Thread: Sorting a Multi-Dimensional String array

Good evening everyone,

I am currently just a student of Java and am stuck on one part of my assignment. I have a multi-dimension array created from a CSV file. I can get it to print no problem however I need to sort it first according to a specific column.
The array looks like this;

Date------------Open----High----Low-----Close---AdjClose---Volume
2000-09-01___33.05__33.45__32.75__33.38__33.38____45869
2000-09-05___33.95__33.99__33.42__33.80__33.80____55722

there is a lot more but did not want to type them all,

I need to sort this array according to the 'Close' column going from highest to lowest.

I did try a bubble sort (rookie move I know), but all it did was change the values in the Close column from high to low, the rest of the rows remained in place.

Can anyone send a suggestion or send a sample to help me past this problem. Keep in mind that ALL fields are Strings.

I also tried the following:

I created two methods that separate the original array and created two more arrays, one is a Date[] and stores just the first column in a date format and the second array is a float[][] which stores the remaining values as floats.
The float[][] array I can sort using the following,

    public void sortDataArray(float[][] arr, int colNum) {
 
        Arrays.sort(arr, new Comparator<float[]>() {
 
            @Override
            public int compare(float[] val1, float[] val2) {
 
                if (val1[columnSort] < val2[columnSort]) {
                    return 1;
                } else {
                    return -1;
                }
            }
        });
    }

I can print this one and all the float values arrange properly, but I do not know how to include the dates in the printout.

I am really hoping someone out there can help me, my assignment is due soon, and this is the second last thing I need to get done.
(last thig is to implement a lambda expression somewhere in my code but I will deal with that after I get this fixed)

Thanks.

Hello Norm,
Here is the my entire project so far. I wasn't sure I understood what particular code you wanted to see, so I figure post it all.
Some comments are in the code just as a reminder to me to do some repairs, you can ignore those.

 
package AssignmentThree;
 
import java.io.*;
import java.util.Scanner;
import java.util.StringTokenizer;
import java.util.logging.Level;
import java.util.logging.Logger;
import static java.nio.file.AccessMode.*;
import java.nio.file.Path;
import java.nio.file.Paths;
 
/**
 * Java Intermediate - Assignment 3
 * Working with CSV file located in C:\temp
 * @author Ken Leduc
 * @date July 26, 2021
 */
public class ReadFiles {
    String fullPath = "C:/temp/NewCrudeOil.csv";
    File file = new File(fullPath);
    Path filePath = Paths.get(fullPath);
    Scanner scan;
    int printArea = 0;
    int rowCount;
    int columnCount = 0;
    String line = "";
    int countColumn;
    int countLine = 0;
    String[][] fileArray;    
 
    /**
     * FileCheck, looks in the file location to make sure 
     * file does exist.
     */
    public void FileCheck(){       
 
       try
        {
            filePath.getFileSystem().provider().checkAccess(filePath, READ, EXECUTE);                   
        }  
 
        catch(Exception FileNotFoundException)
        {
            System.out.println("File does not exist!");
            System.exit(-1);
        } 
    }   
 
    /**
     * RowCount, counts the total rows in the CSV file
     * Assigns that value to rowCount variable.
     */
    public int getRowCount(){
 
        try {
            BufferedReader br = new BufferedReader(new FileReader(file));
 
            while((line = br.readLine()) != null){
                rowCount++;
            }         
 
 
        } 
        catch (FileNotFoundException ex) {
            System.out.println("Row count error.");           
            Logger.getLogger(ReadFiles.class.getName()).log(Level.SEVERE, null, ex);
        }
        catch (IOException ex) {
            System.out.println("There was an error counting the rows.");
            Logger.getLogger(ReadFiles.class.getName()).log(Level.SEVERE, null, ex);
        } 
 
        return rowCount;
    }
 
    /**
     * CSVConvert, takes the CSV file and stores all the data in a 2D array
     * Takes each token and stores them in the appropriate location in the array.
     */
    public String[][] getCSVConvert(){
        fileArray = new String[rowCount][7];       
 
        try{
            BufferedReader br = new BufferedReader(new FileReader(file));
 
            while((line = br.readLine()) != null){
 
                StringTokenizer separator = new StringTokenizer(line, ",");
 
                    for(countColumn = 0; countColumn < 7; countColumn++){ 
                        fileArray[countLine][countColumn] = separator.nextToken(); 
                    }
                ++countLine;
            } 
 
       }      
        catch(IOException e){
            System.out.println("CSVConvert errored, check code");
        }
 
        return fileArray;
   }
 
    /**
     * PrintArray, takes the fileArray and neatly prints out the results 
     * to the screen.
     */
    public void PrintArray(){
        System.out.println("\nCrude Oil Stock Prices.\nStarting September 2000 to December 2013.");
            printHeader();
 
        try
        {
            if(printArea == 0){
                for(int lineCount = 0; lineCount < countLine; lineCount++){ 
                    for(int columnCount = 0; columnCount < countColumn; columnCount++){
                        System.out.printf("%-15s", fileArray[lineCount][columnCount]); 
                    }
                System.out.println(); 
                printArea = rowCount;
                }
            }
            else{
                for(int lineCount = 0; lineCount < printArea; lineCount++){ 
                    for(int columnCount = 0; columnCount < countColumn; columnCount++){
                        System.out.printf("%-15s", fileArray[lineCount][columnCount]); 
                    }
                System.out.println();    
                }            
            }
            System.out.println("First " + printArea + " lines were printed.");
        }
        catch(Exception e)
            {
            System.out.println("Printing error!");
            }
    }
 
    /**
     * Copies the array created in CSVConvert to  new array called newArray
     * @return newArray
     */
    public String[][] getArray(){
        String[][] newArray = fileArray;
 
        return newArray;
    }
 
    /**
     * User enters the number of rows to print.
     * @return printArea
     */
    public int getPrintArea() {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter the number of rows to print or enter 0 for all rows. -> ");
 
    try{  
        int number = input.nextInt();
        if(number > countLine){
                System.out.println("You selected a number that exceeds the total number of rows\n"
                                    + "Please try a new number.\n");
                getPrintArea();                
        }
        else if(number<0){
                System.out.println("Please enter a whole number.\n");
                getPrintArea();
        }
 
        else      
        {        
                printArea = number;
        }   
    }
    catch(Exception e){
        System.out.println("You entered an incorrect number, please try again.\n");
        getPrintArea();        
    }    
        System.out.println();
        return printArea;
    }
 
    /**
     * Prints and formats the header for all the displayed data
     */
    public void printHeader(){
        System.out.printf("%-14s %-14s %-14s %-14s %-14s %-14s %-14s", "Date", "Open", "High", "Low", "Close", "Adj Close", "Volume");
        System.out.println(); 
    }
}

This is the class that I need to insert the sorting method into,

package AssignmentThree;
 
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
 
public class Calculations extends ReadFiles {
 
    ReadFiles readFiles = new ReadFiles();
    int countingRows = readFiles.getRowCount();
    int innerCount = 0;
    int outerCount = 0;
    int columnSort = 4; // column in the array to base the sort on
    String dataLine = "";
    String[][] newArray = readFiles.getCSVConvert();
    String[] dateArray = new String[countingRows];
    float[][] dataArrayValues;
    float[][] dataArrayAll;
    float highOpening;
    float highClosing;
    float lowOpening;
    float lowClosing;
    Date[] dayArray;
    Date highOpeningDate;
    Date highClosingDate;
    Date lowOpeningDate;
    Date lowClosingDate;
 
    /**
     * Calculations constructor
     */
    public void Calculations() {
        getCreateDateArray();
        getCreateDataArray();
    }
 
    /**
     * Creates a 2D array of the data only, no dates
     */
    public float[][] getCreateDataArray() {
 
        int countLine1 = 0;
        dataArrayValues = new float[countingRows][6];
        dataArrayAll = new float[countingRows][7];
 
        // creates an array of only the data
        try {
            BufferedReader reader = new BufferedReader(new FileReader(file));
 
            while ((dataLine = reader.readLine()) != null) {
 
                for (int countColumn1 = 0; countColumn1 < 6; countColumn1++) {
                    dataArrayValues[countLine1][countColumn1] = Float.valueOf(newArray[countLine1][countColumn1 + 1]);
                }
                ++countLine1;
            }
 
        } catch (IOException e) {
            System.out.println("CSVConvert errored, check code");
        }
 
        return dataArrayValues;
    }
 
    /**
     * Prints the data Array list
     *
     * @param input
     */
    public void printDataArray(float[][] input) {
 
        System.out.println("\nThe list of data within the CSV file.\n");
        System.out.printf("%-14s %-14s %-14s %-14s %-14s %-14s", "Open", "High", "Low", "Close", "Adj Close", "Volume");
        System.out.println("");
 
        for (int lineCount2 = 0; lineCount2 < countingRows; lineCount2++) {
            for (int columnCount2 = 0; columnCount2 < 6; columnCount2++) {
                System.out.printf("%-15s", dataArrayValues[lineCount2][columnCount2]);
            }
            System.out.println();
        }
    }
 
    /**
     * Creates an 1D array of all the dates
     */
    public Date[] getCreateDateArray() {
 
        SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yy");
        dayArray = new Date[countingRows];
 
        try {
            BufferedReader reader = new BufferedReader(new FileReader(file));
 
            while ((line = reader.readLine()) != null) {
 
                try {
                    dayArray[innerCount] = sdf.parse(newArray[innerCount][0]);
                    innerCount++;
                } catch (Exception e) {
                }
 
            }
        } catch (IOException e) {
            System.out.println("CSVConvert errored, check code");
            System.exit(-1);
        }
 
        //printDateArray(dayArray);
        return dayArray;
    }
 
    /**
     * Prints the 1D DateArray list
     *
     * @param input
     */
    public void printDateArray(Date[] input) {
        System.out.println("\nThe list of dates within the CSV file.\n");
        for (int innerCount = 0; innerCount < countingRows; innerCount++) {
            System.out.println(input[innerCount]);
        }
 
    }
 
    /**
     * Calculates some basic values
     */
    public void basicCalcs() {
        highOpening = dataArrayValues[0][0];
        highClosing = dataArrayValues[0][3];
        lowOpening = dataArrayValues[0][0];
        lowClosing = dataArrayValues[0][3];
 
        for (int highLowSearch = 0; highLowSearch < countingRows; highLowSearch++) {
            //highest and lowest value in the Open column
            if (dataArrayValues[highLowSearch][0] > highOpening) {
                highOpening = dataArrayValues[highLowSearch][0];
                highOpeningDate = dayArray[highLowSearch];
            }
            if (dataArrayValues[highLowSearch][0] < lowOpening) {
                lowOpening = dataArrayValues[highLowSearch][0];
                lowOpeningDate = dayArray[highLowSearch];
            }
 
            //highest and lowest value in the Close column
            if (dataArrayValues[highLowSearch][3] > highClosing) {
                highClosing = dataArrayValues[highLowSearch][3];
                highClosingDate = dayArray[highLowSearch];
            }
            if (dataArrayValues[highLowSearch][3] < lowClosing) {
                lowClosing = dataArrayValues[highLowSearch][3];
                lowClosingDate = dayArray[highLowSearch];
            }
        }
 
        //the dates are print 'null', may have something to to with the date format above
        System.out.println("\nHigh/Low Stats\n");
        System.out.println("Highest opening value is " + highOpening + ", on " + highOpeningDate);
        System.out.println("Highest closing value is " + highClosing + ", on " + highClosingDate);
        System.out.println("Lowest opening value is " + lowOpening + ", on " + lowOpeningDate);
        System.out.println("Lowest closing value is " + lowClosing + ", on " + lowClosingDate);
    }
 
    /**
     * Sorts the float[][] without the date column
     * @param arr
     * @param colNum 
     */
    public void sortDataArray(float[][] arr, int colNum) {
 
        Arrays.sort(arr, new Comparator<float[]>() {
 
            @Override
            public int compare(float[] val1, float[] val2) {
 
                if (val1[columnSort] < val2[columnSort]) {
                    return 1;
                } else {
                    return -1;
                }
            }
        });
    }  
 
    /**
     * This method only sorts the 'close' column not the entire rows
     */
    public void printSortedArray() {
        System.out.println("\n\tTop 10 based on their closing values.");
        printHeader();
        for (int row = 0; row < 10; row++) {
            System.out.printf("%-15s", newArray[row][0]);
 
            for (int column = 0; column < dataArrayValues[0].length; column++) {
                System.out.printf("%-15s", dataArrayValues[row][column]);
            }
            System.out.println();
        }
    }
 
}

This is the last class that I need to have in my assignment,

package AssignmentThree;
 
import java.util.Scanner;
 
public class DataAnalyzer extends Calculations {       
        ReadFiles readFiles = new ReadFiles();
        Calculations calc = new Calculations();
 
    /**
     * Main method calls each method,
     * with a screen printout of its status.
     * @param args 
     */
    public static void main(String[] args) {        
        DataAnalyzer newFile = new DataAnalyzer();
        newFile.FileVerification();
        newFile.CountRows();
        newFile.FileConvert();
        newFile.Printing();
 
 
    }
 
    /**
     * FileVerification, ensures a file is there and accessible
     */
    public void FileVerification(){
        try{
            readFiles.FileCheck();
            System.out.print("File exists..... ");
        }
        catch(Exception e){
            System.out.println("File does not exist!");
            System.exit(-1);
        }        
    }
 
    /**
     * CountRows, runs the method in the ReadFiles class and prints the total rows
     */
    public void CountRows(){ 
        try{
 
            System.out.println("Total number of rows = " + readFiles.getRowCount());
 
        }
        catch(Exception e){
 
            System.exit(-1);
        } 
    }
 
    /**
     * FileConvert, runs the CSVConvert method in the ReadFiles class
     * Displays, appropriate message based on the outcome.
     */
    public void FileConvert(){
 
        try{
            readFiles.getCSVConvert();
            System.out.println("CSV successfully converted to an array.");
        }
        catch(Exception e){
            System.out.println("CSVConvert errored, check code");
        }
    }
 
    /**
     * Printing, runs the print methods from the ReadFiles and Calculations classes.
     */
    public void Printing(){
            readFiles.getPrintArea();
            readFiles.PrintArray();
 
 
            Scanner inputValue = new Scanner(System.in);
 
            // printing all the dates
            System.out.print("\nWould you like to print all the dates in the CSV file? y/n -> ");
            String printDates = inputValue.nextLine();
 
            if(printDates.equals("y")){
                getCreateDateArray();
                printDateArray(dayArray);
            }
 
            // printing the data
            System.out.print("\nWould you like to print all the data in the CSV file? y/n -> ");
            String printData = inputValue.nextLine();
 
            if(printData.equals("y")){
                getCreateDataArray();
                printDataArray(dataArrayValues);
            }
 
            // printing the High/Low stats
            System.out.print("\nWould you like to print the high and low stats from the CSV file? y/n -> ");
            String basicData = inputValue.nextLine();
 
            if(basicData.equals("y")){
                getCreateDateArray();
                getCreateDataArray();
                basicCalcs();
            }
 
            // printing the top ten stats
            System.out.print("\nWould you like to print the top ten stats from the CSV file? y/n -> ");
            String topTenData = inputValue.nextLine();
 
            if(topTenData.equals("y")){
 
                sortDataArray(dataArrayValues, columnSort);
                printSortedArray();
            }
 
            calc.Calculations();
    }
}

I really hope you can help me with this,

Hello Norm,
I've been playing with this this all day, first, I removed all the 'extends' as you made a very good point. Second, I tried to use the following code inside of a for loop,

if(newArray[row][3] > newArray[row-1][3])

but it tells me the following error: bad operand types for binary operator >

We haven't touched on the "Comparator" function in java yet, I did watch a dozen youtube videos on this, but got even more confused.


So to get me by, and so I can have a program that I can hand in, I am going to use the following to just sort the float[][] array that I created of just the data.

        Arrays.sort(arr, new Comparator<float[]>() {
 
            @Override
            public int compare(float[] val1, float[] val2) {
 
                if (val1[columnSort] < val2[columnSort]) {
                    return 1;
                } else {
                    return -1;
                }
            }
        });

and the following to print out the top 10,

        System.out.println("\n\tTop 10 based on their closing values.");
        System.out.printf("%-14s %-14s %-14s %-14s %-14s %-14s", "Open", "High", "Low", "Close", "Adj Close", "Volume");
        //printHeader();
        System.out.println();
        for (int row = 0; row < 10; row++) {                      
            for (int column = 0; column < dataArrayValues[0].length; column++) {
                System.out.printf("%-15s", dataArrayValues[row][column]);
            }
            System.out.println();
 
    }

it does display the top ten based on the 'Close' value, it just doesn't show the corresponding date, may lose a mark on this, but it is better than having that feature not working at all.

I do have till Monday night to continue to play with it and possibly figure it out, if I do, I will re-post it here.

Thanks for your time,

Hi Norm,
I did it, it took a while to learn and understand the code but this is what I was able to come up with, (with a little help from Google)

    public void topTenDataArrayWithPrint() {
         Arrays.sort(newArray, new Comparator<String[]>() {
 
            @Override
            public int compare(final String[] first, final String[] second) {
                return Double.valueOf(second[4]).compareTo(
                        Double.valueOf(first[4])
                );
            }
        });
 
        System.out.println("\n\tTop 10 based on their closing values.");
        System.out.printf("%-14s %-14s %-14s %-14s %-14s %-14s %-14s", "Date", "Open", "High", "Low", "Close", "Adj Close", "Volume");
        System.out.println();
 
 
        for (int row = 0; row < 10; row++) {                      
            for (int column = 0; column < newArray[0].length; column++) {
                System.out.printf("%-15s", newArray[row][column]);
            }
            System.out.println();
        }       
    }

I believe this is what you were trying to explain to me before, all I know is that it works.