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Return user input into setter function

I have been working on an assignment and i am stuck at here. Basically i have 1 class which defines all functions and members.
And another class to initialize and manipulate objects.
Here is my first class code.
public class cyryxStudent_association {
String studentID, studentName, studentCourse_level, studentTitle;
int course_completed_year;
static double registration_fee;
double activity_fee;
double total_amt;
//Default constructor
cyryxStudent_association ()
{
studentID = "Null";
studentName = "Null";
studentCourse_level = "Null";
studentTitle = "Null";
course_completed_year = 0;
}
//Parameterized Constructor
cyryxStudent_association (String id, String name, String course_level, String title, int ccy)
{
this.studentID = id;
this.studentName = name;
this.studentCourse_level = course_level;
this.studentTitle = title;
this.course_completed_year = ccy;
}
//Getters
public String getStudentID ()
{
return studentID;
}
public String getStudentName ()
{
return studentName;
}
public String getStudentCourse_level ()
{
return studentCourse_level;
}
public String getStudentTitle ()
{
return studentTitle;
}
public int getCourse_completed_year ()
{
return course_completed_year;
}
public double getRegistration_fee ()
{
return registration_fee;
}
public double getActivity_fee ()
{
return findActivity_fee(registration_fee);
}
public double getTotal_amt ()
{
return total_amt(registration_fee, activity_fee);
}
//Setters
public void setStudentID (String id)
{
studentID = id;
}
public void setStudentName (String name)
{
studentName = name;
}
public void setStudentCourse_level (String course_level)
{
studentCourse_level = course_level;
}
public void setStudentTitle (String title)
{
studentTitle = title;
}
public void setCourse_completed_year (int ccy)
{
course_completed_year = ccy;
}
//Find registration fee method
public static double findRegistration_fee (String course_level)
{
if (course_level.equalsIgnoreCase("Certificate"))
{
registration_fee = 75;
}
else if (course_level.equalsIgnoreCase("Diploma"))
{
registration_fee = 100;
}
else if (course_level.equalsIgnoreCase("Degree"))
{
registration_fee = 150;
}
else if (course_level.equalsIgnoreCase("Master"))
{
registration_fee = 200;
}
return registration_fee;
}
//Find activity method
public static double findActivity_fee (double registration_fee)
{
return registration_fee * 0.25;
}
//Find total amount
public static double total_amt (double registration_fee, double activity_fee)
{
return registration_fee + activity_fee;
}
//To string method
public String toString ()
{
return "ID: "+getStudentID()+"\nName: "+getStudentName()+"\nCourse Level:
"+getStudentCourse_level()+"\nTitle: "+getStudentTitle()+"\nCourse Completed Year:
"+getCourse_completed_year()+"\nRegistration Fee: "+getRegistration_fee()+"\nActivity Fee:
"+getActivity_fee()+"\nTotal Amount: "+getTotal_amt ();
}
}
And here is my second class code.
import java.util.Scanner;
public class test_cyryxStudent_association {
public static void main (String[] args)
{
Scanner sc = new Scanner (System.in);
int num, i;
System.out.println("Welcome!");
System.out.println("\nEnter the number of students: ");
num = sc.nextInt();
sc.nextLine();
cyryxStudent_association Std[] = new cyryxStudent_association[num];
for (i = 0; i < Std.length; i++)
{
System.out.println("\nEnter ID: ");
Std[i].setStudentID(sc.nextLine());
System.out.println("Enter Name: ");
Std[i].setStudentName(sc.nextLine());
System.out.println("Enter Course Level [Certificate, Diploma, Degree, Master]: ");
Std[i].setStudentCourse_level(sc.nextLine());
System.out.println("Enter Title: ");
Std[i].setStudentTitle(sc.nextLine());
Std[i].getRegistration_fee();
Std[i].getActivity_fee();
Std[i].getTotal_amt();
}
for (i = 0; i < Std.length; i++)
{
System.out.println("\nStudent " + i + 1 + " Information");
System.out.println("===================================");
Std[i].toString();
}
sc.close();
}
}
I get an error when values in the for loop. Can someone help me? I'm pretty new to programming and studying java for 2 months now. What am i doing wrong?
Here is my objectives.
Create an array of objects and get user input for number of objects to be manipulated.
Read and display array of object values.
Thank you!

You have to initialize the objects of your array.
After the line:
cyryxStudent_association Std[] = new cyryxStudent_association[num];
do a for loop like:
for(i = 0; i<std.length; i++){
std[i] = new cyryxStudent_association();
}

Testing (if..Else if...Else) statement (not working)

Testing an if else statement that does not seem to be working
Assuming it has something to do with possibly changing the IF else to the getter instead of setter?
or something to do with the variable returning an INT instead of string?
little confused been rearranging and modifying this code for a while now and cant get it to work
//package Driver2;
import java.util.Scanner;
class Person{
private String name;
private String address;
private String number;
private int customerPurchase = 0;
//Constructors
public Person(String name, String address, String number, int customerPurchase){
this.name = name;
this.address = address;
this.number = number;
this.customerPurchase = customerPurchase;
}
public Person(){}
//Accessors
public String getName(){
return this.name;
}
public String getAddress(){
return this.address;
}
public String getNumber(){
return this.number;
}
public int getcustomerPurchase(){
return this.customerPurchase;
}
//Mutators
public void setName(String n){
this.name = n;
}
public void setAddress(String a){
this.address = a;
}
public void setNumber(String n){
this.number = n;
}
public void setcustomerPurchase(int a){
this.customerPurchase = a;
}
public void setcustomerDiscount(int r)
{
r = this.customerPurchase;
if (r > 500)
{
System.out.print("5%");
}
else if (r >= 1000)
{
System.out.print("6%");
}
else if (r >= 1500)
{
System.out.print("7%");
}
else if (r >= 2000)
{
System.out.print("10%");
}
else
{
System.out.print("");
}
}
}
///////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////
class Customer extends Person{
private String customerNumber;
private boolean recieveMail;
private int customerDiscount;
//Constructors
public Customer(String name, String address, String number, String customerN, boolean rm, int customerPurchase) {
super(name, address, number, customerPurchase);
this.customerNumber = customerN;
this.recieveMail = rm;
}
public Customer(){}
//Accessors
public String getCustomerNumber(){
return this.customerNumber;
}
public boolean getRecieveMail(){
return this.recieveMail;
}
public int getcustomerDiscount()
{
return customerDiscount;
}
//Mutators
public void setCustomerNumber(String c){
this.customerNumber = c;
}
public void setRecieveMail(boolean r){
this.recieveMail = r;
}
}
///////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////
class Driver1 extends Customer
{
//private int customerPurchase = 0;
//Constructors
/* public Driver1(String name, String address, String number, String customerN, boolean rm, int customerPurchase)
{
super();
this.customerPurchase = customerPurchase;
//this.customerDiscount = customerDiscount;
}*/
public Driver1(String name, String address, String number, String customerN, boolean rm, int customerPurchase) {
//super(name, address, number, customerPurchase, customerN, rm);
//this.customerPurchase = customerN;
//this.customerDiscount = pc;
}
public Driver1()
{}
//Accessors
/*
public int getcustomerDiscount()
{
return this.customerDiscount;
}
/*
#Override
public int getcustomerPurchase()
{
return this.customerPurchase;
}
//Mutators
#Override
public void setcustomerPurchase(int c)
{
this.customerPurchase = c;
}*/
/*
public void setcustomerDiscount(int r)
{
this.customerPurchase = r;
if (r >= 500)
{
System.out.print("5%");
}
else if (r >= 1000)
{
System.out.print("6%");
}
else if (r >= 1500)
{
System.out.print("7%");
}
else if (r >= 2000)
{
System.out.print("10%");
}
else
{
System.out.print("");
}
}
*/
}
///////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////
public class Main
{
public static void main(String args[]){
Scanner scanner = new Scanner(System.in);
System.out.print("Enter name of customer:");
String name1 = scanner.nextLine();
System.out.print("Enter address of customer:");
String address1 = scanner.nextLine();
System.out.print("Enter phone number of customer:");
String number1 = scanner.nextLine();
System.out.print("Enter customer number:");
String customerNumber = scanner.nextLine();
System.out.print("Enter yes/no -- does the customer want to recieve mail?:");
String answer = scanner.nextLine();
boolean recieveMail = (answer.equals("yes"));
System.out.print("Enter amount customer has spent:");
int customerPurchase = scanner.nextInt();
Customer customer = new Customer(name1, address1, number1, customerNumber, recieveMail, customerPurchase);
System.out.println("\nCustomer: ");
System.out.println("Name: "+customer.getName());
System.out.println("Address: "+customer.getAddress());
System.out.println("Phone Number: "+customer.getNumber());
System.out.println("Customer Number: "+customer.getCustomerNumber());
System.out.println("Recieve Mail?: "+customer.getRecieveMail());
System.out.println("Amount Purchased: "+customer.getcustomerPurchase());
System.out.println("Percent off: "+customer.getcustomerDiscount());
}
}

The code you have pasted require some changes actually.Assuming you need to return the discount percentage based on the customer input you need to do the following changes.
1) You have a setCustomerDiscount in Person class but the entity you are dealing here is of Customer type so you need to add the setCustomerDiscount in the Customer class instead of Person class.
2) As you want to show the percentage in String(as per your sysout statements/ you can also change to Int as required) you need to change the return type to String instead of Int.
3) Another thing is your order of the if/else if conditions should be in descending order.
Once you fix them, you can get your output as expected.
Below I have made those changes:
import java.util.Scanner;
class Person{
private String name;
private String address;
private String number;
private int customerPurchase = 0;
//Constructors
public Person(String name, String address, String number, int customerPurchase){
this.name = name;
this.address = address;
this.number = number;
this.customerPurchase = customerPurchase;
}
public Person(){}
//Accessors
public String getName(){
return this.name;
}
public String getAddress(){
return this.address;
}
public String getNumber(){
return this.number;
}
public int getcustomerPurchase(){
return this.customerPurchase;
}
//Mutators
public void setName(String n){
this.name = n;
}
public void setAddress(String a){
this.address = a;
}
public void setNumber(String n){
this.number = n;
}
public void setcustomerPurchase(int a){
this.customerPurchase = a;
}
public void setcustomerDiscount(int r)
{
}
}
///////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////
class Customer extends Person{
private String customerNumber;
private boolean recieveMail;
private String customerDiscount;
//Constructors
public Customer(String name, String address, String number, String customerN, boolean rm, int customerPurchase) {
super(name, address, number, customerPurchase);
this.customerNumber = customerN;
this.recieveMail = rm;
}
public Customer(){}
//Accessors
public String getCustomerNumber(){
return this.customerNumber;
}
public boolean getRecieveMail(){
return this.recieveMail;
}
public String getcustomerDiscount()
{
return customerDiscount;
}
//Mutators
public void setCustomerNumber(String c){
this.customerNumber = c;
}
public void setRecieveMail(boolean r){
this.recieveMail = r;
}
public void setcustomerDiscount(int r)
{
String customerDiscount = "";
if (r >= 2000)
{
customerDiscount="10%";
System.out.print("10%");
}
else if (r >= 1500)
{
customerDiscount="7%";
System.out.print("7%");
}
else if (r >= 1000)
{
customerDiscount="6%";
System.out.print("6%");
}
else if (r > 500)
{
customerDiscount="5%";
System.out.print("5%");
}
else
{
System.out.print("");
}
this.customerDiscount = customerDiscount;
}
}
public class TestMain
{
public static void main(String args[]){
Scanner scanner = new Scanner(System.in);
System.out.print("Enter name of customer:");
String name1 = scanner.nextLine();
System.out.print("Enter address of customer:");
String address1 = scanner.nextLine();
System.out.print("Enter phone number of customer:");
String number1 = scanner.nextLine();
System.out.print("Enter customer number:");
String customerNumber = scanner.nextLine();
System.out.print("Enter yes/no -- does the customer want to recieve mail?:");
String answer = scanner.nextLine();
boolean recieveMail = (answer.equals("yes"));
System.out.print("Enter amount customer has spent:");
int customerPurchase = scanner.nextInt();
scanner.close();
Customer customer = new Customer(name1, address1, number1, customerNumber, recieveMail, customerPurchase);
System.out.println("\nCustomer: ");
System.out.println("Name: "+customer.getName());
System.out.println("Address: "+customer.getAddress());
System.out.println("Phone Number: "+customer.getNumber());
System.out.println("Customer Number: "+customer.getCustomerNumber());
System.out.println("Recieve Mail?: "+customer.getRecieveMail());
System.out.println("Amount Purchased: "+customer.getcustomerPurchase());
customer.setcustomerDiscount(customerPurchase);
System.out.println("Percent off: "+ customer.getcustomerDiscount());
}
}
Hope it helps...

I think it is a logical problem. Simply order the discount formula in reverse.
Catch the big numbers first:
if r >= 2000 print 10%
else if r >= 1500 print 7%
else if r >= 1000 print 6%
else if r >= 500 print 5%
else print nothing
I hope that helps you

Java Program Unable to receive the input and program terminated prematurely

I'm not sure y this coding is not receiving the input for the adjust variable and gets terminated before it runs completely
public class Question {
int id;
String name;
String type;
double amt;
public Question(int id, String name, String type, double amt) {
this.id = id;
this.name = name;
this.type = type;
this.amt = amt;
}
public static void main(String[] args)
{ }
}
import java.util.*;
public class Answer {
public static void gettype(Question[] q,String adjust)
{
for(int i=0;i<2;i++)
{
if(q[i].getType()==adjust)
{
System.out.println(q[i].getId());
}
}}
public static void main(String[] args) {
int id;
String name,type,adjust;
double amt;
Scanner s=new Scanner(System.in);
Answer a=new Answer();
System.out.println("enter 2 car inputs");
Question[] q=new Question[2];
for(int i=0;i<2;i++)
{
id=s.nextInt();
s.nextLine();
name=s.nextLine();
type=s.nextLine();
amt=s.nextDouble();
q[i]= new Question(id,name,type,amt);
}
adjust=s.nextLine();
a.gettype(q,adjust);
}
}
While running the code i am able to get the inputs for the car object array.But after that i am not able to get the values for the variable adjust.
So please need help with this one.
I have tried simply to print the objects at the constructor side.
But not able to receive the 9th input which will be assigned to the var adjust

I think this is better. You should understand why mine works.
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Question {
private int id;
private String name;
private String type;
private double amt;
Question(int id, String name, String type, double amt) {
this.id = id;
this.name = name;
this.type = type;
this.amt = amt;
}
int getId() {
return id;
}
String getName() {
return name;
}
String getType() {
return type;
}
double getAmt() {
return amt;
}
#Override
public String toString() {
final StringBuffer sb = new StringBuffer("Question{");
sb.append("id=").append(id);
sb.append(", name='").append(name).append('\'');
sb.append(", type='").append(type).append('\'');
sb.append(", amt=").append(amt);
sb.append('}');
return sb.toString();
}
}
class Answer {
public static final int NUM_QUESTIONS = 2;
public static void main(String[] args) {
int numQuestions = (args.length > 0) ? Integer.valueOf(args[0]) : NUM_QUESTIONS;
List<Question> questions = new ArrayList<>();
Scanner s = new Scanner(System.in);
for (int i = 0; i < numQuestions; ++i) {
System.out.println(String.format("Question %d", i));
System.out.print("id: ");
int id = s.nextInt();
System.out.print("name: ");
String name = s.next();
System.out.print("type: ");
String type = s.next();
System.out.print("amt: ");
double amt = s.nextDouble();
questions.add(new Question(id, name, type, amt));
}
System.out.println(questions);
}
}

How to sort ArrayList Java

I have this arrayList that i need to first sort from greatest to least by both item price and then after i need to sort it by the amount of items sold. Whats the easiest way to accomplish this? thanks!
import java.util.*;
public class salesPerson {
//salesPerson fields
private int salespersonID;
private String salespersonName;
private String productType;
private int unitsSold = 0;
private double unitPrice;
//Constructor method
public salesPerson(int salespersonID, String salespersonName, String productType, int unitsSold, double unitPrice)
{
this.salespersonID = salespersonID;
this.salespersonName = salespersonName;
this.productType = productType;
this.unitsSold = unitsSold;
this.unitPrice = unitPrice;
}
//Accessor for salesPerson
public int getSalesPersonID()
{
return salespersonID;
}
public String getSalesPersonName()
{
return salespersonName;
}
public String getProductType()
{
return productType;
}
public int getUnitsSold()
{
return unitsSold;
}
public double getUnitPrice()
{
return unitPrice;
}
public double getTotalSold()
{
return unitsSold * unitPrice;
}
//Mutoators for salesPerson
public void setSalesPersonID(int salespersonID)
{
this.salespersonID = salespersonID;
}
public void setSalesPersonName(String salespersonName)
{
this.salespersonName = salespersonName;
}
public void setProductType(String productType)
{
this.productType = productType;
}
public void setUnitsSold(int unitsSold)
{
this.unitsSold += unitsSold;
}
public void setUnitProce(double unitPrice)
{
this.unitPrice = unitPrice;
}
public static void main(String[] args)
{
ArrayList<salesPerson> salesPeople = new ArrayList<salesPerson>();
Scanner userInput = new Scanner(System.in);
boolean newRecord = true;
boolean showReport = true;
do
{
int salespersonID;
String salespersonName;
String productType;
int unitsSold = 0;
double unitPrice;
System.out.println("Please enter the Salesperson Inoformation.");
System.out.print("Salesperson ID: ");
salespersonID = userInput.nextInt();
System.out.print("Salesperson Name: ");
salespersonName = userInput.next();
System.out.print("Product Type: ");
productType = userInput.next();
System.out.print("Units Sold: ");
unitsSold = userInput.nextInt();
System.out.print("Unit Price: ");
unitPrice = userInput.nextDouble();
if(salesPeople.size() == 0)
{
salesPerson tmp = new salesPerson(salespersonID, salespersonName, productType, unitsSold, unitPrice);
salesPeople.add(tmp);
}
else
{
for(int i=0; i < salesPeople.size(); i++)
{
if(salesPeople.get(i).getSalesPersonID() == salespersonID)
{
salesPeople.get(i).setUnitsSold(unitsSold);
break;
}
else
{
salesPerson tmp = new salesPerson(salespersonID, salespersonName, productType, unitsSold, unitPrice);
salesPeople.add(tmp);
break;
}
//System.out.println(salesPeople.get(i).getSalesPersonName());
}
}
System.out.print("Would you like to enter more data?(y/n)");
String askNew = userInput.next();
newRecord = (askNew.toLowerCase().equals("y")) ? true : false;
}
while(newRecord == true);

Write a custom comparator:
public SalesPersonComparator implements Comparator<salesPerson> {
public int compare(final salesPerson p1, final salesPerson p2) {
// get the comparison of the unit prices (in descending order, so compare p2 to p1)
int comp = new Double(p2.getUnitPrice()).compareTo(new Double(p1.getUnitPrice()));
// if the same
if(comp == 0) {
// compare the units sold (in descending order, so compare p2 to p1)
comp = new Integer(p2.getUnitsSold()).compareTo(new Integer(p1.getUnitsSold()));
}
return comp;
}
}
Edit (thanks to #Levenal):
Then use Collections.sort() to sort your list.

How can I fix this null pointer exception?

I keep getting a nullPointerException and the rest of my code won't run. I have two classes setup. One is the SalesPerson and the other contains the main method. Line 42 is marked and that is where the nullPointerException occurs.
This is line 42
System.out.printf("%-20s %15.2f %14.2f %n", list[i].getFirstName() + " " + list[i].getLastName(), list[i].getTotalSales(), list[i].getSalary());
public class SalesPerson {
private String firstName;
private String lastName;
private double firstSales;
private double secondSales;
private double thirdSales;
private double fourthSales;
private double totalSales;
private double salary;
public SalesPerson(String lastName, String firstName, double firstSales,
double secondSales, double thirdSales, double fourthSales,
double totalSales, double salary) {
this.lastName = lastName;
this.firstName = firstName;
this.firstSales = firstSales;
this.secondSales = secondSales;
this.thirdSales = thirdSales;
this.fourthSales = fourthSales;
this.totalSales = totalSales;
this.salary = salary;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
public double getTotalSales() {
return totalSales;
}
public void setTotalSales(double totalSales) {
this.totalSales = totalSales;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public double getFirstSales() {
return firstSales;
}
public void setFirstSales(double firstSales) {
if (firstSales >= 0) {
this.firstSales = firstSales;
} else {
System.out.println("First sales must be greater than zero.");
}
}
public double getSecondSales() {
return secondSales;
}
public void setSecondSales(double secondSales) {
if (secondSales >= 0) {
this.secondSales = secondSales;
} else {
System.out.println("Second sales must be greater than zero.");
}
}
public double getThirdSales() {
return thirdSales;
}
public void setThirdSales(double thirdSales) {
if (thirdSales >= 0) {
this.thirdSales = thirdSales;
} else {
System.out.println("Third sales must be greater than zero.");
}
}
public double getFourthSales() {
return fourthSales;
}
public void setFourthSales(double fourthSales) {
if (fourthSales >= 0) {
this.fourthSales = fourthSales;
} else {
System.out.println("Fourth sales must be greater than zero.");
}
}
}
SECOND CLASS
import java.io.File;
import java.util.Scanner;
public class Assignment10 {
public static final int NUM_SALESPEOPLE = 20;
public static final double NUM_PER_SALARY = 25;
public static void main(String[] args) {
SalesPerson[] list = new SalesPerson[NUM_SALESPEOPLE];
try {
int people = 0;
Scanner fileInput = new Scanner(new File("A10.txt"));
while (fileInput.hasNext()) {
String lastName = fileInput.next();
String firstName = fileInput.next();
double firstSales = fileInput.nextDouble();
double secondSales = fileInput.nextDouble();
double thirdSales = fileInput.nextDouble();
double fourthSales = fileInput.nextDouble();
double totalSales = firstSales + secondSales + thirdSales + fourthSales;
double salary = NUM_PER_SALARY * totalSales;
SalesPerson person = new SalesPerson(lastName, firstName,
firstSales, secondSales, thirdSales, fourthSales, totalSales, salary);
list[people] = person;
people++;
}
} catch (Exception ex) {
System.out.println("Error opening file.");
}
System.out.println("Full Name Total Sales Salary");
System.out.println("========= =========== ======");
for (int i = 0; i < NUM_SALESPEOPLE; i++) {
System.out.printf("%-20s %15.2f %14.2f %n", list[i].getFirstName() + " " + list[i].getLastName(), list[i].getTotalSales(), list[i].getSalary());
}
System.out.println("===================================================");
}
}

You are creating an array of size 20. This array will hold only references to NULL. If in your file you have less than 20 entries you will end up with a nullpointerexception.
To be sure, try to print the value of people. If it less than 20 then this is normal.

Your file 'A10.txt' doesn't have 20 (correct) lines.
You should not create an Array. Use ArrayList and Iterator instead and you won't have such problems.

Simply add a check for null:
for (int i = 0; i < NUM_SALESPEOPLE; i++) {
if (list[i] != null) {
System.out.printf("%-20s %15.2f %14.2f %n", list[i].getFirstName() + " " + list[i].getLastName(), list[i].getTotalSales(), list[i].getSalary());
}
}
or declare
int people = 0;
two lines earlier (before your try-block) and use this number of actual read people as the upper bound in your for loop instead of NUM_SALESPEOPLE.