twitterMappingLab/SentimentDictionary.java at master · NNHSComputerScience/twitterMappingLab · GitHub

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importjava.io.File;
importjava.io.FileNotFoundException;
importjava.util.HashMap;
importjava.util.Map;
importjava.util.Scanner;


/**
 * This class is a singleton that manages access to the sentiments dictionary.
 *
 * The sentiments file is part of the Twitter Trends project by Aditi Muralidharan,
 * John DeNero, and Hamilton Nguyen and featured on Stanford’s Nifty Lab's site.
 *
 * <http://nifty.stanford.edu/2013/denero-muralidharan-trends/>
 *
 * @author gcschmit
 * @version 08jul2016
 */

publicclassSentimentDictionary
{
privatestaticSentimentDictionarysingleton;

privatestaticStringSENTIMENTS_FILENAME = "sentiments.csv";

privateMap<String, Double> dictionary;

/**
 * Default Constructor for objects of class SentimentDictionary.
 *
 * This is private to ensure that the getSingleton method is used by clients.
 */
privateSentimentDictionary()
 {
 }

/**
 * Constructor for objects of class SentimentDictionary.
 *
 * This is private to ensure that the getSingleton method is used by clients.
 *
 * @param fileName name of the sentiments file from which to build this dictionary
 *
 * @precondition the specified file must be a CSV file with two columns.
 * The first contains the word; the second, a sentiment score.
 * The sentiment will range from -1 to 1, where negative values correspond
 * to negative sentiment; positive values, positive.
 */
privateSentimentDictionary( StringfileName )
 {
dictionary = newHashMap<String, Double>();

try
 {
FilesentimentFile = newFile( fileName );
Scannerin = newScanner( sentimentFile );
in.useDelimiter( "[,\r\n]" );

while( in.hasNext())
 {
Stringword = in.next();
Doublesentiment = in.nextDouble();
dictionary.put( word, sentiment );
in.nextLine();
 }

in.close();
 }
catch( FileNotFoundExceptione )
 {
System.out.println( "Sentiment file: " + fileName + " not found." );
 }

 }

/**
 * Returns the singleton instance of the SentimentDictionary.
 * Clients should invoke this method to obtain a refernece to a SentimentDictionary object.
 *
 * @return the singleton instance of the SentimentDictionary
 *
 * @precondition callers are responsible for invoking this method in a thread-safe manner
 */
publicstaticSentimentDictionarygetSingleton()
 {
// not thread safe
if( singleton == null )
 {
singleton = newSentimentDictionary( SENTIMENTS_FILENAME );
 }

returnsingleton;
 }

/**
 * Returns the sentiment associated with the specified word.
 * The sentiment will range from -1 to 1, where negative values correspond
 * to negative sentiment; positive values, positive. If there is no sentiment for
 * the specified word, a null value will be returned.
 *
 * @param word the word whose sentiment will be returned, the word must be all lowercase
 * @return the sentiment associated with the specified word or null if none
 */
publicDoublegetSentiment( Stringword )
 {
returndictionary.get( word );
 }
}