Brief introduction to Java for complete beginners offered at the London Java Community

1. @AbrahamMarin
Data types and flow control
Abraham Marin-Perez
●Java Programmer for about 10 years
●Also C#, PHP and some Ruby
●Public speaker
●Author

2. Before we start...

3. Data Types

4. Data Types
●Largely, two groups:
– Primitives
– Objects

5. Data Types
●Primitives: simple entities, can be assigned with
literals
●Objects: complex entities, can hold variables
(primitives or other objects) and have functions

6. Data Types
●Primitives: 8 of them
– char
– short
– int
– long
– float
– double
– boolean
– byte

7. Data Types
●Primitives: 8 of them
– char (16-bit Unicode)
– short (32767)
– int (231-1)
– long (263-1)
– float (32-bit)
– double (64-bit)
– boolean (true, false)
– byte (127)

8. Data Types
●Objects: 4000+
●And you can define your own!

9. Data Types
●Three more subtypes:
– Arrays
– Enums
– Interfaces

10. Data Types
●Arrays: a “holder” for a number of instances of a
type
– int[]
– String[]
●It also has methods and properties

11. Data Types
●Enums: enumerations, only a predefined list of
values are valid
Enum Colour {
RED, BLUE, GREEN
}
Colour colour = Colour.GREEN;

12. Data Types
●Interfaces: a “template” for other types

13. Data Types
●Primitives: the same individual value cannot be
shared, a copy is made on assignment
●Objects: multiple references to the same value are
possible, the same value is shared on assignment

14. Data Types
DEMO

15. Flow Control
●The usual suspects:
– if … else
– switch
– while
– do … while
– for
– for (iterable version)

16. Flow Control
DEMO

17. Flow Control - Functional Style
●Available since Java 8

18. Flow Control - Functional Style
DEMO

19. @AbrahamMarin