(1)Generics:Provides compile-time (static) type safety for 
collections and eliminates the need for most typecasts 
(type conversion). (Specified by JSR 14.)
 
(2)Metadata: Also called annotations, allows language 
constructs such as classes and methods to be tagged with 
additional data, which can then be processed by metadata-
aware utilities. (Specified by JSR 175.) 

(3)Autoboxing/unboxing: Automatic conversions between 
primitive types (such as int) and primitive wrapper classes 
(such as Integer). (Specified by JSR 201.)
 
(4)Enumerations: The enum keyword creates a typesafe, 
ordered list of values (such as Day.MONDAY, Day.TUESDAY, 
etc.). Previously this could only be achieved by non-
typesafe constant integers or manually constructed classes 
(typesafe enum pattern). (Specified by JSR 201.) 

(5)Swing: New skinnable look and feel, called synth. 
Varargs: The last parameter of a method can now be declared 
using a type name followed by three dots (e.g. void drawtext
(String... lines)). In the calling code any number of 
parameters of that type can be used and they are then 
placed in an array to be passed to the method, or 
alternatively the calling code can pass an array of that 
type. 

(5)Enhanced 'for loop': The for loop syntax is extended 
with special syntax for iterating over each member of 
either an array or any Iterable..

it provides the working facilities like 
applications,applets and core java based programs