Java Collections Framework Overview
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Java Collections Framework Overview

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Questions and Answers

What is the Java collection framework used for?

The Java collections framework gives the programmer access to prepackaged data structures as well as to algorithms for manipulating them.

What is a collection?

A collection is an object that can hold references to other objects.

The classes and interfaces of the collections framework are in which package?

java.util

What are the static methods of class Arrays used for?

<p>Including sort for sorting an array, binary search for searching a sorted array, equals for comparing arrays, and fill for placing items in an array.</p> Signup and view all the answers

What does Arrays method asList return?

<p>A List view of an array.</p> Signup and view all the answers

What does method size do?

<p>Gets the number of items in a List.</p> Signup and view all the answers

What does method get do?

<p>Returns a List element.</p> Signup and view all the answers

What is the root interface in the collection hierarchy?

<p>Interface Collection</p> Signup and view all the answers

What does class Collections provide?

<p>Static methods for manipulating collections.</p> Signup and view all the answers

What is a List?

<p>An ordered Collection that can contain duplicate elements.</p> Signup and view all the answers

Which classes implement the Interface List?

<p>ArrayList, LinkedList, and Vector.</p> Signup and view all the answers

What does Iterator method hasNext do?

<p>Determines whether a Collection contains another element.</p> Signup and view all the answers

What does method subList return?

<p>A view of a portion of a List.</p> Signup and view all the answers

What does method clear do?

<p>Removes elements from a List.</p> Signup and view all the answers

What does method toArray do?

<p>Returns the contents of a collection as an array.</p> Signup and view all the answers

What does class Vector manage?

<p>Dynamically resizable arrays.</p> Signup and view all the answers

What does Vector method add do?

<p>Adds its argument to the end of the Vector.</p> Signup and view all the answers

What does method insertElementAt do?

<p>Inserts an element at the specified position.</p> Signup and view all the answers

What does Vector method remove do?

<p>Removes the first occurrence of its argument from the Vector.</p> Signup and view all the answers

What does method removeAllElements do?

<p>Removes every element from the Vector.</p> Signup and view all the answers

What does Vector method firstElement do?

<p>Returns a reference to the first element.</p> Signup and view all the answers

What does Vector method contains do?

<p>Determines whether the Vector contains the searchKey specified as an argument.</p> Signup and view all the answers

What does Vector method isEmpty do?

<p>Determines whether the Vector is empty.</p> Signup and view all the answers

What does algorithm reverse do?

<p>Reverses the elements of a List.</p> Signup and view all the answers

What does algorithm sort do?

<p>Sorts the elements of a List.</p> Signup and view all the answers

What does algorithm addAll do?

<p>Appends all the elements in an array to a collection.</p> Signup and view all the answers

Study Notes

Java Collections Framework

  • Provides prepackaged data structures and algorithms for manipulating them.
  • Located in the java.util package.

Collections Definition

  • A collection is an object that holds references to other objects.
  • Collection interfaces specify operations for each collection type.

Array Manipulation

  • Static methods in Class Arrays: sort, binarySearch, equals, and fill for array manipulation.
  • Arrays.asList creates a List view of an array, allowing bidirectional changes between the array and the List.

List Interface

  • A List is an ordered collection that allows duplicate elements.
  • Implemented by classes such as ArrayList, LinkedList, and Vector.

Collection Interface

  • The root interface in the collection hierarchy, gives rise to interfaces Set and List.
  • Includes bulk operations like adding, clearing, and retaining objects, along with an iterator method.

Collections Class

  • Provides static methods for collection manipulation, implementing polymorphic algorithms for searching and sorting.

Iterator Method

  • hasNext checks if a collection contains another element.
  • next retrieves and advances to the next object in the collection.

List Modifications

  • clear removes elements from a List.
  • subList provides a view of a portion of a List, where changes reflect in the original List.
  • toArray converts a collection into an array format.

Vector Class

  • Manages dynamically resizable arrays with a default capacity of 10 elements.
  • When growing, it either increments by a specified capacity or doubles its size if none is given.
  • Methods include add for appending elements, remove for deleting occurrences, and removeAllElements for clearing the entire Vector.

Vector Specific Methods

  • firstElement and lastElement return references to the first and last elements, respectively.
  • contains checks if a specified searchKey is present.
  • indexOf retrieves the index of the first occurrence of an element, returning -1 if not found.
  • isEmpty determines if the Vector has any elements.

Algorithms

  • reverse changes the order of List elements.
  • fill alters all elements of a List to a specified object.
  • copy transfers elements from one List to another.
  • sort organizes the List elements in order.
  • addAll appends elements from an array to a collection, while frequency counts occurrences of specified elements in a collection.

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Description

Explore the essential concepts of the Java Collections Framework, including the collection interfaces, array manipulation methods, and the List interface. This quiz will test your knowledge on how these components interact and their significance in Java programming.

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