Good Code

The presentation I made for software engineering course @{Bogazici University}

Transcript

1. Barış Evrim Demiröz software engineering @boun 21.11.2013
6. // increments i by one i++;
7. itemCount++;
10. • Function/Variable naming • Code style – Java conventions (Eclipse CTRL+ALT+F) – Google conventions coming soon!
12. x = a*b;
13. salary = hoursWorked*rate;
15. *:execute perform do carry fulfill accomplish
21. if (items.size() < 30)
22. if (items.size() < MAX_ITEMS_ALLOWED)
24. line.split(",");
25. line.split(DELIMITER);
26. line.split(DELIMITER);
35. • Should be simple • Should be fast
36. private void testNoCookie( Cookie[] cookies ) { when( request.getCookies() ).thenReturn( cookies ); CookieHandler handler = new CookieHandler( request ); assertFalse( handler.hasCookie() ); handler.createOrRenew( response ); assertTrue( handler.hasCookie() ); assertTrue( handler.getUUID().length() > 0 ); }
37. @Test public void testNoCookie1() { testNoCookie( null ); } @Test public void testNoCookie2() { testNoCookie( new Cookie[] {} ); }
39. public void testAdd() { assertEquals(3, calculator.add(2, 1)); assertEquals(2, calculator.add(2, 0)); assertEquals(1, calculator.add(2, -1)); }
40. public class Calculator { public int add(int a, int b) { return a + b; } }
41. public class Calculator { private AdderFactory adderFactory; public Calculator(AdderFactor adderFactory) { this.adderFactory = adderFactory; } public int add(int a, int b) { Adder adder = adderFactory.createAdder(); ReturnValue returnValue = adder.compute(new Number(a), new Number(b)); return returnValue.convertToInteger(); } }
42. SO • others • blogs • twitter
50. double calculate(Context foo) { checkNotNull(foo); // rest of the computation… }
53. List<Integer> numbers = asList(1, 2, 3, 4, 5, 6); numbers.forEach(System.out::println);
54. sumAll(numbers, n -> n % 2 == 0);
75. double calculate(int foo) { if (foo < 0) return 0; // rest of the computation… }
76. You Ain’t Gonna Need It
83. public class LongDivision { private static final long MILLIS_PER_DAY = 24 * 60 * 60 * 1000; private static final long MICROS_PER_DAY = 24 * 60 * 60 * 1000 * 1000; public static void main(String[] args) { System.out.println(MICROS_PER_DAY / MILLIS_PER_DAY); } }
84. public class LongDivision { private static final long MILLIS_PER_DAY = 24 * 60 * 60 * 1000; private static final long MICROS_PER_DAY = 24 * 60 * 60 * 1000 * 1000; public static void main(String[] args) { System.out.println(MICROS_PER_DAY / MILLIS_PER_DAY); } }
85. public class LongDivision { private static final long MILLIS_PER_DAY = 24 * 60 * 60 * 1000; private static final long MICROS_PER_DAY = 24 * 60 * 60 * 1000 * 1000; public static void main(String[] args) { System.out.println(MICROS_PER_DAY / MILLIS_PER_DAY); } } overflows
86. public class LongDivision { private static final long MILLIS_PER_DAY = 24L * 60 * 60 * 1000; private static final long MICROS_PER_DAY = 24L * 60 * 60 * 1000 * 1000; public static void main(String[] args) { System.out.println(MICROS_PER_DAY / MILLIS_PER_DAY); } }
88. Don’t hold all the complexity in your mind