Refactoring to Java X

Transcription

1 Refactoring to Java X

2 Refactoring to Java X

3 Reinier Zwitserloot Roel Spilker

4 The boilerplate busters

5 Java X The new language features Feature I Feature II Feature III Feature IV

6 Java X The new language features Feature I Feature II Feature III Feature IV Feature V Feature VI Feature VII Feature VIII Feature IX Feature X Feature XI Feature XII Feature XIII Feature XIV Feature XV Feature XVI Feature XVII Feature XVIII Feature XIX Feature XX

7 Java X The new language features Feature I: var x = 10; Feature II Feature III Feature IV Feature V Feature VI Feature VII Feature VIII Feature IX Feature X Feature XI Feature XII Feature XIII Feature XIV Feature XV Feature XVI Feature XVII Feature XVIII Feature XIX Feature XX

8

9 C XC VI : The first release

10 1997 C XC C V XC I: 1.0 VI I: 1.1 Language: Nested classes Reflection Java I API: JavaBeans JDBC Internationalization

11 1998 C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 Language: strictfp Java II API: Swing Corba The collections API

12 C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : Language: Java III API:

13 2000 Java III Language: API: C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 Let s forget about this one

14 2002 C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 Language: assert Java IV API: Regexps exception cause IPv6 Non-blocking I/O XL parser java.util.logging Crypto: JCE, JSSE, JAAS JPG and PNG reading Preferences API

15 2004 Java V C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 Language: Generics autobox/unbox varargs enums foreach annotations API: genericsified core lib java.util.concurrent

16 2006 Java VI C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI :6 Language: auto-discovered annotations... API: Rhino (scripting langs) JAX-WS Compiler API SwingWorker Speed improvements

17 :7 XI C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI : Java VII

18 :7 XI C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI : Java VII

19 Java VII XI :7 API: java.nio.file C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI :6 Language: try with resources strings in switch Diamond operator binary literals ulti-catch 2011

20 Java VIII V: XI XI :7 8 API: java.time (joda/jsr310) Lambda-fication of core streams C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI :6 Language: Lambdas default methods Static methods in interfaces 2014

21 II: XV V: XI :7 XI 9 8 Language: odules (jigsaw) C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI : Java IX API:

22 8 X XVII: XVIII: 9 XVIII: 10 IX 11 XI : 12 X: 13 V: XI :7 XI C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI :6 The future X: arch 2018 XI: September 2018 XII: arch 2019 XIII: September

23 Java VIII X XVII: XVIII: 9 XVIII: 10 IX 11 XI : 12 X: 13 V: XI XI :7 8 API: java.time (joda/jsr310) Lambda-fication of core streams C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI :6 Language: Lambdas default methods Static methods in interfaces 2014

24 Java VIII X XVII: XVIII: 9 XVIII: 10 IX 11 XI : 12 X: 13 V: XI XI :7 8 API: java.time (joda/jsr310) Lambda-fication of core streams C XC C V I XC : 1.0 C VI XC I: 1.1 VI II: 1.2 : 1. 3 II: 1.4 IV :5.0 VI :6 Language: Lambdas default methods Static methods in interfaces Repeatable annotations 2014

25 Where did we get these from? JDK Enhancement Proposals (JEPs) Presentations by Brian Goetz, ark Reinhold Conferences OpenJDK mailing lists and hg commit traffic

26 VAR

27 Java I Vector names = new Vector();

28 Java II-IV List names = new ArrayList();

29 Java V List<String> names = new ArrayList<String>();

30 Java V Guava List<String> names = Lists.newArrayList();

31 Java VI-IX List<String> names = new ArrayList<>();

32 Java X var names = new ArrayList<String>();

33 var? var name = "FOO"; name = name.tolowercase(); name = name.subsequence(0, 1); CharSequence! or... String?

34 var? var name = "FOO"; name = name.tolowercase(); name = name.subsequence(0, 1);

35 var? var name = "FOO"; String!

36 Java VI-X Lombok val names = new ArrayList<String>(); var names = new ArrayList<String>();

37

38 8000 bytes int x, y; X Y X X X Y Y X Y Y X X Y X Y Y X Y X Y

39 public class Point { int x, y; } 8000 bytes Point[] p = new Point[1000];

40 public class Point { int x, y; } 8000 bytes bytes bytes Point[] p = new Point[1000]; X X Y X Y X Y X Y Y X X Y Y X Y X X Y Y

41 public class Point { int x, y; } 8000 bytes int[] p = new int[2000]; X Y X Y X Y X Y X Y X Y X Y X Y X Y X Y

42 public class Point { int x, y, z; double luminance; }

43 public struct Point { int x, y; } 8000 bytes Point[] p = new Point[1000]; X Y X Y X Y X Y X Y X Y X Y Performs like an int! X Y X Y X Y

44 public struct Point { int x, y; } 8000 bytes public double vectorlength() { return ath.sqrt(x*x + y*y); } Codes like a class!

45 Not a reference public class Foo { private Point p; } What is the value of p?

46 Not a reference public class Foo { private Point p; } p will be: Point(0, 0);

47 No Object Identity No: synchronized(point) point.wait() point.notify() point.notifyall() point.finalize()

48 Generics new ArrayList<String>(); new ArrayList<Point>(); new ArrayList<int>();

49 Generics new ArrayList<int>(); public class ArrayList<T> { Object[] elementdata; }

50 Generics new ArrayList<int>(); public class ArrayList<T> { int[] elementdata; } The <int> specialization

51 Not subtype of Object List<?> x = new ArrayList<int>();

52 Not subtype of Object List<? extends Object> x = new ArrayList<int>();

53 Not subtype of Object List<? extends Object> x = new ArrayList<int>();... but int does not extend object! Object obj = x.get(0);

54 Not subtype of Object List<? extends Object> x = new ArrayList<int>(); autoboxing! Object obj = x.get(0); obj is a java.lang.integer

55 Not subtype of Object List<?> x = new ArrayList<Point>(); Object obj = x.get(0); valhalla types are their own boxed type.

56 Generics + valhalla Autoboxing Generics specialization

57 equals, hashcode, and tostring Default impl unsuitable: equals() hashcode() new Point(0, 0).equals( new Point(0, 0)); t u o g h t i tin lf! w n rse t e o N plem you im als u eq

58 equals, hashcode, and tostring Default impl unsuitable: tostring()

59 equals, hashcode, and tostring Default impl unsuitable: tostring() Point(x=0, y=0) t u o g! h f t l i n i se w t r n t e you o m N ple g n i m i Str to

60 public class Point { private final int x, y; public Point(int x, int y) { this.x = x; this.y = y; } public int getx() { return x; } public int gety() { return y; public String tostring() { return "Point(x=" + x + ", y=" + y + ");"; public boolean equals(object other) {... public int hashcode() {... } }

61 public struct Point { int x, y; }

62 public struct Point { int x, y; } field-based: equals() hashcode() tostring() constructor

63 public struct Point { int x, y; } public value class Point { int x, y; }

64 class Point { int x, y; }

65 Lombok class Country { String name; List<String> cities; }

66 Lombok feature Country.builder().name("Germany").cities(ImmutableList.of( "Saarbrücken", "annheim", "Kaiserslautern", "Darmstadt")).build();

67 Lombok feature Country.builder().name("Germany").cities(ImmutableList.of( "Saarbrücken", "annheim", "Kaiserslautern", "Darmstadt")).build();

68 Lombok feature Country.builder().name("Germany").city("Saarbrücken").city("annheim").city("Kaiserslautern").city("Darmstadt").build();

69 Lombok class Country { String List<String> cities; }

70 Valhalla: I. II. III. IV. ake-your-own-primitives: Valhalla types Generics specialization: new ArrayList<int>() Autoboxing valhalla types field-based constructor, equals, tostring ake more types!!

71 Lombok: I. II. III. IV. V. ake-your-own-primitives: Valhalla types Generics specialization: new ArrayList<int>() Autoboxing valhalla types field-based constructor, equals, tostring Builders

72

73

74 double length(object obj) { if (obj instanceof Number) { Number number = (Number) obj; return ath.abs(number.doublevalue()); } else if (obj instanceof ComplexNumber) { ComplexNumber complexnumber = (ComplexNumber) obj; return complexnumber.length(); } throw new UnsupportedOperationException(); }

75 double length(object obj) { if (obj instanceof Number) { Number number = (Number) obj; return ath.abs(number.doublevalue()); } else if (obj instanceof ComplexNumber) { ComplexNumber complexnumber = (ComplexNumber) obj; return complexnumber.length(); } throw new UnsupportedOperationException(); }

76 double length(object obj) { if (obj instanceof Number number) { return ath.abs(number.doublevalue()); } else if (obj instanceof ComplexNumber complexnumber) { return complexnumber.length(); } throw new UnsupportedOperationException(); }

77 double length(object obj) { switch (obj) { case Number number: return ath.abs(number.doublevalue()); case ComplexNumber complexnumber: return complexnumber.length(); } default: throw new UnsupportedOperationException(); }

78 double length(object obj) { switch (obj) { case Number number: return ath.abs(number.doublevalue()); case ComplexNumber complexnumber: return complexnumber.length(); } default: throw new UnsupportedOperationException(); }

79 double length(object obj) { return switch (obj) { case Number number -> ath.abs(number.doublevalue()); case ComplexNumber complexnumber -> complexnumber.length(); } default: throw new UnsupportedOperationException(); }

80 Refactoring to Java X 1. Use val / var 2. ake more types (@Value) 3. Review your visitors APIs

81 Refactoring to Java X 1. Use val / var 2. ake more types (@Value) 3. Review your visitors APIs