What is the difference between ArrayList and Vector?

ArrayList	Vector
It is not synchronized	Vector is synchronized
In case of single thread, ArrayList is faster than Vector	In case of multiple threads, Vector is advisable, with single thread model Vector becomes slow
ArrayList increases it’s size by half every time	Vector increase it’s size double

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.