Google Guava (0)

Google Guava
Margus Martsepp
History
Java collections was created in 1997
3 big  ideas :
• interfaces ( define  collections)
• implementations (concrete or  abstract )
• algorithms (to manipulate collections)
Basic  idea  around this framework :
Extensible - people can  build on it
Overview
1.  Utilities2. Objects {equal, coalesce, ComparisonChain}
3.  Immutable  
Utilities - static constructors
Create a list of 2  elements
Utilities - functional - predicates
Apply predicates on collections/iterables
Functional language  equivalent
Utilities - functional - transform
Create a transformed view of a collection  
Object  
Equals (null safe)
Coalesce
Objects.firstNonNull(obj, default)
 
Object - ComparisonChain
CompareTo  method :
Immutable - why 
Why?
• + Your life is  easy   (no trust problems)
• + Free  thread  safety
• + Can be used as a constant
• + Uses less  memory
• - Rejects null values
Compared to Col ections.unmodifiable?
• - overhead 
• - unsafe 
• - verbose
Immutable - how
Create a set of elements
ImmutableSet.of("a", "b", "c", "a", "d", "b")
Using a builder
public static  final  ImmutableSet GOOGLE_COLORS =
       ImmutableSet.builder()
           .addAll(WEBSAFE_COLORS)
           .add(new  Color (0, 191, 255))
           .build();
Creating a defencive copy
ImmutableList.copyOf(col ection);
Immutable - collections
JDK
Guava
ImmutableCollection
ImmutableMultiset
ImmutableSortedMultiset
ImmutableList
ImmutableMultimap
ImmutableSet
ImmutableListMultimap
ImmutableSortedSet
ImmutableSetMultimap
ImmutableMap
ImmutableBiMap
ImmutableClassToInstanceMap
ImmutableSortedMap
ImmutableTable
Summary
I talked about:
1. }
2. Objects {equal, coalesce, ComparisonChain}
3. Immutable 
The end

Document Outline

• Slide 1
• History
• Overview
• Utilities - static constructors
• Utilities - functional - predicates
• Utilities - functional - transform
<
• Object - ComparisonChain
• Immutable - why 
• Immutable - how
• Immutable - collections
• Summary
• The end