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
   

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2. @ToddGinsberg
   Three New Features
   Coming to Java
   Chicago JUG
   Todd Ginsberg
   Principal Software Developer
   2020-12-10
   2 ½
   

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3. @ToddGinsberg
   1
   

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4. @ToddGinsberg
   @ToddGinsberg
   Syntax - instanceof Pattern Matching
   

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5. @ToddGinsberg
   @ToddGinsberg
   Syntax - instanceof Pattern Matching
   if(someObject instanceof String) {
   String someString = (String)someObject;
   doSomethingWithString(someString);
   }
   

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6. @ToddGinsberg
   @ToddGinsberg
   Syntax - instanceof Pattern Matching
   if(someObject instanceof String someString) {
   doSomethingWithString(someString);
   }
   

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7. @ToddGinsberg
   2
   

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8. @ToddGinsberg
   @ToddGinsberg
   Sealed Types (Preview)
   Have you ever wanted…
   

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9. @ToddGinsberg
   @ToddGinsberg
   Sealed Types (Preview)
   Have you ever wanted…
   ● To limit the implementations of an interface?
   

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10. @ToddGinsberg
    @ToddGinsberg
    Sealed Types (Preview)
    Have you ever wanted…
    ● To limit the implementations of an interface?
    ● Or subclases to your class?
    

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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?
    

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12. @ToddGinsberg
    @ToddGinsberg
    Sealed Types (Preview)
    Neha Sardana
    Will cover this in detail!
    

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13. @ToddGinsberg
    3
    

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14. @ToddGinsberg
    @ToddGinsberg
    Records
    

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15. @ToddGinsberg
    @ToddGinsberg
    Records
    Records are immutable data holders
    

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16. @ToddGinsberg
    @ToddGinsberg
    Records
    If we wanted an immutable 2-D Point we would need to:
    

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17. @ToddGinsberg
    @ToddGinsberg
    Records
    If we wanted an immutable 2-D Point we would need to:
    ● Define a class
    

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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
    

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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
    

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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
    

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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()
    

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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()
    

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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()
    

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24. @ToddGinsberg
    @ToddGinsberg
    Records
    This pattern is VERY common!
    

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25. @ToddGinsberg
    @ToddGinsberg
    Records
    This pattern is VERY common!
    record Point(int x, int y) {}
    

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26. @ToddGinsberg
    @ToddGinsberg
    Records
    This pattern is VERY common!
    record Point(int x, int y) {}
    var point = new Point(1, 2);
    

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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());
    

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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());
    

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29. @ToddGinsberg
    @ToddGinsberg
    Records
    record Point(int x, int y) {
    public Point {
    if(x < 0) throw new IllegalArgumentException();
    if(y < 0) throw new IllegalArgumentException();
    }
    }
    

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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());
    }
    }
    

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31. @ToddGinsberg
    @ToddGinsberg
    Records
    ● Records extend java.lang.Record
    

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32. @ToddGinsberg
    @ToddGinsberg
    Records
    ● Records extend java.lang.Record
    ● Records are final
    

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33. @ToddGinsberg
    @ToddGinsberg
    Records
    ● Records extend java.lang.Record
    ● Records are final
    ● Record fields are final
    

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34. @ToddGinsberg
    @ToddGinsberg
    Records
    ● Records extend java.lang.Record
    ● Records are final
    ● Record fields are final
    ● Cannot define any more fields
    

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35. @ToddGinsberg
    @ToddGinsberg
    Records
    

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36. @ToddGinsberg
    @ToddGinsberg
    Records
    ● Think of every DTO you’ve ever written
    

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37. @ToddGinsberg
    @ToddGinsberg
    Records
    ● Think of every DTO you’ve ever written
    ● Or every Pair class you’ve written
    

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38. @ToddGinsberg
    @ToddGinsberg
    Records
    ● Think of every DTO you’ve ever written
    ● Or every Pair class you’ve written
    ● Or every time you wished you had a better Map key
    

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39. @ToddGinsberg
    @ToddGinsberg
    todd@ginsberg.com
    https://todd.ginsberg.com
    Thank You!
    Anonymous Feedback!
    

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