Generating Test data

package com.notessensei.randomdata ;

import java.io.InputStream ;
import java.io.InputStreamReader ;
import java.io.OutputStream ;
import java.io.PrintWriter ;
import java.util.Date ;
import java.util.HashMap ;
import java.util.List ;
import java.util.Map ;
import java.util.Random ;

import org.joda.time.DateTime ;

import com.google.gson.Gson ;

import de.svenjacobs.loremipsum.LoremIpsum ;

/**
 * Source of random data to generate test data for anything before use you need
 * either load lists of your data using addRandomStringSource or load a JSON
 * file from a previous run using loadDataFromJson
 *
 * @author NotesSensei
 *
 */
public class RandomLoader {

    /*
     * How often should the random generator try for getRandomString with
     * exclusion before it gives up
     */
    public static final int             MAX_RANDOM_TRIES    = 100 ;
    private Map < String, List < String >>   randomStrings ;
    private Random                      randomGenerator ;

    /**
     * Initialize all things random
     */
    public RandomLoader ( ) {
        this. randomStrings = new HashMap < String, List < String >> ( ) ;
        this. randomGenerator = new Random ( new Date ( ). getTime ( ) ) ;
    }

    /**
     * Adds or ammends a collection of values to draw from
     */
    public void addRandomStringSource ( String sourceName, List < String > sourceMembers ) {
        if ( ! this. randomStrings. containsKey (sourceName ) ) {
            this. randomStrings. put (sourceName, sourceMembers ) ;
        } else {
            // We have a list of this name, so we add the values
            List < String > existingList = this. randomStrings. get (sourceName ) ;
            for ( String newMember : sourceMembers ) {
                existingList. add (newMember ) ;
            }
        }
    }

    /**
     * Get rid of a list we don't need anymore
     *
     * @param sourceName
     */
    public void dropRandomStringSource ( String sourceName ) {
        if ( this. randomStrings. containsKey (sourceName ) ) {
            this. randomStrings. remove (sourceName ) ;
        }
    }

    /**
     * Gets a random value from a predefined list
     */
    public String getRandomString ( String sourceName ) {
        if ( this. randomStrings. containsValue (sourceName ) ) {
            List < String > sourceCollection = this. randomStrings. get (sourceName ) ;
            int whichValue = this. randomGenerator. nextInt (sourceCollection. size ( ) ) ;
            return sourceCollection. get (whichValue ) ;
        }
        // If we don't have that list we return the requested list name
        return sourceName ;
    }

    /**
     * Get a random String, but not the value specified Good for populating
     *travel to (exclude the from) or from/to message pairs etc
     *
     *@param sourceName
     *            from which list
     *@param excludedResult
     *            what not to return
     *@return
     */
    public String getRandomStringButNot ( String sourceName, String excludedResult ) {
        String result = null ;
        for ( int i = 0 ; i < MAX_RANDOM_TRIES ; i++ ) {
            result = this. getRandomString (sourceName ) ;
            if ( !result. equals (excludedResult ) ) {
                break ;
            }
        }
        return result ;
    }

    /**
     * For populating whole paragraphs of random text LoremIpsum Style
     */
    public String getRandomParagraph ( int numberOfWords ) {
        LoremIpsum li = new LoremIpsum ( ) ;
        return li. getWords (numberOfWords ) ;
    }

    /**
     *Get a date in the future
     */
    public Date getFutureDate ( Date startDate, int maxDaysDistance ) {
        int actualDayDistance = this. randomGenerator. nextInt (maxDaysDistance + 1 ) ;
        DateTime jdt = new org. joda. time. DateTime (startDate ) ;
        DateTime jodaResult = jdt. plusDays (actualDayDistance ) ;
        return jodaResult. toDate ( ) ;
    }

    /**
     * Get a date in the past, good for approval simulation
     */
    public Date getPastDate ( Date startDate, int maxDaysDistance ) {
        int actualDayDistance = this. randomGenerator. nextInt (maxDaysDistance + 1 ) ;
        DateTime jdt = new org. joda. time. DateTime (startDate ) ;
        DateTime jodaResult = jdt. minusDays (actualDayDistance ) ;
        return jodaResult. toDate ( ) ;
    }

    /**
     *Lots of applications are about $$ approvals, so we need a generator
     */
    public float getRandomAmount ( float minimum, float maximum ) {
        // between 0.0 and 1.0F
        float seedValue = this. randomGenerator. nextFloat ( ) ;
        return (minimum + ( (maximum - minimum ) * seedValue ) ) ;
    }

    /**
     * Save the random strings to a JSON file for reuse
     */
    public void saveDatatoJson ( OutputStream out ) {
        Gson gson = new Gson ( ) ;
        PrintWriter writer = new PrintWriter (out ) ;
        gson. toJson ( this, writer ) ;
    }

    /**
     * Load a saved JSON file to populate the random strings
     */
    public static RandomLoader loadDataFromJson ( InputStream in ) {
        InputStreamReader reader = new InputStreamReader (in ) ;
        Gson gson = new Gson ( ) ;
        RandomLoader result = gson. fromJson (reader, RandomLoader. class ) ;
        return result ;
    }
}