CODEWITHSUNDEEP
javadatecompare
flipd.d.mon
flipd.d.mon

Reputation: 51

Date Object Comparison - Java

I'm having an issue with a program that requires me to compare references to Date objects. The scenario is a Vehicle Showroom, with Vehicles stored in an arraylist.

I have a Vehicle Class

    import java.text.DecimalFormat;
    import java.util.*;
    import java.util.Date;

    public class Vehicle {

private String manufacturer;
private String model;
//private String customerNameSold = null;
private String vehicleID_VIN;
private String dateManufacture;
private String dateSold;

private boolean beenSold;

private char taxBand_A_M;

private double vehicleCost;
private String emissions;



private Customer customerNameSold;
private Date dom;
//private String manuDate;
private Date saleDate;

     //Constructor 7
     public Vehicle (String manu, String mod, String vin, String dateManu, char tax, double cost){

    manufacturer = manu;
    model = mod;
    vehicleID_VIN = vin;
    dateManufacture = dateManu;
    //Add String to Date
    dom = new Date(dateManu);
    taxBand_A_M = tax;
    vehicleCost = cost;
    dateSold = null;
    customerNameSold = null;

    beenSold = false;
}




public String toString() {

    DecimalFormat df = new DecimalFormat("#.00");

    //method calls - do they need this. then method call?
    String s = "\nManufacturer: " + getManu()
            + " \nModel: " + getModel()
            + " \nVIN: " + getVin()
            + " \nDate of Manufacture: " + getManuDate()
            + " \nDate of Manufacture (String to Date): " + getManuDate2()
            + " \nAge of Vehicle: " + getAgeOfVehicle() + " (in WEEKS)"
            + " \nTax Band: " + getTax()
            + " \nEmissions: " + cO2()
            + " \nCost: £" + df.format(getCost())
            + " \nHas Vehicle Been Sold: " + getBeenSold()
            + " \nCustomer: " + getCust()
            + " \nDate Sold: " + getDateSold()
            + " \nDate Sold (String to Date): " + getDateSold2();


    return s;

}

public String getManu() {

    return manufacturer;
}

public String getModel() {

    return model;
}

    ////    public String getCust() {
    ////    
    ////        return customerNameSold;
    ////    }

public Customer getCust() {

    return customerNameSold;
}

public String getVin() {

    return vehicleID_VIN;
}

    public String getManuDate(){

    return dateManufacture;
}

public Date getManuDate2() {

    return dom;
}

public String getDateSold(){

return dateSold;

}

public Date getDateSold2() {

    return saleDate;
}


//CONVENTION SUGGESTS SHOULD BE 'isSold()'
public boolean getBeenSold() {

    return beenSold;
}

public char getTax() {


    return taxBand_A_M;
}

public double getCost() {

    //how to format to 2 decimal places?
    return vehicleCost;
}




public void buyVehicle(String sale, Customer cust) {




    customerNameSold = cust;

    //Add String to Date
    saleDate = new Date(sale);
   dateSold = sale;
    beenSold = true;
}

public String cO2() {


    switch (taxBand_A_M) {
        case 'A':
            emissions = "0-100";
            break;
        case 'B':
            emissions = "101-110";
            break;
        case 'C':
            emissions = "111-120";
            break;
        case 'D':
            emissions = "121-130";
            break;
        case 'E':
            emissions = "131-140";
            break;
        case 'F':
            emissions = "141-150";
            break;
        case 'G':
            emissions = "151-160";
            break;
        default:
            emissions = null;
            break;
    }

    return emissions;
}


public int getAgeOfVehicle() {

    Date now = new Date();
    long diff = now.getTime() - dom.getTime();

    long age = (diff / (1000L * 60 * 60 * 24 * 7));
    return (int) age;
}

}

A Showroom Class

    import java.util.*;

    public class Showroom {

private String showroomName;
private ArrayList<Vehicle> theVehicles;
private Vehicle currVeh = null;
private ArrayList<Vehicle> recentlySold;
private Date dateSold;

private long diff;
private long age;


      //Constructor Method - Takes the name of the Showroom Object & Creates the array list of vehicles
      public Showroom(String name) {
      showroomName = name;
      theVehicles = new ArrayList<Vehicle>();
      }

public String getName() {
    return showroomName;
}

public void setName(String name) {
    //this.showroomName if passed in parameter was named showroomName also
    showroomName = name;
}

    public boolean addVehicle(Vehicle newVehicle) {


    theVehicles.add(newVehicle);
    currVeh = newVehicle;
    return true;


}

public boolean addVehicleAfterCurrent(Vehicle newVehicle) {


    theVehicles.add(theVehicles.indexOf(currVeh) + 1, newVehicle);
    currVeh = newVehicle;
    return true;


}


public Vehicle findVehicle(String vehicleVIN) {
    for (Vehicle v : theVehicles) {
        if (v.getVin().equalsIgnoreCase(vehicleVIN)) {
            System.out.println("Vehicle Found:\n"
                    + v.getManu() + "\n"
                    + v.getModel() + "\n"
                    + v.getVin() + "\n"
                    + theVehicles.indexOf(v) + "\n");
            return v;

            //OR CALL THE toString() METHOD - v.toString()
        }
    }

    System.out.println("Sorry - The Vehicle was not found in the Showroom!\n"
            + theVehicles.indexOf(vehicleVIN) + "\n");

    return null;
}

public Vehicle setCurrentVehicle(Vehicle cv) {

    currVeh = cv;
    return currVeh;
}

public Vehicle getCurrentVehicle() {
    System.out.println("\nCurrentVehicle: " + currVeh);
    return currVeh;
}

public Vehicle nextVehicle() {


    int index = theVehicles.indexOf(currVeh);
    if (index < 0 || index + 1 == theVehicles.size()) {
        System.out.println("\nEnd of the list");
        return null;
    }
    Vehicle v = theVehicles.get(index + 1);
    setCurrentVehicle(v);
    System.out.println("\nThe Former Next Vehicle & Now Current Vehicle: " + v);


    return currVeh;
}

public Vehicle previousVehicle() {

    int index = theVehicles.indexOf(currVeh);
    if (index <= 0) {
        System.out.println("\nNegative Index -1 Before Start of List");
        return null;
    }
    Vehicle v = theVehicles.get(index - 1);
    setCurrentVehicle(v);
    System.out.println("\nThe Former Previous Vehicle & Now Current Vehicle: " + v);


    return currVeh;

}

public void outputArray() {
    for (Vehicle nextVehicle : theVehicles) {
        System.out.println(nextVehicle.getModel() + "\n" + theVehicles.indexOf(nextVehicle));
    }
}


public void outputShowroomDetails() {
    System.out.println("\nSHOWROOM NAME: " + showroomName);
    //output each vehicle in turn
    System.out.println("THE VEHICLES IN THE SHOWROOM:");
    if (theVehicles.isEmpty()) {
        System.out.println("\n*** There are no Vehicles in the Showroom! ***");
    } else {
        for (Vehicle nextVehicle : theVehicles) {
            System.out.println(nextVehicle.toString() + "\n" + theVehicles.indexOf(nextVehicle));
        }
    }

}

public Vehicle setCurrentVehicleByVIN(String vin) {


    System.out.println("\n*** ATTEMPTING TO SET CURRENT VEHICLE BY VIN:\n"
            + vin);
    Vehicle v = findVehicle(vin);
    if (v != null) {
        System.out.println("\nTHE CURRENT VEHICLE: " + "\nARRAY LIST INDEX: " + theVehicles.indexOf(v)
                + v.toString());
    }
    currVeh = v;
    return currVeh;
}


public boolean deleteVehicle(String vin) {
    System.out.println("\nATTEMPTING TO DELETE VEHICLE:\n"
            + "VEHICLE VIN to DELETE: " + vin);
    Vehicle v = findVehicle(vin);
    if (v != null) {
        theVehicles.remove(v);
        System.out.println("VEHICLE *** " + vin + " *** REMOVED!");
        return true;
    }
    return false;
}

//Method not working - null pointer 'long diff' line
public ArrayList<Vehicle> getVehiclesSoldRecently() {

    recentlySold = new ArrayList<Vehicle>();


    //Each vehicle has a sale date
    //Determine the difference between sale date & todays date
    //If the difference is greater than 14 days (2 weeks)  it won't be added to the array
    //If the difference is less than or equal to 14 days (2 weeks), then they will be added to the array



    if (theVehicles.isEmpty()) {
        System.out.println("\n*** The Showroom is Empty!***");
    } else 
    {
        for (Vehicle v : theVehicles) {

            Date now = new Date();




            dateSold = v.getDateSold2();


            long diff = now.getTime() - v.getDateSold2().getTime();
            long age = (diff / (1000L * 60 * 60 * 24 * 7));


            if (age <= 2) {

                recentlySold.add(v);
                System.out.println("\nVEHICLES RECENTLY SOLD: " + v.toString());
            }

        }
    return recentlySold;

    }


}

& a Customer Class

    public class Customer {

private String custName = null;
private String custPhone = null;
private String custEmail = null;

public Customer() {
}

public Customer(String name) {

    custName = name;
    custPhone = "n/a";
    custEmail = "n/a";

}

public Customer(String name, String phone) {

    custName = name;
    custPhone = phone;
    custEmail = "n/a";

}

//***CAN'T HAVE A CONSTRUCTOR DETAILING NAME & EMAIL ONLY
//AS A (String, String) CONSTRUCTOR ALREADY DEFINED
public Customer(String name, String phone, String email) {

    custName = name;
    custPhone = phone;
    custEmail = email;

}

//***AUTO GENERATED GETTERS & SETTERS - this.*
public String getCustName() {
    return custName;
}

public void setCustName(String custName) {
    this.custName = custName;
}

public String getCustPhone() {
    return custPhone;
}

public void setCustPhone(String custPhone) {
    this.custPhone = custPhone;
}

public String getCustEmail() {
    return custEmail;
}

public void setCustEmail(String custEmail) {
    this.custEmail = custEmail;
}

//***AUTO GENERATED TOSTRING METHOD (THOUGH EDITED FOR FORMAT)
@Override
public String toString() {
    String cust = "\n*** CUSTOMER ***"
            + "\nName: " + getCustName()
            + "\nPhone: " + getCustPhone()
            + "\nEmail: " + getCustEmail();

    //System.out.println(cust);

    return cust;
}

}

The ShowroomDriver is

    public class ShowroomDriver {

public static void main(String args[]) {

    Showroom showDrive = new Showroom("ShowroomDriver Showroom");

    System.out.println("\n*** OUTPUT SHOWROOM DETAILS ***");

    showDrive.outputShowroomDetails();

    System.out.println("\n*** CREATE / ADD 4 VEHICLES ***");

    Vehicle sdv1 = new Vehicle("Audi", "R8 Spider", "FAVE 101", "MAR-04-2011", 'E', 45000);
    //Vehicle sdv1 = new Vehicle("Audi", "R8 Spider", "FAVE 101", 03 / 04 / 2011, 'E', 45000);
    System.out.println("\nTesting toString: " + sdv1.toString());

    Vehicle sdv2 = new Vehicle("Tesla", "Model S", "ELEC TRIC", "JAN-01-2013", 'A', 55000);
    //Vehicle sdv2 = new Vehicle("Tesla", "Model S", "ELEC TRIC", 01 / 01 / 2013, 'A', 55000);
    System.out.println("\nTesting to String: " + sdv2.toString());

    Vehicle sdv3 = new Vehicle("Ford", "Cortina", "1212 NUM", "JUN-06-2006", 'D', 55000);
    //Vehicle sdv3 = new Vehicle("Ford", "Cortina", "1212 NUM", 06 / 06 / 2006, 'D', 55000);
    System.out.println("\nTesting to String: " + sdv3.toString());

    Vehicle sdv4 = new Vehicle("VW", "Golf MK 1", "DUB DUB", "NOV-11-1971", 'E', 25000);
    //Vehicle sdv4 = new Vehicle("VW", "Golf MK 1", "DUB DUB", 11/11/1971, 'E', 25000);
    System.out.println("\nTesting to String: " + sdv4.toString());

    showDrive.addVehicle(sdv1);
    showDrive.addVehicle(sdv2);
    showDrive.addVehicle(sdv3);
    showDrive.addVehicle(sdv4);


    System.out.println("\n*** OUTPUT SHOWROOM DETAILS ***");

    showDrive.outputShowroomDetails();

    System.out.println("\n*** BUY 2 VEHICLES ***");

    Customer cust1 = new Customer("Andrew Antivan", "01785 111 111");
    Customer cust2 = new Customer("Belinda Belle", "01782 222 222", "[email protected]");

    sdv1.buyVehicle("JUL-07-2013", cust1);
    sdv2.buyVehicle("MAR-01-2013", cust2);

    showDrive.outputShowroomDetails();

    System.out.println("\n***CREATE 4 VEHICLES ***");

    Vehicle purV1 = new Vehicle("Ford", "Fiesta", "NAT NAT", "MAR-09-2006", 'E', 5000);
    Vehicle purV2 = new Vehicle("Vauxhall", "Corsa", "LEE 123", "JUL-07-2011", 'D', 5500);
    Vehicle purV3 = new Vehicle("Toyota", "Aygo", "JOHN 32A", "FEB-02-2010", 'E', 2000);
    Vehicle purV4 = new Vehicle("Marvel", "Bat Mobile", "KA BOOM", "MAR-11-2008", 'C', 3000);

    System.out.println("\n*** SELL 2 of 4 VEHICLES ***");




    System.out.println("\n*** ADD THE 4 NEW VEHICLES TO SHOWROOM ***");

    showDrive.addVehicle(purV1);
    showDrive.addVehicle(purV2);
    showDrive.addVehicle(purV3);
    showDrive.addVehicle(purV4);



     purV1.buyVehicle("DEC-12-2012", cust1);
    purV2.buyVehicle("DEC-12-2012", cust1);
    purV3.buyVehicle("OCT-18-2013", cust2);
    purV4.buyVehicle("OCT-19-2013", cust2);

            showDrive.outputShowroomDetails();

            showDrive.getVehiclesSoldRecently();




}

}

The program is modified incrementally. Originally the Dates for Manufacture & Sale were passed in (Hardcoded) as String Objects, but now they have to be added as Date Objects.

The problem I am having has occurred only when I try to call the getVehiclesSoldRecently() method. I receive a null pointer exception warning, that suggests the issue is occurring due to the 'diff...' line in that Method.

Errors received:

Exception in thread "main" java.lang.NullPointerException

at Showroom.getVehiclesSoldRecently(Showroom.java:197)

    diff=now.getTime()-v.getDateSold2().getTime();

at ShowroomDriver.main(ShowroomDriver.java:93)

    showDrive.getVehiclesSoldRecently();

Any help to indicate where I'm going wrong would be appreciated.

Thanks.

* EDIT *

The method signatures for all methods except those that getDates have to remain the same, meaning that String parameters had to be passed in & then converted to Date objects.

Upvotes: 0

Views: 469

Answers (1)

BobTheBuilder
BobTheBuilder

Reputation: 19284

It means that:

v.getDateSold2()

returns null in:

diff=now.getTime()-v.getDateSold2().getTime();

So what you actually do is calling getTime() on null Object. You need to check if v.getDateSold2() is null before trying to access it.

If it is null, you can ignore it or print something else.

Upvotes: 1

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