IandI/abstract.html)
+
+* [Exceptions](https://docs.oracle.com/javase/tutorial/essential/exceptions/index.html)
+
+* [Interfaces](https://docs.oracle.com/javase/tutorial/java/IandI/createinterface.html)
+
+* [Generics](https://docs.oracle.com/javase/tutorial/java/generics/index.html)
+
+* [Java Code Conventions](https://www.oracle.com/technetwork/java/codeconvtoc-136057.html)
+
+* New features in Java 8:
+    * [Lambda expressions (functional programming)](https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html)
+    * [Date and time API (java.time package)](http://www.oracle.com/technetwork/articles/java/jf14-date-time-2125367.html)
+
+**راهنما و سایت های آموزشی**
+
+* [Learneroo.com - Learn Java](http://www.learneroo.com)
+
+* [Codingbat.com](http://codingbat.com/java)
+
+**کتاب‌ها**:
+
+* [Head First Java](http://www.headfirstlabs.com/books/hfjava/)
+
+* [Thinking in Java](http://www.mindview.net/Books/TIJ/)
+
+* [Objects First with Java](https://www.amazon.com/Objects-First-Java-Practical-Introduction/dp/0132492660)
+
+* [Java The Complete Reference](https://www.amazon.com/gp/product/0071606300)