Java Collection

What is a collection in java

A collection is an object that groups one or more than one element into a single unit. Collection framework provides interfaces and classes to store, retrieve and manipulate the data.

A collection framework contains interfaces, implementations and classes

• interfaces -Interfaces allow collections to be manipulated independently of the details of their representation
• implementations– These are reusable data structures.

Benefit of using collection:-

• We can add any objects to the collection.
• We can remove any objects from the collection.
• We can identify an object or group of objects from the collection.
• We can iterate/loop through the entire collection using utility classes.

Followings are the some list of Collection classes in Java:

• List
  • Vector in Java
  • ArrayList in Java
  • LinkedList in Java
• Set
  • Hashset in Java
  • Linkedhashset in Java
  • Treeset in Java
• Map
  • Hashmap in Java
  • LinkedHashmap in Java
  • Treemap in Java

For sorting of collection use following interfaces:

• Comparator in Java
• Comparable in Java

Apart from above topic there are some interesting fact about Java Collection:

• How HashMap works internally in Java (Most frequent ask interview question in Java).
• How HashSet works internally in Java.
• Custom key in Hashmap.
• How to create custom Hashset in Java
• What is fail fast and fail safe example in java
• Unmodifiable List in Java or read-only list in Java.

We are still working on more Java collection interview questions.