Following are the new features in SE 6.
Changes in I/O
This is a new feature added in Java SE 6, which has the ability to read text from a terminal without having it echo on the screen through java.io.Console.
Collections Framework Enhancement
In Collection framework, we are able to improve the performance hashing function that is used by java.util.HashMap. It provides some new Collection interfaces also.
Changes in jar and zip
Jar and zip support has been enhanced in JDK 6. In this, two new compressed streams have been added. These are java.util.zip.DeflaterInputStream and java.util.zip.InflaterOutputStream.
Java Web Start enhancements in version 6
The cache format of Java Web Start and Plug-In has been fully changed. All dialogs have been redesigned and consolidated between Java Web Start and Plug-In to be more user friendly.
JMX API Enhancements
Enhancements has been made to the JMX API in Java SE 6 like : JMX API now completely supports Generics, MXBeans have been added and much more?
Java Platform Debugger Architecture Enhancements
JVMDI has been deleted in JAVA SE 6 and JPDA has been added. Some new Methods are included like boolean boolean canGetInstanceInfo() and much more?
Java SE 6 Monitoring and Management Enhancements
API provided by JAVA SE allows you to monitor and manage the JVM in the package java.lang.management. JAVA SE 6 includes some enhancement to this API.
New Package java.util.spi in JDK 6
A new package Java.util.spi has been included in JAVA SE 6.
Networking features and enhancements in Java SE version 6.0
This feature include enhancement in networkInterface, support for Internationalized Domain Names, HTTP Negotiate Authentication and much more?
Enhancements in java.lang.Class and java.lang.reflect
Some new Methods are included in java.lang.Class like : getInterfaces(), getClasses(), getConsturctors(), getMethod(String, Class?) and much more?.
Enhancement in RMI for JDKTM 6
java.rmi.MarshalledObject now support generics
JAVA SE 6 Security Enhancements
JAVA SE 6 has added support for some security functionality: the XML Digital signature API and implementation, Smart Card I/O API. And much more?
Serialization Changes and Enhancements in JAVA SE Development Kit 6
The new method ObjectStreamClass.lookupAny now used to obtain an ObjectStreamClass instance for a non-serializable Class
JavaTM Virtual Machine Technology
DTrace support has include in Java SE 6 HotSpot VM. The hotspot provider makes available probes that can be used to track the lifespan of the VM, thread start and stop events
Scripting for the Java Platform
By using this Features developers integrate Java technology and scripting languages by defining a standard framework and application programming interface (API)
Leveraging Security in the Native Platform Using Java SE 6 Technology
The JAVA SE 6 provide a large set of security APIs. These Security APIs span a wide range of areas, including cryptography public key infrastructure, secure communication, authentication, and access control.
JAX-Web Services 2.0 With the Java SE 6 Platform
Most exciting new features of the JAVA SE 6 is support for the Java API for XML Web Services (JAX-WS), version 2.0.
Recommend the tutorial