What is the difference between Iterator and Enumeration?

Iterator	Enumeration
It is useful to retrieve object From a collection	It’s also useful to retrieve object From a collection
Iterator has methods whose Names are easy to follow	Enumeration has methods whose Names are difficult to remember
Iterator has an option to remove Objects from a collection	Which is not available
So Iterator is preferred than Enumeration

What is the difference between Iterator and ListIterator?

• Both are useful to retrieve elements from a collection.
• Iterator can retrieve the elements only in forward direction.
• But ListIterator can retrieve the elements in forward and backward direction also.
• So ListIterator is preferred than Iterator

What is map in collection framework?

• Maps stored elements in the form of key and value pairs.
• If key is provided then its corresponding value can be obtained.
• Of course key should have unique values.

What is a queue in collections framework?

• A queue represents arrangements of elements in FIFO(Firs In First Out) order.
• This means that element that is stored as a first element into the queue will be removed first from the queue.

What is lists in collection framework?

• Lists are like Sets.
• They store a group of elements,
• But Lists allow duplicate values to be stored.

What is a set?

• A set represents a group of elements arranged just like an array.
• The set will grow dynamically when the elements are stored into it.
• A set will not allow duplicate elements.
• If we try to pass same element that is already available in the set, then it is not stored into it.
• Set will not maintain the same order of elements as in which they were entered.

What is the differences between Java5 and Java6?

JAVA-5	JAVA-6
Also known as  Tiger	Also known as  Mustang
Generics—Provides compile-time type safety for collections and eliminates the need for casting every time you get an object out of Collections.  Enhanced For loop—Eliminates error-proneness of iterators. Autoboxing/unboxing—Eliminates need of manual conversion between primitive types (such as double) and wrapper types (such as Double). Typesafe enums—Provides all benefits of the Typesafe enum pattern. Static import—Eliminates the need for using class names prior to using the static member variables of other classes. This will make the code a bit neater. Metadata—Allows  programmers to avoid writing boiler plate code and gives the opportunity for declarative programming.	Annotation Processing API (JSR 269) Common Annotations (JSR 250) Java API for XML Based Web Services - 2.0 (JSR 224)      JAXB 2.0 (JSR 222) Web Services Metadata (JSR 181) Streaming API for XML (JSR 173) XML Digital Signature (JSR 105) Java Class File Specification Update (JSR 202) Java Compiler API (JSR 199) JDBC 4.0 (JSR 221) Scripting in the Java Platform (JSR 223)