Develop Reference

Java NullPointerException why is the array null?

I can output the details from the student, but always when i do it displays
Exception in thread "main" java.lang.NullPointerException
at client.Client.main(Client.java:126)
and the program crashes.
The array is null , I don't why and I don't know how to fix that. Please help me to understand, the problem should be around here..
if (choice == 3) {
for (int a = 0; a < list.length; a++) { //To Display all current Student Information.
// list[i] = new student();
list[a].DisplayOutput();
}
Anyways here comes my code.
package client;
import java.util.Scanner;
public class Client {
//my infos
public static void AuthorInformation() {
System.out.print("__________________________________________\n"
+ "Student Name: xxxxxx xxxxxx\n"
+ "Student ID-Number: xxxxxx\n"
+ "Tutorial Timing: Wednesday 9:30 - 12:30 \n"
+ "Tutor Name: Mr xxxxxx\n\n"
+ "__________________________________________\n");
}
This is my client Class
public static void main(String[] args) {
AuthorInformation(); //calls the method for my information
student[] list = new student[20]; //my array
student student = new student();
int choice = 0; //variable for the choise of the menu
Scanner keyboard = new Scanner(System.in); //Scanner class
do { //MY menu in the do-while, so that it runs at least once while user enters 7(quit)
student.DisplayQuestions();
choice = keyboard.nextInt(); //takes the entered value from the user
if (choice == 1) {
System.out.println("Enter the Number of Students you want to store: ");//Enter amount of students to be stored
int studentNumber = keyboard.nextInt();
// student.addStudent();
for (int i = 0; i < studentNumber; i++) { //for loop is till the student number is achieved
list[i] = new student();
System.out.println("\nTitle of the student (eg, Mr, Miss, Ms, Mrs etc): ");
list[i].SetTitle(keyboard.next());
System.out.println("First name (given name)");
list[i].SetFirstName(keyboard.next());
System.out.println("A last name (family name/surname)");
list[i].SetFamilyName(keyboard.next());
System.out.println("Student number (ID):");
list[i].SetStudentID(keyboard.nextInt());
System.out.println("Enter the Day of birth(1-31): ");
list[i].SetDay(keyboard.nextInt());
System.out.println("Enter the Month of birth (1-12): ");
list[i].SetMonth(keyboard.nextInt());
System.out.println("Enter The Year of birth: ");
list[i].SetYear(keyboard.nextInt());
System.out.println("Students First Assignment Mark (0 - 100): ");
list[i].SetFirstMark(keyboard.nextInt());
System.out.println("Students Second Assignment Mark (0 - 100): ");
list[i].SetSecondMark(keyboard.nextInt());
System.out.println("Enter the mark of Student weekly practical work (0-10) ");
list[i].SetWeeklyMarks(keyboard.nextInt());
System.out.println("Please Enter the Marks for the final Exam(0 - 100): ");
list[i].SetFinalMark(keyboard.nextInt());
/* System.out.println("- - - - - - - - - - - - -");
System.out.println("Do you want to add another Student? (Yes/No)");
String a = keyboard.next();
if (a.equalsIgnoreCase("yes")) {
} else if (a.equalsIgnoreCase("no")) {
i = list.length + 1;
}*/
}
}
if (choice == 2) {
int x = 2;
double AverageNum = 0;
for (int p = 0; p < x; p++) { //This is to take the Average OverallMarks of all students
AverageNum += list[p].OverallMarking();
}
System.out.println("Total Average Of Overall Marks is :" + AverageNum / 2);
}
if (choice == 3) {
for (int a = 0; a < list.length; a++) { //To Display all current Student Information.
// list[i] = new student();
list[a].DisplayOutput();
}
}
if (choice == 4) { //To Display the distribution of grades awarded.
System.out.println("\nGrade Distribution: \n" + student.GetCounterHD() + " HDs\n" + student.GetCounterD() + " Ds\n" + student.GetCounterC() + " Cs\n" + student.GetCounterP() + " Ps\n" + student.GetCounterN() + " Ns\n");
}
if (choice == 5) {
System.out.println("Enter Student's ID Number to search for: "); // to take the id number from the user
int FindID = keyboard.nextInt();
boolean Found = false;
// to find with the student ID Number details of the student.
for (int i = 0; i < 10; i++) {
if (FindID == list[i].GetStudentID()) {
list[i].DisplayOutput();
Found = true;
break;
}
}
}
if (choice == 6) { //
System.out.println("Enter Student's Name to search for: ");
String SearchStudentName = keyboard.next(); //take the name of the student
boolean Found = false;
//To find the name of the student it loops till it has it or the limit of studentnumbers are achieved.
for (int i = 0; i < list.length; i++) {
if (SearchStudentName.equalsIgnoreCase(list[i].GetFirstName())) {
list[i].DisplayOutput();
Found = true;
break;
}
}
}
} while (choice != 7);
{ //while statement quit the program
System.out.println("\nYou Quit.");
}
}
}
And here is my student class
package client;
import java.util.Scanner;
public class student {
//The instance vriables for students (Title, first name, family name,
Student ID, date of birth in day month and year, first and second
assignment mark, mark of weekly practical work and final exam
private String Title;
private String FirstName;
private String FamilyName;
private long StudentID;
private int Day;
private int Month;
private int Year;
private float FirstMark;
private float SecondMark;
private float WeeklyMarks;
private float FinalMark;
//those private instance variables are for the calculation of (first and
second assignment mark, mark of weekly practical work and exam mark, final
mark and overall mark)
private float FirstMarkPercentage;
private float SecondMarkPercentage;
private float WeeklyMarksPercentage;
private float ExamPercentage;
private String FinalGrade;
private float OverallMarks = 0;
//those private instance variables are to count the the marks(
private int CounterN = 0;
private int CounterP = 0;
private int CounterC = 0;
private int CounterD = 0;
private int CounterHD = 0;
public student(String Title, String FirstName, String FamilyName, long StudentID, int Day, int Month, int Year, float FirstMark, float SecondMark, float WeeklyMarks, float FinalMark) {
this.Title = Title;
this.FirstName = FirstName;
this.FamilyName = FamilyName;
this.StudentID = StudentID;
this.Day = Day;
this.Month = Month;
this.Year = Year;
this.FirstMark = FirstMark;
this.SecondMark = SecondMark;
this.WeeklyMarks = WeeklyMarks;
this.FinalMark = FinalMark;
this.FinalGrade = FinalGrade;
}
//This Method is to display (Title, first name, family name, Student ID, date of birth in day month and year, first and second assignment mark, mark of weekly practical work and final exam)
public student() {
Title = "";
FirstName = "";
FamilyName = "";
StudentID = 0;
Day = 0;
Month = 0;
Year = 0;
FirstMark = 0;
SecondMark = 0;
WeeklyMarks = 0;
FinalMark = 0;
}
//The methods starting with Get...(), are to return the (Title, first name, family name, Student ID, date of birth in day month and year, first and second assignment mark, mark of weekly practical work and final exam and the marks N, P, C, D & HD)
public String GetTitle() {
return Title;
}
public String GetFirstName() {
return FirstName;
}
public String GetFamilyName() {
return FamilyName;
}
public long GetStudentID() {
return StudentID;
}
public int GetDay() {
return Day;
}
public int GetMonth() {
return Month;
}
public int GetYear() {
return Year;
}
public float GetFirstMark() {
return FirstMark;
}
public float GetSecondMark() {
return SecondMark;
}
public float GetWeeklyMarks() {
return WeeklyMarks;
}
public float GetFinalMark() {
return FinalMark;
}
public String GetFinalGrade() {
return FinalGrade;
}
public int GetCounterHD() {
return CounterHD;
}
public int GetCounterD() {
return CounterD;
}
public int GetCounterC() {
return CounterC;
}
public int GetCounterP() {
return CounterP;
}
public int GetCounterN() {
return CounterN;
}
public float GetOverallMarks() {
return OverallMarks;
}
//The methods starting with Set...(), are to set the (Title, first name, family name, Student ID, date of birth in day month and year, first and second assignment mark, mark of weekly practical work and final exam and the marks N, P, C, D & HD)
public void SetTitle(String Title) {
this.Title = Title;
}
public void SetFirstName(String FirstName) {
this.FirstName = FirstName;
}
public void SetFamilyName(String FamilyName) {
this.FamilyName = FamilyName;
}
public void SetStudentID(int StudentID) {
this.StudentID = StudentID;
}
public void SetDay(int Day) {
this.Day = Day;
}
public void SetMonth(int Month) {
this.Month = Month;
}
public void SetYear(int Year) {
this.Year = Year;
}
public void SetFirstMark(float FirstMark) {
this.FirstMark = FirstMark;
}
public void SetSecondMark(float SecondMark) {
this.SecondMark = SecondMark;
}
public void SetWeeklyMarks(float WeeklyMarks) {
this.WeeklyMarks = WeeklyMarks;
}
public void SetFinalMark(float FinalMark) {
this.FinalMark = FinalMark;
}
public void SetFinalGrade(String FinalGrade) {
this.FinalGrade = FinalGrade;
}
public void SetOverallMarks(float OverallMarks) {
this.OverallMarks = OverallMarks;
}
public boolean equals(student OtherStudent) {
return (this.FirstName.equalsIgnoreCase(OtherStudent.FirstName)) && (this.FamilyName.equalsIgnoreCase(OtherStudent.FamilyName));
}
//this method is for the calculation of (first and second assignment mark, mark of weekly practical work and exam mark, final mark and overall mark)
public float OverallMarking() {
FirstMarkPercentage = ((FirstMark / 100) * 20);
SecondMarkPercentage = ((SecondMark / 100) * 20);
WeeklyMarksPercentage = ((WeeklyMarks / 10) * 10);
ExamPercentage = ((FinalMark / 100) * 50);
OverallMarks = FirstMarkPercentage + SecondMarkPercentage + WeeklyMarksPercentage + ExamPercentage; //for the overall mark returns
return OverallMarks;
}
//this function arranges the grade calculations and returns the final grade
public String GradeCalculations() {
if (OverallMarks >= 80 && OverallMarks <= 100) { // if grade lies within this range print HD
FinalGrade = "HD";
CounterHD++;
} else if (OverallMarks >= 70 && OverallMarks < 80) { // if grade lies within this range print D
FinalGrade = "D";
CounterD++;
} else if (OverallMarks >= 60 && OverallMarks < 70) { // if grade lies within this range print C
FinalGrade = "C";
CounterC++;
} else if (OverallMarks >= 50 && OverallMarks < 60) { // if grade lies within this range print P
FinalGrade = "P";
CounterP++;
} else if (OverallMarks < 50 && OverallMarks >= 0) { // if grade lies within this range print N
FinalGrade = "N";
CounterN++;
}
return FinalGrade;
}
public void DisplayQuestions() {
System.out.println("\n Welcome to the Menu to perform one of the following operations (You must enter a number between 1-7):");
System.out.println("(1) To add the Student Information.");
System.out.println("(2) To Display the Output from the Average Overall Mark for students.");
System.out.println("(3) To Display all current Student Information.");
System.out.println("(4) To Display the distribution of grades awarded.");
System.out.println("(5) for entering a student ID Number To view all details of the student.");
System.out.println("(6) for entering a student name To view all details of the student.");
System.out.println("(7) Quit");
System.out.println("\n__________________________________________");
}
//This function displays the details of the student with before calculated marks.
public void DisplayOutput() {
System.out.println("\nName: " + GetTitle() + " " + GetFirstName() + " " + GetFamilyName());
System.out.println("Student ID: " + GetStudentID());
System.out.println("Date of Birth: " + GetDay() + "/" + GetMonth() + "/" + GetYear());
System.out.println("Assignment 1 Marks: " + GetFirstMark());
System.out.println("Assignment 2 Marks: " + GetSecondMark());
System.out.println("Weekly Practical Marks: " + GetWeeklyMarks());
System.out.println("Final Exam Marks: " + GetFinalMark());
System.out.println("Final Marks & Grade: " + OverallMarking() + "/" + GradeCalculations());
}
public void addStudent() {
/*Scanner keyboard = new Scanner(System.in);
for (int i = 0; i < list.length; i++) { //for loop is till the student number is achieved
list[i] = new student();
System.out.println("\nTitle of the student (eg, Mr, Miss, Ms, Mrs etc): ");
list[i].SetTitle(keyboard.next());
System.out.println("First name (given name)");
list[i].SetFirstName(keyboard.next());
System.out.println("A last name (family name/surname)");
list[i].SetFamilyName(keyboard.next());
System.out.println("Student number (ID):");
list[i].SetStudentID(keyboard.nextInt());
System.out.println("Enter the Day of birth(1-31): ");
list[i].SetDay(keyboard.nextInt());
System.out.println("Enter the Month of birth (1-12): ");
list[i].SetMonth(keyboard.nextInt());
System.out.println("Enter The Year of birth: ");
list[i].SetYear(keyboard.nextInt());
System.out.println("Students First Assignment Mark (0 - 100): ");
list[i].SetFirstMark(keyboard.nextInt());
System.out.println("Students Second Assignment Mark (0 - 100): ");
list[i].SetSecondMark(keyboard.nextInt());
System.out.println("Enter the mark of Student weekly practical work (0-10) ");
list[i].SetWeeklyMarks(keyboard.nextInt());
System.out.println("Please Enter the Marks for the final Exam(0 - 100): ");
list[i].SetFinalMark(keyboard.nextInt());
System.out.println("- - - - - - - - - - - - -");
System.out.println("Do you want to add another Student? (Yes/No)");
String a = keyboard.next();
if (a.equalsIgnoreCase("yes")) {
addStudent();
} else if (a.equalsIgnoreCase("no")) {
i=list.length+1;
}
}*/
}
}

The array isn't null.
The exception is thrown when you try to call a method on a null member of the array.
You iterate over the full array, but have not necessarily filled the entire array. Members that you have not assigned to reference an object are null.
for (int a = 0; a < list.length; a++) { //To Display all current Student Information.
// list[i] = new student();
list[a].DisplayOutput();
}
One fix would be to stop iterating after you've hit the first null.
for (int a = 0; a < list.length; a++) { //To Display all current Student Information.
// list[i] = new student();
student student = list[a];
if ( null == student ) {
break;
}
else {
list[a].DisplayOutput();
}
}
Another fix would be to remember in case 1 how many students were stored, and change the loop condition to reflect that.
for (int a = 0; a < cntStudents; a++) { //To Display all current Student Information.
By the way, in Java code it is almost universally accepted that:
Class names begin with an uppercase character.
Method names begin with a lowercase character.

can not be assigned to a variable error in eclipse (homework)

I am building on a ordering program for java for a class in school and I am getting quantityInput can not be resolved to a variable error I also get the error
the method showInputDialog(Component, Object, Object) in the type JOptionPane is not applicable for the arguments (String, int, int)
any help in resolving the 2 errors would be much aprecated.
/**
* Course: IT110 - Introduction to Programming
* Filename: KagesKreationsPhase1.java
* Created: 04/09/10 by Dr. Debby Telfer
* Modified: 11/26/13 by Dr. Bary W Pollack
*
* Purpose: Created a simple online ordering system
* for Pizzas-R-Us customers
*/
import javax.swing.JOptionPane;
import java.io.*;
import java.util.Scanner;
/**
* #author bary
*/
public class KagesKreations {
/**
* #param args
*/
public static void main(String[] args) {
// declare variables
String openingMsg, nameInputMsg, customerName, nameOutputMsg, getReturning, getColor, getQuantity,
returnInputMsg, customerReturn, returnOutputMsg, quantityMsg, quantityOutputMsg, totalOutputMsg,
colorChoiceMsg, colorChoice, colorChoiceOutputMsg, greetingOutputMsg, outputMsg, quantityInput, getname;
int number = 0;
double cost = 10.00;
double taxRate = 1.07;
double total;
try {
// display opening message
openingMsg = "*** Welcome to Kage's Kreations Online Ordering System ***\n"
+ " Lets Pick A Kustiom Kreation!";
JOptionPane.showMessageDialog(null, openingMsg);
// get required input using dialogs
customerName = getName();
customerReturn = getReturning();
colorChoice = getColor();
quantityInput = getQuantity();
number = Integer.parseInt(quantityInput);
KagesKreations.totalCost(number, cost, taxRate);
total = totalCost(number, cost, taxRate);
writeOrderFile(customerName, customerReturn, colorChoice,quantityInput, total);
confirmation();
}
catch (Exception e) {
JOptionPane.showMessageDialog(null, e.getMessage());
System.exit(1);
}
} // end main()
public static String getStringInput(String prompt) throws Exception {
String value;
int i = 0;
do {
value = JOptionPane.showInputDialog(prompt);i++;
if (value == null) {
throw new Exception("Cancle was pressed. Closeing the program.");
}
} while (value.equals("") && i < 3);
if (value.equals("")) {
throw new Exception("No input vale was entered after three attempts.");
}
return value;
}
public static int getQuantity(int lowValue, int highValue) throws Exception {
// quantity must be between 1-99
int quantity;
int counter = 0;
int quantityInput;
do {
quantityInput = Integer.parseInt(JOptionPane.showInputDialog("How many bracelets would you like to order? (1-99)", 1, 99));
counter = counter + 1;
} while (quantityInput < lowValue || quantityInput > highValue && counter < 3);
if (quantityInput < lowValue || quantityInput > highValue) {
throw new Exception("Invalid responce please enter a number between 1 and 99");
}
quantity = quantityInput;
return quantity;
}
public static String getColor() throws Exception {
String color;
int counter = 0;
do {
color = JOptionPane.showInputDialog("Please choose Brown or Black for the color of your bracelet");
counter = counter + 1;
} while (!color.equals("Brown") && !color.equals("Black") && counter < 3);
if (!color.equals("Brown") && !color.equals("Black")) {
throw new Exception("Invalid responce please enter Brown or Black.");
}
return color;
}
public static String getReturning() throws Exception {
String returning;
int counter = 0;
do {
returning = JOptionPane.showInputDialog("Are you a returning customer? (Yes or No)");
counter = counter +1;
} while (!returning.equals("Yes") && !returning.equals("No") && counter < 3 );
if (!returning.equals("Yes") && !returning.equals("No")) {
throw new Exception("Invalid responce please enter Yes or No.");
}
return returning;
}
public static String getName() throws Exception {
String name;
int counter = 0;
do {
name = JOptionPane.showInputDialog("Please Enter your name.");
counter = counter + 1;
} while (counter < 3);
return name;
}
public static double totalCost(int number, double cost, double taxRate){
double total = 0;
total = (number * cost) * taxRate;
return total;
}
public static void writeOrderFile(String name, String returning, String color, String quantity, double total) throws Exception {
File order = new File("order.tx");
PrintWriter pw = new PrintWriter(order);
pw.println(name);
pw.println(returning);
pw.println(color);
pw.println(quantity);
pw.println(total);
pw.close();
}
public static void confirmation() throws Exception{
String nameOutputMsg, customerName, returnOutputMsg, customerReturn, colorChoiceOutputMsg, colorChoice, quantityOutputMsg, quantityInput,
totalOutputMsg, total, greetingOutputMsg, outputMsg;
FileReader fr = new FileReader("order.txt");
BufferedReader bf = new BufferedReader(fr);
customerName = bf.readLine();
customerReturn = bf.readLine();
colorChoice = bf.readLine();
quantityInput = bf.readLine();
total = bf.readLine();
fr.close();
// build output strings
nameOutputMsg = "Welcome " + customerName + ".\n\n";
returnOutputMsg = "Your return customer status is " + customerReturn + ".\n";
colorChoiceOutputMsg = "You have chosen " + colorChoice + " as the color for your braclet.\n";
quantityOutputMsg = "You have ordered " + quantityInput + " bracelets.\n";
totalOutputMsg = "Your total cost is $" + total + ".\n";
greetingOutputMsg = "Thank you for visiting Kage's Kreations!" + "\n\n"
+ "Your order should ships in 24 to 48 hours.\n";
// create and display output string
outputMsg = nameOutputMsg + returnOutputMsg + colorChoiceOutputMsg + quantityOutputMsg + totalOutputMsg + greetingOutputMsg;
JOptionPane.showMessageDialog(null, outputMsg);
}
} // end class KagesKreationsPhase1

The second prolem is that JOptionPane just does not provide any method that matches the arguments you try to pass in your getQuantity-mehod:
quantityInput = Integer.parseInt(JOptionPane.showInputDialog("How many bracelets would you like to order? (1-99)", 1, 99));
You have to chose one of the existing methods.

You should declare a variable before using it. You can declare the variable inside the getQuantity() or in class level (Please read much about local and class variables). you can declare it as the way you declared quantity and counter variables.
public static int getQuantity(int lowValue, int highValue) throws Exception {
// quantity must be between 1-99
int quantity;
int counter = 0;
int quantityInput = 0;
...
}
In your code I can't find a place where you are using showInputDialog() with String, int, int parameters. Please share the full code your trying.

I'm trying to do stuff with inheritance but none of it will work

Im trying to get different variables from loan but none of them ever get to loan.java. My inheritance goes from Loan.Java > BusinessLoan.java > CreateLoan.java. I can get a variable from CreateLoan to display in business but when I set it in business I can't grab it. And I know some of this stuff is stupid but this is my final so some of the stuff was required. Heres my code
Loan.java
package Construction;
public class Loan implements LoanConstant{
public static int loanNumber;
public static String lastName;
public static int loanAmount;
public static int interestRate;
public static int term;
public int primeRate;
public int getLoanNumber() { return loanNumber; }
public void setLoanNumber(int n) { n = loanNumber; }
public String getLastName() { return lastName; }
public void setLastName(String s) { s = lastName; }
public int getLoanAmount() { return loanAmount; }
public void setLoanAmount(int n) {
n = loanAmount;
if (loanAmount > MAX_LOAN_AMOUNT)
loanAmount = MAX_LOAN_AMOUNT;
}
public int getTerm() { return term; }
public void setTerm(int n) {
n = term;
if (term == 1) {
term = SHORT_TERM;
} else if (term == 3) {
term = MEDIUM_TERM;
} else if(term == 5) {
term = LONG_TERM;
} else
term = SHORT_TERM;
}
public int getInterestRate() { return interestRate; }
public void setInterestRate(int i) { i = interestRate; }
public static void displayAll() {
System.out.println("The Company's Name is " + COMPANY_NAME);
System.out.println("The loan number is " + loanNumber);
System.out.println("The last name on the loan is " + lastName);
System.out.println("The loan amount is " + loanAmount);
System.out.println("The interest rate on the loan is " + interestRate);
System.out.println("The term on the account is " + term);
}
}
PersonalLoan.java
package Construction;
public class PersonalLoan extends Loan{
public PersonalLoan(int ln, String last, int la, int term) {
setLoanNumber(ln);
setLastName(last);
setLoanAmount(la);
setTerm(term);
interestRate = (int)((primeRate * 0.02) + primeRate);
setInterestRate(interestRate);
}
}
BusinessLoan.java
package Construction;
public class BusinessLoan extends Loan{
public BusinessLoan(int ln, String last, int la, int term) {
setLoanNumber(ln);
setLastName(last);
setLoanAmount(la);
setTerm(term);
interestRate = (int)((primeRate * 0.01) + primeRate);
setInterestRate(interestRate);
}
}
CreateLoan.java
package Construction;
import java.util.Scanner;
public class CreateLoan {
public static void main(String[] args) {
int x = 0;
int primeRate;
String type;
Scanner input = new Scanner(System.in);
Loan[] loans = new Loan[5];
System.out.println("Please enter the prime interest rate");
primeRate = input.nextInt();
primeRate = primeRate/100;
input.nextLine();
for(x = 0; x < 6; ++x) {
System.out.println("Please enter a loan type. Choose either Business or Personal. If you don't type it like that you'll get an error.");
type = input.nextLine();
if (type.equalsIgnoreCase("Business")) {
System.out.println("What is the account number on the loan?");
int ln = input.nextInt();
System.out.println("What is the last name on the account?");
String last = input.nextLine();
input.nextLine();
System.out.println("What is the loan amount? If you put more then 100k it'll only accept up to 100k");
int la = input.nextInt();
System.out.println("What is the term on the account? If you enter something other then 1, 3, or 5 it will default to a short term.");
int term = input.nextInt();
loans[x] = new BusinessLoan(ln, last, la, term);
System.out.println("The Company's Name is " + Loan.COMPANY_NAME);
System.out.println("The loan number is " + loans[x].getLoanNumber());
System.out.println("The last name on the loan is " + loans[x].getLastName());
System.out.println("The loan amount is " + loans[x].getLoanAmount());
System.out.println("The interest rate on the loan is " + loans[x].getInterestRate());
System.out.println("The term on the account is " + loans[x].getTerm());
}
else if (type.equalsIgnoreCase("Personal")) {
System.out.println("What is the account number on the loan?");
int ln = input.nextInt();
System.out.println("What is the last name on the account?");
String last = input.nextLine();
input.nextLine();
System.out.println("What is the loan amount? If you put more then 100k it'll only accept up to 100k");
int la = input.nextInt();
System.out.println("What is the term on the account? If you enter something other then 1, 3, or 5 it will default to a short term.");
int term = input.nextInt();
loans[x] = new PersonalLoan(ln, last, la, term);
System.out.println("The Company's Name is " + Loan.COMPANY_NAME);
System.out.println("The loan number is " + loans[x].getLoanNumber());
System.out.println("The last name on the loan is " + loans[x].getLastName());
System.out.println("The loan amount is " + loans[x].getLoanAmount());
System.out.println("The interest rate on the loan is " + loans[x].getInterestRate());
System.out.println("The term on the account is " + loans[x].getTerm());
} else {
System.out.println("You've entered an invalid type. Please restart and try again.");
System.exit(0);
}
}
}
}
LoanConstants.java
package Construction;
public interface LoanConstant {
public final static int SHORT_TERM = 1;
public final static int MEDIUM_TERM = 3;
public final static int LONG_TERM = 5;
public final static String COMPANY_NAME = "Sanchez Construction";
public final static int MAX_LOAN_AMOUNT = 100000;
}

In addition to the Loan fields being static (remove the static). You should also update your setters.
public void setLoanNumber(int n) { n = loanNumber; }
public void setLastName(String s) { s = lastName; }
You are assigning the value to the passed in variable (not the field). Should be
public void setLoanNumber(int n) { loanNumber = n; }
public void setLastName(String s) { lastName = s; }
and
public void setTerm(int n) {
// n = term;
if (n == 1) {
term = SHORT_TERM;
} else if (n == 3) {
term = MEDIUM_TERM;
} else if (n == 5) {
term = LONG_TERM;
} else
term = SHORT_TERM;
}
public void setInterestRate(int i) { interestRate = i; }

Reading from a text file, checking for correct information, then displaying it

So I have successfully added a list of users with fake bank account information into a text file. Now I need someway to read them back into my program.
For example:
If I entered username - mattsmith
and PIN - 1234
The rest of Matt Smiths back account information would show up in the console, and I want to be able to do things like add money, check balance, and withdraw.
What would be the best way to approach this?
Here is the code that I have so far
ATM CLASS
public class ATM {
public static void main(String[] args) {
// variables
String dash = "-------------------\n";
int accounts = 0;
Bank bank = new Bank();
boolean login = true;
// Scanner
Scanner scanner = new Scanner(System.in);
// Welcome screen
System.out.print(dash);
System.out.print("Welcome to the Bank\n");
System.out.print(dash);
System.out.println("Do you have an account with us? (y/n) ");
String answer = scanner.nextLine();
if (answer.equalsIgnoreCase("y")) {
while (login) {
System.out.println("Username: ");
String lUsername = scanner.nextLine();
System.out.println("PIN: ");
int lPin = scanner.nextInt();
if (lUsername.equals(SampleUser.myUserName)
&& lPin == SampleUser.myPin) {
login = false;
System.out.println("\nLogin successful\n");
}
}
Bank.menu();
} else {
// new user is created
System.out.println("Enter your full name below (e.g. John M. Smith): ");
String name = scanner.nextLine();
System.out.println("Create a username: ");
String userName = scanner.nextLine();
System.out.println("Enter your starting deposit amount: ");
double balance = scanner.nextInt();
System.out.print(dash);
System.out.print("Generating your information...\n");
System.out.print(dash);
int pin = bank.PIN();
String accountNum = bank.accountNum();
User user = new User(name, userName, pin, accountNum, balance);
// new user gets added to the array list
Bank.users.add(user);
System.out.println(user);
}
try {
File file = new File("users.text");
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile(), true);
BufferedWriter bw = new BufferedWriter(fw);
bw.append(String.valueOf(Bank.users));
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
BANK CLASS
public class Bank {
// Generate a random 16 digit bank account number
public String accountNum() {
int max = 9999;
int min = 1000;
int a1 = (int) (Math.random() * (max - min) + min);
int a2 = (int) (Math.random() * (max - min) + min);
int a3 = (int) (Math.random() * (max - min) + min);
int a4 = (int) (Math.random() * (max - min) + min);
String accountNum = a1 + "-" + a2 + "-" + a3 + "-" + a4;
return accountNum;
}
// Generate a random 4 digit PIN
public int PIN() {
int max = 9999;
int min = 1000;
int PIN = (int) (Math.random() * (max - min) + min);
return PIN;
}
public static void menu() {
while (true) {
System.out.print("\n1"); System.out.print(" - View Balance ");
System.out.print("3"); System.out.print(" - Deposit Money\n");
System.out.print("2"); System.out.print(" - Withdraw Money ");
System.out.print("4"); System.out.print(" - Exit\n\n");
System.out.print("I would like to: \n");
Scanner bscanner = new Scanner(System.in);
int mc = bscanner.nextInt();
if (mc == 1) {
System.out.print("Your current balance is: $" + SampleUser.getMyBalance() + "\n");
} else if (mc == 2) {
System.out.print("Enter withdrawl amount: ");
double wd = bscanner.nextDouble();
SampleUser.myBalance -= wd;
System.out.println("\n$" + SampleUser.getMyBalance() + " is your new account total");
} else if (mc == 3) {
System.out.print("Enter deposit amount: ");
double dp = bscanner.nextDouble();
SampleUser.myBalance += dp;
System.out.println("\n$" + SampleUser.getMyBalance() + " is your new account total");
}
}
}
public static void readFile() {
}
// array list for users
static ArrayList users = new ArrayList(); {
};
}
USER CLASS
public class User implements Serializable{
String name;
String userName;
String accountNum;
int pin;
double balance;
public User (String name, String userName, int pin, String accountNum, double balance) {
this.name = name;
this.userName = userName;
this.accountNum = accountNum;
this.pin = pin;
this.balance = balance;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getAccountNum() {
return accountNum;
}
public void setAccountNum(String accountNum) {
this.accountNum = accountNum;
}
public int getPin() {
return pin;
}
public void setPin(int pin) {
this.pin = pin;
}
public double getBalance() {
return balance;
}
public void setBalance(double balance) {
this.balance = balance;
}
}
[1] http://prntscr.com/2jqm20

Java StringTokenizer and storing Array

I have programmed a Worker class and the driverclass for Worker..
My working class is compiling fine and showing the desired output..
But in array and StringTokenizer I am facing the main problem... And in line 32 of TestWorker.java there is an error, and I donot know why is it giving
The question is...
(i)Declare an array that can store the references of up to 5 Worker objects constructed with the data(name,workerID and hourlyRate).
(ii)And now allow the users to enter workerID and hours repeatedly until user enter an empty string. Read these values and invoke the method addWeekly() on the appropriate object (by searching through the array to locate the object with the specified ID). If a nonexistent ID is entered, display an appropriate error message.
(iii)Compute and display the salary for all the workers
Please see my codes below.....
//Worker.java
public class Worker {
public final double bonus=100;
protected String name, workerID;
protected double hourlyRate, totalHoursWorked,tax,grossSalary,netSalary;
public Worker(){
}
public Worker(String name, String workerID, double hourlyRate){
this.name = name;
this.workerID = workerID;
this.hourlyRate = hourlyRate;
}
public void addWeekly(double hoursWorked){
this.totalHoursWorked = this.totalHoursWorked + hoursWorked;
}
public double gross(){
grossSalary = (totalHoursWorked*hourlyRate);
if(totalHoursWorked>=150){
grossSalary = grossSalary +100;
}
return grossSalary;
}
public double netAndTax(){
netSalary = grossSalary;
if(grossSalary>500){
tax = (grossSalary - 500) *0.3;
netSalary = (grossSalary - tax);
}
return netSalary;
}
public String getName(){
return this.name;
}
public String getWorkerID(){
return this.workerID;
}
public double getHourlyRate(){
return this.hourlyRate;
}
public double getTotalHours(){
return totalHoursWorked;
}
public double getGrossSalary(){
return grossSalary;
}
public void addToGross(double amt){
grossSalary = grossSalary + amt;
}
public void displaySalary(){
System.out.print("Name: " +getName() + "\nID :" + getWorkerID()
+ "\nHourly Rate: " + getHourlyRate()+ "\nTotalHours Worked" + getTotalHours() +
"\nGross pay" + getGrossSalary() + "\nTax: " + netAndTax() +
"\nNet Pay: " + netAndTax());
}
}
//TestWorker.java
import java.util.Scanner;
import java.util.StringTokenizer;
public class TestWorker {
public static void main(String args[]){
Worker e = new Worker("John Major","s123",15.0);
e.addWeekly(45);
e.addWeekly(40);
e.addWeekly(32);
e.addWeekly(38);
e.gross();
e.netAndTax();
e.displaySalary();
Worker[] worklist = new Worker[5];
worklist[0] = new Worker("Richard Cooper","s1235",20.0);
worklist[1] = new Worker("John Major","s1236",18.0);
worklist[2] = new Worker("Mary Thatcher","s1237",15.0);
worklist[3] = new Worker("David Benjamin","s1238",16.0);
worklist[4] = new Worker("Jack Soo","s1239",25.0);
Scanner input = new Scanner(System.in);
String name;
double hourly;
do{
System.out.println("\n");
System.out.print("Please Enter ID and hours-worked in a given week: ");
name = input.nextLine();
StringTokenizer string = new StringTokenizer(name,"+");
String[] array =new String[(string.countTokens)];
for(int i=0;i<=4;i++){
if(array[0].equals(worklist[0])){
e.getName();
e.getWorkerID();
e.addWeekly(Double.parseDouble(array[0]));
e.gross();
e.displaySalary();
}
else if(array[0].equals(worklist[1])){
e.getName();
e.getWorkerID();
e.addWeekly(Double.parseDouble(array[1]));
e.gross();
e.displaySalary();
}
else if(array[0].equals(worklist[2])){
e.getName();
e.getWorkerID();
e.addWeekly(Double.parseDouble(array[2]));
e.gross();
e.displaySalary();
}
else if(array[0].equals(worklist[3])){
e.getName();
e.getWorkerID();
e.addWeekly(Double.parseDouble(array[3]));
e.gross();
e.displaySalary();
}
else if(array[0].equals(worklist[4])){
e.getName();
e.getWorkerID();
e.getHourlyRate();
e.addWeekly(Double.parseDouble(array[4]));
e.gross();
e.displaySalary();
}
else{
System.out.println("Please Enter correct information");
}
}
System.out.println();
while(string.hasMoreElements()){
System.out.println(string.nextElement());
}
}
while(name.isEmpty()==false);
}
}

Firstly, you've specified countTokens as a field when it is actually a method on this line:
String[] array = new String[(string.countTokens)]; // Incorrect
String[] array = new String[(string.countTokens())]; // Correct
Now you seem to be splitting the input on a + sign? So you're expected input is something along the lines of s123+12 which would mean ID s123 worked 12 hours this week. So in order to solve something like you probably want a loop that looks like this:
Scanner input = new Scanner(System.in);
System.out.println("\n");
System.out.print("Please Enter ID and hours-worked in a given week: ");
String enteredString = input.nextLine();
while (!enteredString.isEmpty()) {
StringTokenizer stringtok = new StringTokenizer(enteredString, "+");
String id = stringtok.nextToken();
Double hours = Double.parseDouble(stringtok.nextToken());
for (int i = 0; i < 5; i++) {
if (worklist[i].getWorkerID().equals(id)) {
worklist[i].addWeekly(hours);
break;
}
}
System.out.println("\n");
System.out.print("Please Enter ID and hours-worked in a given week: ");
enteredString = input.nextLine();
}
for (int i = 0; i < 5; i++) {
worklist[i].gross();
worklist[i].netAndTax();
worklist[i].displaySalary();
}
Keep in mind that this is very rough and I'm not entirely clear from your instructions on what exactly you are trying to achieve.

Why not consider String.split() name.split("\\+") that will give you a string array