Setting instance Variable, before creating an object

Question

So i got this program which sets subject, and grades it.

now i got this piece of code:

package ectsmonitor;

import java.util.Scanner;
import java.util.stream.IntStream;

/**
 *
 * @author JasperF
 */
public class ECTSMonitor {

    private int aantalvakken;
    private final double voldoende = 5.5;
    private String[] vak = new String[aantalvakken];
    private Scanner input = new Scanner(System.in);
    private int[] ECTS = new int[aantalvakken];
    private double[] Cijfer = new double[aantalvakken];
    private int totaalECTS;

    /**
     * @param args the command line arguments
     */

    /**
     * Asks for amount of Subjects, and sets instance variable for size of
     * Arrays
     */
    public void setSubjects() {
        //System.out.println("Hoeveel vakken heb je?");
        //aantalvakken = input.nextInt();
        System.out.println(vak.length);
        for (int x = 0; x < getAantalvakken(); x++) {
            System.out.println("Voer de naam in van je vak!");
            vak[x] = input.next();
            System.out.println("Voer het aantal punten in voor " + vak[x]);
            ECTS[x] = input.nextInt();
            System.out.println("Vak Toegevoegd!!");
        }

    }

    public void setCijfer() {
        for (int x = 0; x < vak.length; x++) {
            System.out.println("Wat is je Cijfer voor " + vak[x] + "?");
            Cijfer[x] = input.nextDouble();
            System.out.println("Voor het vak " + vak[x] + "heb je als cijfer ingevuld " + Cijfer[x]);
        }

    }

    public void Checkscore() {
        for (int x = 0; x < vak.length; x++) {
            if (Cijfer[x] >= voldoende) {
                System.out.println("vak:" + vak[x] + "\t\t\t\t Cijfer: " + Cijfer[x] + "ECTS behaald: " + ECTS[x]);
            } else {
                System.out.println("vak:" + vak[x] + "\t\t\t\t Cijfer: " + Cijfer[x] + "ECTS behaald: 0");
            }

        }

    }

    public void BAS() {
        totaalECTS = IntStream.of(ECTS).sum();

        if (totaalECTS < (totaalECTS * (5 / 6))) {
            System.out.println("PAS OP!!: Je ligt op schema voor een BAS!");
        } else {
            System.out.println("Gefeliciteerd!!: Je bent op weg naar je Propodeuse!!");
        }
    }

    /**
     * @return the aantalvakken
     */
    public int getAantalvakken() {
        return aantalvakken;
    }

    /**
     * @param aantalvakken the aantalvakken to set
     */
    public void setAantalvakken(int aantalvakken) {
        this.aantalvakken = aantalvakken;
    }
}

and i got this piece of code to run it:

public class Run {

    /**
     *
     * @author JasperF
     * @param args
     */
    public static void main(String[] args) {


        ECTSMonitor mon = new ECTSMonitor();


        mon.setSubjects();
        mon.setCijfer();
        mon.Checkscore();
        mon.BAS();

    }
}

now in the first code, the lenght of the arrays is set by the variable 'aantalvakken', but when i run my program, and print the lenght of te array it says 0.

how can i set the variable aantalvakken to set the array length

Uğur Güneri · Accepted Answer · 2014-12-05 12:58:56Z

1

Pass aantalvakken value to constructor. And create ArrayList's depends on aantalvakken at constructor.

public class ECSTMonitor {        
    private int aantalvakken;
    private final double voldoende = 5.5;
    private String[] vak;
    private Scanner input = new Scanner(System.in);
    private int[] ECTS;
    private double[] Cijfer;
    private int totaalECTS;

    public ECSTMonitor(int aantalvakken) {
        this.aantalvakken = aantalvakken;
        vak = new String[aantalvakken];
        ECTS = new int[aantalvakken];
        Cijfer = new double[aantalvakken];
    }

edited Dec 5, 2014 at 12:58

answered Dec 5, 2014 at 12:49

Uğur Güneri

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Comments

Smutje · Accepted Answer · 2014-12-05 12:44:10Z

0

private int aantalvakken;

is not initialized and therefore 0 by default.

answered Dec 5, 2014 at 12:44

Smutje

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Comments

mady · Accepted Answer · 2014-12-05 12:50:42Z

0

try using static variables like below, initialize the variable(aantalvakken) how much array length you want.

public static final int aantalvakken;

or

public static final int aantalvakken=10;

answered Dec 5, 2014 at 12:50

mady

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1 Comment

Uğur Güneri Over a year ago

Please don't advice hard coding.

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