Three New Features Coming to Java

This is a lightning talk I did for the Chicago Java User Group. Originally it was supposed to be three features, but another speaker was doing a lightning talk on Sealed Types, so I cut most of that. In this talk we mostly discuss instanceof and Java Records

Transcript

1. @ToddGinsberg Three New Features Coming to Java Chicago JUG Todd Ginsberg Principal Software Developer 2020-12-10
2. @ToddGinsberg Three New Features Coming to Java Chicago JUG Todd Ginsberg Principal Software Developer 2020-12-10 2 ½
3. @ToddGinsberg 1
4. @ToddGinsberg @ToddGinsberg Syntax - instanceof Pattern Matching
5. @ToddGinsberg @ToddGinsberg Syntax - instanceof Pattern Matching if(someObject instanceof String) { String someString = (String)someObject; doSomethingWithString(someString); }
6. @ToddGinsberg @ToddGinsberg Syntax - instanceof Pattern Matching if(someObject instanceof String someString) { doSomethingWithString(someString); }
7. @ToddGinsberg 2
8. @ToddGinsberg @ToddGinsberg Sealed Types (Preview) Have you ever wanted…
9. @ToddGinsberg @ToddGinsberg Sealed Types (Preview) Have you ever wanted… • To limit the implementations of an interface?
10. @ToddGinsberg @ToddGinsberg Sealed Types (Preview) Have you ever wanted… • To limit the implementations of an interface? • Or subclases to your class?
11. @ToddGinsberg @ToddGinsberg Sealed Types (Preview) Have you ever wanted… • To limit the implementations of an interface? • Or subclases to your class? • Without having to do wacky things with enums?
12. @ToddGinsberg @ToddGinsberg Sealed Types (Preview) Neha Sardana Will cover this in detail!
13. @ToddGinsberg 3
14. @ToddGinsberg @ToddGinsberg Records
15. @ToddGinsberg @ToddGinsberg Records Records are immutable data holders
16. @ToddGinsberg @ToddGinsberg Records If we wanted an immutable 2-D Point we would need to:
17. @ToddGinsberg @ToddGinsberg Records If we wanted an immutable 2-D Point we would need to: • Define a class
18. @ToddGinsberg @ToddGinsberg Records If we wanted an immutable 2-D Point we would need to: • Define a class • With two fields called x and y
19. @ToddGinsberg @ToddGinsberg Records If we wanted an immutable 2-D Point we would need to: • Define a class • With two fields called x and y • And an all-arguments constructor
20. @ToddGinsberg @ToddGinsberg Records If we wanted an immutable 2-D Point we would need to: • Define a class • With two fields called x and y • And an all-arguments constructor • And getters
21. @ToddGinsberg @ToddGinsberg Records If we wanted an immutable 2-D Point we would need to: • Define a class • With two fields called x and y • And an all-arguments constructor • And getters • And equals()
22. @ToddGinsberg @ToddGinsberg Records If we wanted an immutable 2-D Point we would need to: • Define a class • With two fields called x and y • And an all-arguments constructor • And getters • And equals() • And hashcode()
23. @ToddGinsberg @ToddGinsberg Records If we wanted an immutable 2-D Point we would need to: • Define a class • With two fields called x and y • And an all-arguments constructor • And getters • And equals() • And hashcode() • And toString()
24. @ToddGinsberg @ToddGinsberg Records This pattern is VERY common!
25. @ToddGinsberg @ToddGinsberg Records This pattern is VERY common! record Point(int x, int y) {}
26. @ToddGinsberg @ToddGinsberg Records This pattern is VERY common! record Point(int x, int y) {} var point = new Point(1, 2);
27. @ToddGinsberg @ToddGinsberg Records This pattern is VERY common! record Point(int x, int y) {} var point = new Point(1, 2); System.out.println("X: " + point.x()); System.out.println("Y: " + point.y());
28. @ToddGinsberg @ToddGinsberg Records This pattern is VERY common! record Point(int x, int y) {} var point = new Point(1, 2); System.out.println("X: " + point.x()); System.out.println("Y: " + point.y());
29. @ToddGinsberg @ToddGinsberg Records record Point(int x, int y) { public Point { if(x < 0) throw new IllegalArgumentException(); if(y < 0) throw new IllegalArgumentException(); } }
30. @ToddGinsberg @ToddGinsberg Records record Point(int x, int y) { public Point { if(x < 0) throw new IllegalArgumentException(); if(y < 0) throw new IllegalArgumentException(); } public Point(Point3D other) { this(other.x(), other.y()); } }
31. @ToddGinsberg @ToddGinsberg Records • Records extend java.lang.Record
32. @ToddGinsberg @ToddGinsberg Records • Records extend java.lang.Record • Records are final
33. @ToddGinsberg @ToddGinsberg Records • Records extend java.lang.Record • Records are final • Record fields are final
34. @ToddGinsberg @ToddGinsberg Records • Records extend java.lang.Record • Records are final • Record fields are final • Cannot define any more fields
35. @ToddGinsberg @ToddGinsberg Records
36. @ToddGinsberg @ToddGinsberg Records • Think of every DTO you’ve ever written
37. @ToddGinsberg @ToddGinsberg Records • Think of every DTO you’ve ever written • Or every Pair<A,B> class you’ve written
38. @ToddGinsberg @ToddGinsberg Records • Think of every DTO you’ve ever written • Or every Pair<A,B> class you’ve written • Or every time you wished you had a better Map key
39. @ToddGinsberg @ToddGinsberg todd@ginsberg.com https://todd.ginsberg.com Thank You! Anonymous Feedback!