1. Advanced Programming in Java
Salman Marvasti
Sharif University of Technology
Fall 2015

2. Review Java Programming Language
Principles of Object Oriented Programming
Characteristics of objects
Encapsulation
Objects in memory
References
Heap
Stack
Parameter Passing
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3. Review (2) Initialization and Cleanup Access specifiers Constructor
finalize()
Order of initialization
Initialization blocks
Access specifiers
Public
Private
Package access
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4. Review (3) Package Static The this reference Method overloading
toString()
equals()
Polymorphism
Overriding , Upcasting
Interface
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5. Agenda Software Quality Characteristic of a good software Test
Unit Testing
Refactoring
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6. Quality of Product
The producer should ensure about the quality of the products
Quality Control
Any business, any product
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7. A Cook
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8. In surgery
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9. A Car Maker
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10. Quality Control Quality should be tested
A product is not finalized, before the test
Different kinds of test, check different kinds of quality
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11. Software Quality We are programmers Programmers produce software
What are characteristics of a good software?
Many parameters. E.g.
Conformance to requirements
Performance
Time
Memory
Maintainability
Changeability
Different kinds of test, check different kinds of quality
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12. Test in Other Industries
Test side effects
A damage to the product
Test of a building
Test of a car
Test of a part of a product
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13. Test Side Effects
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14. What to do with Test Side Effects?
Testing a sample of the product
Simulation
Mathematical analysis
In software testing
Along with all of these techniques
And we can also test the software itself!
(Usually) no damage to the software
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15. Test Target System Test Unit Test Test the system as a whole
For performance, correctness and conformance.
Unit Test
Test the units and modules
Test of a component
Test of a class
Test of a method
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16. How to Test Software Manual Test Test Tools Test Code Test Teams
Try it!
Test Tools
Performance Test
Profiling
JProfiler, TPTP
Load Test
Jmeter
Test Code
Unit Tests
Test Teams
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17. Test Code Business Code Test Code
The code, written for implementation of a requirement
Test Code
The code, written for test of an implementation
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18. Unit Testing A process for the programmer Test of units of software
Not a test team procedure
For improving the code quality
Reduces bugs
Test of units of software
before the software is completed
Unit: method, class
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19. Classical Unit Testing
Writing main() method
Some printlns
Drawbacks?
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20. Drawbacks Test code coupled with business code
In the same class
Written tests are discarded
One test at a time
The programmer executes the tests himself
Test execution is not automatic
The programmer should check the result of each test himself
The test is passed or failed?
The test result interpretation is not automatic
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21. A Good Unit Test Code Repeatable Automatic
Invocation
Acceptance (Pass/Failure)
JUnit helps you write such tests
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22. JUnit, First Example
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23. JUnit, The Green Bar
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24. public class Testing public void testNormal() { int[] array = {3,2,1,4}; int[] sorted = {1,2,3,4}; Business.sort(array); for (int i = 0; i < sorted.length; i++) { Assert.assertEquals(sorted[i], array[i]); } public void testEmptyArray() { int[] array = {}; try{ }catch(Exception e){ Assert.fail(); Assert.assertNotNull(array); Assert.assertEquals(array.length, 0);
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25. Assertions assertNull(x) assertNotNull(x) assertTrue(boolean x)
assertFalse(boolean x)
assertEquals(x, y)
Uses x.equals(y)
assertSame(x, y)
Uses x ==y
assertNotSame
fail()
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26. Annotations @Test @Before @After @BeforeClass @AfterClass
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27. Sharif University of Technology

28. A Good Unit Test is Automated Through Repeatable Independence
Professional
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29. Test Driven Development
Test First Development
Before writing a code, write the tests!
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30. TDD
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31. Refactoring

32. Refactoring
A disciplined way to restructure code
In order to improve code quality
Without changing its behavior
a change made to the internal structure of software to make it easier to understand and cheaper to modify without changing its observable behavior.
Martin Fowler
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33. Refactoring Refactoring is the process of changing a software system
In such a way that it does not alter the external behavior of the code
But improves its internal structure
It is a disciplined way to clean up code
It minimizes the chances of introducing bugs
When you refactor, you are improving the design of the code after it has been written.
Martin Fowler
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34. Refactoring
By continuously improving the design of code, we make it easier and easier to work with
Joshua Kerievsky, Refactoring to Patterns
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35. Example Duplicate Code What are the drawbacks? What is the solution?
Refactoring:
Finding a “Bad Smell”
Changing the code to remove the bad smell
Some well-known bad smells are reported
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36. Bad Smell A bad smell in code
Any symptom in the source code that possibly indicates a deeper problem.
The term is coined by Kent Beck.
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37. Bad Smells If it stinks, change it! Bad smells in code
Kent Beck and Martin Fowler.
Bad smells in code
Bad smells are source of problems
Remove bad smells
How?
By Refactoring
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38. Bad Smells Duplicated Code Long Method Large Class Long Parameter List…
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39. Refactoring Techniques
Extract Method
Move
Method
Variable
Class
Extract Class
Rename
Pull Up
Push Down
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40. IDE Support Refactoring techniques are widely supported by IDEs
Practice it in Eclipse
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41. The Two Hats Kent Beck's metaphor of two hats
Divide your time between two distinct activities
adding function
refactoring
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42. Why Should I Refactor? Refactoring Improves the Design of Software
Refactoring Makes Software Easier to Understand
Refactoring Helps You Find Bugs
Refactoring Helps You Program Faster
Refactoring makes your code more maintainable
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43. When Should You Refactor?
The Rule of Three:
Refactor When You Add Function
Refactor When You Need to Fix a Bug
Refactor As You Do a Code Review
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44. Find bad smells! Refactor the Code!
Scanner s = new Scanner(System.in); System.out.println("Rectangle Info."); System.out.print("Enter the width: "); int a1 = s.nextInt(); System.out.print("Enter the length: "); int a2 = s.nextInt(); int b1 = s.nextInt(); int b2 = s.nextInt(); int x = a1*a2; int y = b1*b2; if(x == y) System.out.println("Equal");
Find bad smells!
Refactor the Code!
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45. Scanner scanner = new Scanner(System. in); System. out
Scanner scanner = new Scanner(System.in); System.out.println("Rectangle Info."); System.out.print("Enter the width: "); int width1 = scanner.nextInt(); System.out.print("Enter the length: "); int length1 = scanner.nextInt(); int width2 = scanner.nextInt(); int length2 = scanner.nextInt(); int area1 = width1*length1; int area2 = width2*length2; if(area1 == area2) System.out.println("Equal");
Rename…
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46. class Rectangle{ private int length , width; public int getLength() { return length; } public void setLength(int length) { this.length = length; public int getWidth() { return width; public void setWidth(int width) { this.width = width; public Rectangle(int length, int width) {
Extract Class…
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47. Scanner scanner = new Scanner(System. in); System. out
Scanner scanner = new Scanner(System.in); System.out.println("Rectangle Info."); System.out.print("Enter the width: "); int width = scanner.nextInt(); System.out.print("Enter the length: "); int length = scanner.nextInt(); Rectangle rectangle1 = new Rectangle(length, width); width = scanner.nextInt(); length = scanner.nextInt(); Rectangle rectangle2 = new Rectangle(length, width); int area1 = rectangle1.getWidth()*rectangle1.getLength(); int area2 = rectangle2.getWidth()*rectangle2.getLength(); if(area1 == area2) System.out.println("Equal");
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48. int area1 = rectangle1.area(); int area2 = rectangle2.area();
class Rectangle{
...
public int area(){
return length * width; } …
int area1 = rectangle1.area();
int area2 = rectangle2.area();
Extract Method…
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49. private static Rectangle readRectangle(Scanner scanner) { int width; int length; System.out.println("Rectangle Info."); System.out.print("Enter the width: "); width = scanner.nextInt(); System.out.print("Enter the length: "); length = scanner.nextInt(); Rectangle rectangle2 = new Rectangle(length, width); return rectangle2; }
Extract Method…
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50. Refactored Code
Scanner scanner = new Scanner(System.in); Rectangle rectangle1 = Rectangle.readRectangle(scanner); Rectangle rectangle2 = Rectangle.readRectangle(scanner); int area1 = rectangle1.area(); int area2 = rectangle2.area(); if(area1 == area2) System.out.println("Equal");
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51. Reference
Refactoring: improving the design of existing code, Martin Fowler, Kent Beck, John Brant, William Opdyke, Don Roberts (1999)
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52. Additional Info for Bulk Test and Bulk Data Operations – ONLY JAVA 1.8
List<String> names = Arrays.asList("Smith", "Adams", "Crawford"); List<Person> people = peopleDAO.find("London");   // Using anyMatch and method reference List<Person> anyMatch = people.stream().filter(p -> (names.stream().anyMatch(p.name::contains))).
collect(Collectors.toList());   // Using reduce List<Person> reduced = people.stream().
filter(p -> names.stream().reduce(false, (Boolean b, String keyword) -> b || 
p.name.contains(keyword), (l, r) -> l | r)).collect(Collectors.toList());
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