/**

* Write a program, which reads in n grades (of int between 0 and 100, inclusive)

* from a text file called "grades.in" and displays the histogram horizontally

* and vertically.

*

* The file has the following format:

* numStduents:int

* grade1:int grade2:int .... gradeN:int

*

* For example:

* 15

* 49 50 51 59 0 5 9 10 15 19 50 55 89 99 100

*

* The output shall consist of a horizontal histogram and a vertical histogram

* as follows:

*

* 0 - 9: ***

* 10 - 19: ***

* 20 - 29:

* 30 - 39:

* 40 - 49: *

* 50 - 59: *****

* 60 - 69:

* 70 - 79:

* 80 - 89: *

* 90 -100: **

*

* *

* *

* * * *

* * * * *

* * * * * * *

* 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-100

*/

package javaexercises.methods;

import java.io.*;

import java.util.Scanner;

public class GradesHistogram {

private int[] grades;

private int[] bins = new int[10];

public static void main(String[] args) {

GradesHistogram aGradesHistogram = new GradesHistogram();

aGradesHistogram.readGrades("grades.in");

//aGradesHistogram.printGrades();

aGradesHistogram.computeHistogram();

//aGradesHistogram.printBins();

aGradesHistogram.printHistogramHorizontal();

aGradesHistogram.printHistogramVertical();

}

// check grade value

private boolean isGradeValid(int grade) {

return (0 <= grade && grade <= 100);

}

/**

* Read the grades from "filename", store in "grades" array.

* Assume that the inputs are valid.

*/

private void readGrades(String filename)

{

try {

String filepath = getClass().getResource(filename).getPath();

Scanner file = new Scanner(new File(filepath));

// read number of students' grades

if ( ! file.hasNextInt()) {

System.out.println("Error! Not found students number.");

return;

}

int n = file.nextInt();

// init grades array

grades = new int[n];

// read grades

for(int i = 0; i < n; i++) {

if ( ! file.hasNextInt()) {

continue;

}

grades[i] = file.nextInt();

}

}

catch (FileNotFoundException e) {

System.out.println("Error! File \"grades.in\" not found.");

}

}

/**

* Based on "grades" array, populate the "bins" array.

*/

private void computeHistogram()

{

for(int i = 0; i < grades.length; i++) {

int j = (grades[i] == 100) ? 9 : grades[i] / 10;

bins[j] += 1;

}

}

/**

* Print histogram based on the "bins" array.

*/

private void printHistogramHorizontal()

{

System.out.println();

for(int i = 0; i < bins.length; i++)

{

int delta = (i == bins.length - 1) ? 10 : 9;

System.out.printf("%2d -%3d:", (i*10), (i*10+delta));

for(int j = 0; j < bins[i]; j++) {

System.out.print("*");

}

System.out.println();

}

}

/**

* Print histogram based on the "bins" array.

*/

private void printHistogramVertical()

{

// find out number of rows to output histogram

int maxBin = bins[0];

for(int i = 0; i < bins.length; i++) {

maxBin = (bins[i] > maxBin) ? bins[i] : maxBin;

}

// print histogram

System.out.println();

for(int i = maxBin; i >= 0; i--)

{

if (i == 0)

{

for(int j = 0; j < bins.length; j++)

{

int delta = (j == bins.length - 1) ? 10 : 9;

System.out.printf("%2d-%-2d ", (j*10), (j*10+delta));

}

}

else {

for(int j = 0; j < bins.length; j++)

{

String str = (bins[j] < i ) ? " " : "*";

System.out.printf("%3s%-2s ", str, " ");

}

}

System.out.println();

}

}

/**

* Print students' grades

*/

private void printGrades()

{

for(int i = 0; i < grades.length; i++) {

System.out.print(grades[i]+" ");

}

System.out.println();

}

/**

* Print students' grades

*/

private void printBins()

{

for(int i = 0; i < bins.length; i++) {

System.out.print(bins[i]+" ");

}

System.out.println();

}

}