Histogram.java

import java.util.*;
/**
 * Created by Connor on 11/19/15.
 */
public class Histogram {
    private int [] values;
    private int interval;

    public Histogram(){
        values = new int[100];
        interval = 10;
    }

    public int getInterval(){
        return this.interval;
    }

    public void add(int x){
        values[x-1]++;
    }
    public void changeInterval(int newInterval){
        this.interval = newInterval;
    }

    public int countValues(int start, int end){
        int counter = 0;

        for (int i = start-1; i < end; i++) {
            counter += values[i];
        }

        return counter;
    }

    public void print(){
        for (int i = 1; i <= 100 ; i+=interval) {
            System.out.print(i + " - " + (i + interval-1));

            if (i == 1)
                System.out.print("   |");
            else if (i+interval-1 == 100)
                System.out.print(" |");
            else System.out.print("  |");
            for (int j = 0; j < countValues(i,i + interval-1); j++) {
                System.out.print("*");
            }
            System.out.println();
        }


    }

    public static void main(String [] args)
    {
        Histogram histo = new Histogram();
        Random rand = new Random();


        for(int i = 1; i<=100; i++)
        {
            histo.add(rand.nextInt(100)+1);  //generating 100 random integers between 1 and 100.
            //Adding them to the histogram as well
        }

        histo.print();

        System.out.println("\nChanging the interval size to 20 and re-printing...\n");

        histo.changeInterval(20);
        histo.print();
    }
}