update prereadings

.gitignore

@@ -4,8 +4,13 @@
 .mtj.tmp/
 
 # Package Files #
+*.jar
 *.war
 *.ear
 
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
+
+# IntelliJ specific files #
+*.idea/
+*.iml

week1/2-OOP/prereading.md

@@ -1,32 +1,80 @@
 *On OOP in General*
-https://www.youtube.com/watch?v=lbXsrHGhBAU
+https://www.youtube.com/watch?v=lbXsrHGhBAU 
+
+*Q&A* 
+
+* What are the main principles of OOP programming?
+* What is Polymorphism?
+* What is Encapsolation?
+* What is Data Abstraction?
+* What is Inheritance?
+* Whis is the founding principle...? 
+
+*Time : 30 min*
 
 *OOP Trail @ Oracle*
 http://docs.oracle.com/javase/tutorial/java/concepts/index.html
+*Time : 15 min*
+
 
 *Class and Objects @ Oracle (Those pages are actually Sun's property!)*
 http://docs.oracle.com/javase/tutorial/java/javaOO/
 http://docs.oracle.com/javase/tutorial/java/concepts/object.html
 
+*Q&A*
+* What is Class?
+* What is Interface?
+* What is isntace field, what is class field?
+* How is the behaviour of the class defined?
+* What is "this" keyword? How it is used?
+
+*Time : 30 min*
+
 *More on Classes and objects*
 http://www.javaworld.com/article/2075202/core-java/object-oriented-language-basics-part-1.html?page=1
 
+*Time : 15 min*
+
 *Constructors & new()*
 http://www.javaworld.com/article/2076204/core-java/understanding-constructors.html
 http://www.javaworld.com/article/2076614/core-java/object-initialization-in-java.html
 
+*Q&A*
+* Default init values ?
+* What if I use return in constructor?
+* Usage of super and this in constructors? Where they should be put in the constructor?
+* Usage of try/catch in contructors?
+
+*Time : 45 min*
+
 *Abstract classes vs Interfaces*
 http://www.programmerinterview.com/index.php/java-questions/interface-vs-abstract-class/
 http://www.javaworld.com/article/2077421/learn-java/abstract-classes-vs-interfaces.html?null
 
+*Time : 15 min*
+
 *Override, overload, hide*
 http://docs.oracle.com/javase/tutorial/java/IandI/override.html
 
+*Q&A*
+* What is @Override annotation?
+* Default methods in interfaces? Their scope and how are they hidden?
+
+*Time : 20 min*
+
 *Subtyping & Liskov principle*
 https://www.youtube.com/watch?v=IL61KMYK0b8
+*Q&A*
+*What is Liskov principle?*
+
+*Time : 10 min*
 
 *Default Methods*
 http://docs.oracle.com/javase/tutorial/java/IandI/defaultmethods.html
 
+*Time : 20 min*
+
 *Invariants*
 http://people.cs.aau.dk/~normark/oop-csharp/html/notes/contracts_themes-class-inv-sect.html
+
+*Time : 20 min*

week2/1-CollectionsAndGenerics1/README.md

@@ -38,6 +38,7 @@ boundedQueue.offer(4);
 boundedQueue.offer(5);
 System.out.println(boundedQueue.toString()); //3,4,5
 ```
+*Hint:* View the java impl and interface:)
 
 ###4.Rotate the elements of a collection###
 Make a void *utility* method that rotates the contents of a collection.
@@ -78,6 +79,8 @@ Lets say you have a `List<Student>`, where a Student is a class, containing two
 
 Sort them by their grades first. Their grades actually are integers => 2,3,4,5,6. If two students happen to have the same grades, sort those two by their names.
 
+*hint* : Use Comparable or Comparator
+
 ###8.Give me the median, quick!###
 Make an interface `Statistics`, which has these operations:
 
@@ -145,6 +148,8 @@ System.out.println(todo.getTimeNeeded()) //sum of the time needed for every task
 See Comparable and Comparator classes in Java. Check out the PriorityQueue class.
 http://javarevisited.blogspot.com/2011/06/comparator-and-comparable-in-java.html
 
+Use of generic classes.
+
 ###10.Make a utility method that converts a hashMap into a very human-readable string###
 Make a *utility* method that takes a `HashMap<? extends Object, ? extends Object>`
 and *returns a String*, representing the HashMap.
@@ -178,6 +183,10 @@ Retain the ordering of the elements!
 
 ##Epic bonus!##
 ###Cryptoanalysis fun###
+=======
+*Hint*
+LinkedHashMap
+
 There is an old technique for encrypting messages - shuffling the letters. For instance, if we take the string `Godzilla`, one crypted version of it 
 is `Mrezotti`.
 The cipher here is

week2/1-CollectionsAndGenerics1/prereading.md

@@ -1,26 +1,58 @@
 *Simplest use of an ArrayList*
 http://www.mkyong.com/java/how-to-loop-arraylist-in-java/
 
+*Time : 15 min*
+
 *Check out some of the public methods of ArrayList*
 See its behaviour, what it can and can't do :)  
 http://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html
 
+*Q&A*
+* How would you implement a ArrayList
+
+*Time : 30 min*
+
 *Some examples of the most used collections class in Java: ArrayList*
 http://javarevisited.blogspot.com/2011/05/example-of-arraylist-in-java-tutorial.html
 
+*Time : 30 min*
+
 *Difference between Iterator and ListIterator* (if you are unfamiliar with iterators, skip this one for now : )
 http://stackoverflow.com/questions/10977992/difference-between-iterator-and-listiterator
 
+*Time : 15 min*
+
 *Diagram of ALL of java's collections framework:*
 http://www.codejava.net/java-core/collections/overview-of-java-collections-framework-api-uml-diagram
 
+*Q&A*
+* What is Set
+* What is Map
+* What do you understand about generics
+
+*Time : 20 min*
+
 ####Part 2####
 *A HashMap example*  
 http://www.tutorialspoint.com/java/java_hashmap_class.htm
 
+*Time : 30 min*
+
 *HashMap vs Hashtable vs TreeMap in Java*  
 http://www.programcreek.com/2013/03/hashmap-vs-treemap-vs-hashtable-vs-linkedhashmap/
 
+*Q&A*
+* Differences between all 
+
+*Time : 30 min*
+
 *Equals and hashcode in java*  
 http://stackoverflow.com/questions/27581/overriding-equals-and-hashcode-in-java
 
+*Q&A*
+* Mutable keys in Maps
+
+*Time : 20 min*
+
+*Additional reading*
+http://javarevisited.blogspot.com/2013/10/what-is-priorityqueue-data-structure-java-example-tutorial.html

week2/2-Exceptions/prereading.md

@@ -1,9 +1,25 @@
 *Exceptions hierarch in Java*
 http://www.javamex.com/tutorials/exceptions/exceptions_hierarchy.shtml
 
+*Q&A*
+* What is Throwable?
+* What is Error?
+* What is runtime exception?
+* What is checked/uncheck exeption?
+* What throw does in method?
+* What is throws declaration of a method?
+* EPIC QUESTION : What is Thread.setDefaultUncaughtExceptionHandler()?
+
+*Time : 30 min*
+
 *Try/catch/finally example* 
 http://www.tutorialspoint.com/java/java_exceptions.htm
 
+*Q&A*
+*What is the purpose of try/catch/finnaly? Give example with resources! What are the tricky parts this scheme?
+
+*Time : 30 min*
+
 *Try with resources in Java 7*
 http://www.mkyong.com/java/try-with-resources-example-in-jdk-7/
 

week6/1-Multithreading/Core_Java_2_week6/src/com/hackbulgaria/corejava/WaitNotifyMechanism.java

@@ -0,0 +1,66 @@
+package com.hackbulgaria.corejava;
+
+public class WaitNotifyMechanism {
+    public static long startTime = System.currentTimeMillis();
+    public static Integer counter = 0;
+    public static final Object monitor = new Object();
+    private static int turn = 0;
+
+    public static void increment() {
+        System.out.println("Incrementing from Thread : " + Thread.currentThread().getName() + " " + counter );
+        counter++;
+    }
+
+    public static void main(String[] args) throws InterruptedException {
+        Thread t1 = new Thread() {
+            public void run() {
+                for (int i = 0; i < 2_000_000; i++) {
+                    synchronized (monitor) {
+                        while (turn != 1) {
+                            try {
+                                monitor.wait();
+                            } catch (InterruptedException e) {
+                                e.printStackTrace();
+                            }
+
+                        }
+                        increment();
+
+                        turn = (turn + 1) % 2;
+                        monitor.notify();
+                    }
+
+                }
+            }
+        };
+        Thread t2 = new Thread() {
+
+            public void run() {
+                for (int i = 0; i < 2_000_000; i++) {
+                    synchronized (monitor) {
+                        while (turn != 0) {
+                            try {
+                                monitor.wait();
+                            } catch (InterruptedException e) {
+                                e.printStackTrace();
+                            }
+                        }
+
+                        increment();
+
+                        turn = (turn + 1) % 2;
+                        monitor.notify();
+                    }
+                }
+            }
+        };
+        t1.setName("T1");
+        t2.setName("T2");
+        t1.start();
+        t2.start();
+        t1.join();
+        t2.join();
+        System.out.println(counter);
+        System.out.println(System.currentTimeMillis() - startTime);
+    }
+}

week6/1-Multithreading/Core_Java_2_week6/src/week6/task2/producer_consumer/ConsumerThread.java

@@ -0,0 +1,17 @@
+package week6.task2.producer_consumer;
+
+
+public class ConsumerThread implements Runnable {
+	private MyBlockingQueue<String> queue;
+
+	public ConsumerThread(MyBlockingQueue<String> queue) {
+		this.queue = queue;
+	}
+
+	@Override
+	public void run() {
+		while (queue.size() > 0) {
+			queue.poll();
+		}
+	}
+}

week6/1-Multithreading/Core_Java_2_week6/src/week6/task2/producer_consumer/ProducerThread.java

@@ -0,0 +1,18 @@
+package week6.task2.producer_consumer;
+
+public class ProducerThread implements Runnable {
+
+	private MyBlockingQueue<String> queue;
+	public ProducerThread(MyBlockingQueue<String> queue) {
+		this.queue = queue;
+
+	}
+
+	@Override
+	public void run() {
+		for (int i = 1; i < 1001; i++) {
+			queue.add(Thread.currentThread().getName() + ": " + i + " - " + System.nanoTime()
+					% 1_000_000);
+		}
+	}
+}

week6/1-Multithreading/Core_Java_2_week6/src/week6/task2/producer_consumer/ThreadRunner.java

@@ -0,0 +1,38 @@
+package week6.task2.producer_consumer;
+
+public class ThreadRunner {
+	public static void main(String[] args) throws InterruptedException {
+		MyBlockingQueue<String> queue = new MyBlockingQueue<>(100);
+
+		ProducerThread p1 = new ProducerThread(queue);
+		ProducerThread p2 = new ProducerThread(queue);
+		ProducerThread p3 = new ProducerThread(queue);
+
+		ConsumerThread c1 = new ConsumerThread(queue);
+		ConsumerThread c2 = new ConsumerThread(queue);
+
+		Thread t1 = new Thread(p1);
+		t1.setName("producer 1");
+		Thread t2 = new Thread(p2);
+		t2.setName("producer 2");
+		Thread t3 = new Thread(p3);
+		t3.setName("producer 3");
+
+		Thread t4 = new Thread(c1);
+		t4.setName("consumer 1");
+		Thread t5 = new Thread(c2);
+		t5.setName("consumer 2");
+
+		t1.start();
+		t2.start();
+		t3.start();
+		t4.start();
+		t5.start();
+//		t1.join();
+//		t2.join();
+//		t3.join();
+//		t4.join();
+//		t5.join();
+
+	}
+}

week8/interviews/OrderTaxProblem/src/Customer.java

@@ -0,0 +1,4 @@
+public class Customer
+{
+    public String StateCode;
+}

week8/interviews/OrderTaxProblem/src/Order.java

@@ -0,0 +1,27 @@
+import java.util.LinkedList;
+import java.util.List;
+
+public class Order
+{
+    public List<OrderItem> orderItems = new LinkedList<OrderItem>();
+    public double CalculateTotal(Customer customer)
+    {
+        double total = 0;
+        for (OrderItem item : orderItems){
+            total += item.Cost*item.Quantity;
+        };
+
+        double tax;
+        if (customer.StateCode == "BUL")
+            tax = total * .2;
+        else if (customer.StateCode == "GER")
+            tax = total * .3;
+        else
+            tax = .1;
+
+        total = total + tax;
+        return total;
+    }
+
+
+}