Why does my program crash when i excute method "O"?

Why does my program crash when i excute method "O"? - java

package trainbooking;
import java.util.Scanner;
public class Trainbooking {
static final int SEATING_CAPACITY = 8;
public static void displayMenu() {
System.out.println("WELCOME TO OUR BOOKING SYSTEM");
System.out.println("A) Add a customer to seat");
System.out.println("V) View all the seats");
System.out.println("E) Display Empty seats");
System.out.println("D) Delete customer from seat");
System.out.println("F) Find the seat for a given customers name");
System.out.println("S) Store program data in to file");
System.out.println("L) Load program data from file");
System.out.println("O) View seats Ordered alphabetically by name");
System.out.println("Q) Exit the application\n");
}
public static void V(String[]seats) {
for (int i = 0; i < seats.length; i++) {
System.out.println(seats[i]);
}
}
public static void A(String[]seats) {
Scanner input = new Scanner(System.in);
System.out.println("What is the name of the customer you want to add? ");
String customerName = input.next();
System.out.println("What seat number do you want this customer to have?");
int seatNumber = input.nextInt();
seats[seatNumber] = customerName;
System.out.println("Thank you, your record was submitted.");
}
public static void E() {
// System.out.println("Empty seats");
//for(int i=0;<seats.length;i++){
// System.out.println("current seat"+ " is ressrved by" + seats[i]);
// }
}
public static void D() {}
public static void F() {}
public static void S() {}
public static void L() {}
public static void O() {
int name;
String temp;
Scanner input = new Scanner(System.in);
System.out.print("Enter all of the pessenger names below; ");
name = input.nextInt();
String names[] = new String[name];
Scanner b1 = new Scanner(System.in);
System.out.println("Enter all the names:");
for (int i = 0; i < name; i++) {
names[i] = b1.nextLine();
}
for (int i = 0; i < name; i++) {
for (int j = i + 1; j < name; j++) {
if (names[i].compareTo(names[j]) > 0) {
temp = names[i];
names[i] = names[j];
names[j] = temp;
}
}
}
System.out.print("Following pessenger names have been Sorted in Order:");
for (int i = 0; i < name - 1; i++) {
System.out.print(names[i] + ",");
}
System.out.print(names[name - 1]);
}
}
public static void main(String[]args) {
String[]seats = new String[SEATING_CAPACITY];
Scanner in = new Scanner(System.in);
char choice;
do {
displayMenu();
System.out.println("Enter a choice or press q to quit the application");
choice = in.next().toUpperCase().charAt(0);
switch (choice) {
case 'A':
A(seats);
break;
case 'V':
V(seats);
break;
case 'E':
E();
break;
case 'D':
D();
break;
case 'F':
F();
break;
case 'S':
S();
break;
case 'L':
L();
break;
case 'O':
O();
break;
default:
System.out.println("You have entered the wrong choice. Please try again!");
}
} while ((choice != 'Q'));
System.out.println("Thank you for using our system.");
}
}

You are probably expecting a String/Text input at this function.
But what you do is the following:
You call the function Scanner.nextInt() which tries to read an Integer/Number value from the console.
What you should do instead of input.nextInt() use input.nextLine() and it shouldn't crash anymore.

Related

How to add for loops to if statements?

In my code below I am not sure what order to put it in to work properly.
I first want it to print out for the user to select an option which it does, then if they select 1 it asks them their name and verifies it with the loop etc.
When I enter a name it starts to just loop the question enter your name and I don't know how to fix it.
Do I need to add more statements to my program, if I do then can I still use if statements for the user to select an option?
import java.util.Scanner;
public class username {
public static void main(String[] args) {
{
int UseLift;
int AuditReport;
int ExitLift;
int a;
UseLift = 1;
AuditReport = 2;
ExitLift = 3;
}
System.out.println("choose an option");
System.out.println("Uselift(1)");
System.out.println("see audit report(2)");
System.out.println("Exit Lift(3)");
Scanner d = new Scanner(System.in);
int a = d.nextInt();
Scanner kb = new Scanner(System.in);
// array containing usernames
String[] name = {"barry", "matty", "olly", "joey"}; // elements in array
if (a == 1) {
System.out.println(" Enter your name ");
}
String name1 = kb.nextLine();
boolean b = true;
int j = 0;// counter will start at 0
outerloop:
while (j < 3) {
System.out.println("Enter your name");
}
for (int i = 0; i < name.length; i++) {
if (name[i].equals(name1)) {
System.out.println("you are verified you may use the lift, calling lift ");
}
break;// to stop loop checking names
}
System.out.println("Username Invalid");
j++;
if (a == 2) {
System.out.println("");
}
if (a == 3) {
System.out.println(" Please Exit Lift ");
}
}
}

here you go:
public static void main(String... args) {
String[] verifiedNames = { "barry", "matty", "olly", "joey" };
System.out.println("choose an option");
System.out.println("Uselift(1)");
System.out.println("see audit report(2)");
System.out.println("Exit Lift(3)");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
switch (choice) {
case 1:
scanner.nextLine(); // get '\n' symbol from previous input
int nameAttemptsLeft = 3;
while (nameAttemptsLeft-- > 0) {
System.out.println(" Enter your name ");
String name = scanner.nextLine();
if (Arrays.asList(verifiedNames).contains(name)) {
System.out.println("dear " + name + " you are verified " +
"you may use the lift, calling lift ");
break; // break out of loop
}
}
if (nameAttemptsLeft < 0) {
System.out.println("Username Invalid");
}
break;
case 2:
System.out.println("option 2");
break;
case 3:
System.out.println(" Please Exit Lift ");
break;
}
scanner.close();
}

Your while loop below:
while (j < 3) {
System.out.println("Enter your name");
}
will loop forever since j is not incrementing (j++). I believe you've mis-matched your curly braces at some point.

Trying to sort objects in an arraylist by a property but the objects don't always sort properly

I have four classes but they're just templates so I'll only post my main class (I have overridden toString for each). The sort method is at the bottom. Everything else is fine (more or less) with my code, but when I create the objects in the array and then go to sort them (by a string value called uid) sometimes one or two of them will be out of order. How can I fix this?
Here's the code:
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.InputMismatchException;
import java.util.Scanner;
enum ClassStanding{FRESHMAN,SOPHOMORE,JUNIOR,SENIOR,UNKNOWN,MASTERS_STUDIES,PHD_STUDIES};
enum Major{CS,CEG,EE,ISE,BME,ME,MET,UNKNOWN};
enum StudentType{UNDERGRADUATE,GRADUATE,UNDECLARED};
public class Main {
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
Scanner stdin = new Scanner(System.in);
ArrayList<Student> studentList = new ArrayList<>();
int counter;
boolean continueInput;
int contCounter;
do {
do {
System.out.print("Please enter what you want to do-ADD, REMOVE, SORT, LIST, or SAVE: ");
switch (stdin.next().toLowerCase()) {
case "add":
add(stdin, studentList);
counter = 0;
break;
case "remove":
remove(studentList, stdin);
counter = 0;
break;
case "list":
list(studentList);
counter = 0;
break;
case "save":
String fileName = getFileName(stdin);
save(fileName, studentList);
counter = 0;
break;
case "sort":
counter = 0;
sort(studentList);
break;
default:
System.out.println("Improper input, please enter only ADD, REMOVE, LIST, or SAVE.");
counter = 1;
}
} while (counter == 1);
do {
System.out.print("\nDo you want to continue? Yes or no: ");
switch (stdin.next().toLowerCase()) {
case "yes":
contCounter = 0;
continueInput = true;
break;
case "no":
contCounter = 0;
continueInput = false;
break;
default:
contCounter = 1;
continueInput = false;
System.out.print("\nPlease only enter 'yes' or 'no'.");
}
} while (contCounter == 1);
} while (continueInput);
} // end main method
public static void add(Scanner stdin, ArrayList<Student> studentList) {
String firstName;
String lastName;
String uid;
StudentType studentType;
ClassStanding studentClassStanding;
Major major;
double overallGPA;
double majorGPA;
String majorProfessor;
boolean thesisOption;
System.out.print("Please enter the student's first name: ");
String tempName = stdin.next();
firstName = checkName(tempName);
System.out.print("Please enter the student's last name: ");
tempName = stdin.next();
lastName = checkName(tempName);
System.out.println("Please enter the student's UID in the format 'U####' or 'U#####': ");
String tempUID = stdin.next();
uid = checkUID(tempUID).toUpperCase();
int count;
do {
System.out.print("Please enter the student's status as UNDECLARED, UNDERGRADUATE, or GRADUATE: ");
switch (stdin.next().toUpperCase()) {
case "UNDECLARED":
studentType = StudentType.UNDECLARED;
studentClassStanding = setStudentClassStanding(studentType);
count = 0;
Student student = new Student(firstName, lastName,
uid, studentType, studentClassStanding);
studentList.add(student);
break;
case "UNDERGRADUATE":
studentType = StudentType.UNDERGRADUATE;
major = setMajor();
studentClassStanding = setStudentClassStanding(studentType);
System.out.println("Enter the student's overall GPA below.");
overallGPA = setGPA();
System.out.println("Enter the student's major GPA below.");
majorGPA = setGPA();
count = 0;
UnderGraduate underGraduate = new UnderGraduate(firstName, lastName, uid, studentType,
studentClassStanding, major, overallGPA, majorGPA);
studentList.add(underGraduate);
break;
case "GRADUATE":
studentType = StudentType.GRADUATE;
studentClassStanding = setStudentClassStanding(studentType);
majorProfessor = setMajorProfessor();
thesisOption = setThesisOption();
count = 0;
Graduate graduate = new Graduate(firstName, lastName, uid, studentType,
studentClassStanding, majorProfessor, thesisOption);
studentList.add(graduate);
break;
default:
System.out.println("Please enter either Undeclared, Undergraduate, or Graduate only.");
count = 1;
}
} while (count == 1);
} // end add method
public static String checkName(String tempName) {
int a = 1;
String name1;
Scanner scanner = new Scanner(System.in);
do {
name1 = tempName; // hold the value of firstName in name1
for (int i = 0; i < tempName.length(); i++) { // loop to check input consists of letters (is a name)
if (!Character.isLetter(tempName.charAt(i))) { // if non-letters detected, ensure this was intentional
System.out.println("Please ensure you've entered the correct name. Re-enter the name or enter 'continue' to proceed: ");
tempName = scanner.nextLine();
if (tempName.equalsIgnoreCase("continue")) { // if user enters "continue", use original input
a = 0;
tempName = name1; // pass name1 value to firstName
break;
} else {
a = 1; // continue prompting for firstName
}
} else { // accept input
a = 0;
}
}
} while (a == 1); // loop to ensure proper input
return tempName;
} // end checkName method
public static String checkUID(String tempUID) {
Scanner scan = new Scanner(System.in);
int a;
do {
if (tempUID.charAt(0) == 'U' || tempUID.charAt(0) == 'u') {
if (tempUID.length() == 6 || tempUID.length() == 5) {
a = 0;
} else {
a = 1;
System.out.print("Please ensure input is in the form of U#### or U#####. Please re-enter the UID: ");
tempUID = scan.next();
}
} else {
a = 1;
System.out.print("Please ensure input is in the form of U#### or U#####. Please re-enter the UID: ");
tempUID = scan.next();
}
} while (a == 1);
return tempUID;
} // end checkUID method
public static ClassStanding setStudentClassStanding(StudentType studentType) {
Scanner scan = new Scanner(System.in);
int count;
ClassStanding studentTempClassStanding = null;
do {
if (studentType == StudentType.UNDECLARED || studentType == StudentType.UNDERGRADUATE) {
System.out.print("Please enter the student's class standing as either Freshman, Sophomore, Junior, Senior, or Unknown: ");
switch (scan.next().toUpperCase()) {
case "FRESHMAN":
studentTempClassStanding = ClassStanding.FRESHMAN;
count = 0;
break;
case "SOPHOMORE":
studentTempClassStanding = ClassStanding.SOPHOMORE;
count = 0;
break;
case "JUNIOR":
studentTempClassStanding = ClassStanding.JUNIOR;
count = 0;
break;
case "SENIOR":
studentTempClassStanding = ClassStanding.SENIOR;
count = 0;
break;
case "UNKNOWN":
studentTempClassStanding = ClassStanding.UNKNOWN;
count = 0;
break;
default:
System.out.println("Please enter only Freshman, Sophomore, Junior, Senior, or Unknown.");
count = 1;
}
} else {
System.out.print("Please enter the student's class standing as either 'Masters' for Masters Studies or 'PhD' for PhD Studies: ");
switch (scan.next().toUpperCase()) {
case "MASTERS": studentTempClassStanding = ClassStanding.MASTERS_STUDIES; count = 0; break;
case "PHD": studentTempClassStanding = ClassStanding.PHD_STUDIES; count = 0; break;
default: System.out.println("Please enter only 'Masters' or 'PhD'.");
count = 1;
}
}
} while (count == 1);
return studentTempClassStanding;
} // end setStudentClassStanding method
public static Major setMajor() {
Major tempMaj = null;
Scanner s = new Scanner(System.in);
int c;
do {
System.out.print("Please enter the student's major as either CS, CEG, EE, ISE, BME, ME, MET, or Unknown: ");
switch (s.next().toUpperCase()) {
case "CS":
tempMaj = Major.CS;
c = 0;
break;
case "CEG":
tempMaj = Major.CEG;
c = 0;
break;
case "EE":
tempMaj = Major.EE;
c = 0;
break;
case "ISE":
tempMaj = Major.ISE;
c = 0;
break;
case "BME":
tempMaj = Major.BME;
c = 0;
break;
case "ME":
tempMaj = Major.ME;
c = 0;
break;
case "MET":
tempMaj = Major.MET;
c = 0;
break;
case "UNKOWN":
tempMaj = Major.UNKNOWN;
c = 0;
break;
default:
System.out.println("Please enter only the specified values. ");
c = 1;
}
} while (c == 1);
return tempMaj;
} // end setMajor method
public static double setGPA() {
Scanner s = new Scanner(System.in);
double gpa;
int a;
do {
try {
System.out.print("Please enter the student's GPA: ");
gpa = s.nextDouble();// read in the gpa
if (gpa < 0.0 || gpa > 4.0) { // ensure the gpa is in the correct range
System.out.println("Invalid input, please enter a positive value between 0.0 and 4.0.");
a = 1;
} else {
a = 0;
}
} catch (InputMismatchException ex) { //catch any exceptions, prompt for correct input
a = 1;
gpa = 0.0;
System.out.println("Sorry, please enter a double value.");
s.nextLine(); // skip the last input
}
} while (a == 1 || gpa < 0.0 || gpa > 4.0); //loop while gpa is negative or incorrect input is received
return gpa;
} // end setGPA method
private static String setMajorProfessor() {
Scanner s = new Scanner(System.in);
String prof;
System.out.print("Please enter the name of the major professor: ");
String tempName = s.nextLine();
prof = checkName(tempName);
return prof;
} // end setMajorProfessor method
private static boolean setThesisOption() {
Scanner s = new Scanner(System.in);
boolean thesis = false;
int a;
do {
System.out.print("Please enter 'yes' if a thesis will be written, otherwise enter 'no': ");
switch (s.next().toUpperCase()) {
case "YES": thesis = true; a = 0; break;
case "NO": thesis = false; a = 0; break;
default: System.out.println("Please enter only 'yes' or 'no'."); a = 1;
}
} while (a == 1);
return thesis;
} // end setThesisOption method
private static void list(ArrayList<Student> studentList) {
for (int i = 0; i < studentList.size(); i++) {
System.out.println(studentList.get(i).toString());
}
} // end list method
public static String getFileName(Scanner stdin) {
System.out.print("Please enter the file name: "); // Prompt for input
String fileString = stdin.next();
return fileString; // Pass the fileString var to the main method
}//end of getFileName method
private static void save(String fileName, ArrayList<Student> studentList) {
int a; // create a counter
Scanner stdin = new Scanner(System.in);
do {
try {
PrintWriter writer = new PrintWriter(fileName); // Create a printwriter
for (int i = 0; i < studentList.size(); i++) {
writer.print(studentList.get(i).toString() + "\n"); //Print the arraylist to file
}
writer.close(); //Close the printwriter and save the file
a = 0;
} catch (FileNotFoundException ex) { // Catch any exceptions
System.out.println("The file could not be found, please re-enter the file name: "); // get new file name if an exception is thrown
fileName = stdin.nextLine();
a = 1;
}
} while (a == 1); // loop while exceptions are thrown
System.out.println("All information has been saved at " + fileName); // output that the arraylist has been saved in the specified file
// Make the following its own method
System.out.print("Would you like to read the contents of the file? Yes or no: ");
int b;
do {
switch (stdin.next().toLowerCase()) {
case "yes": readFromFile(fileName); b = 0; break;
case "no": b = 0; break;
default: System.out.println("Please enter only yes or no."); b = 1;
}
} while (b == 1);
} // end save method
private static void remove(ArrayList<Student> studentList, Scanner stdin) {
System.out.print("Please enter the UID of the student to be removed: ");
String tempUID = stdin.next();
String uidRemove = checkUID(tempUID);
for (int i = 0; i < studentList.size(); i++) {
if ((studentList.get(i).getUid()).equalsIgnoreCase(uidRemove)) {
studentList.remove(i);
}
}
System.out.println("The student with UID " + uidRemove + " has been removed.");
} // end remove method
private static void sort(ArrayList<Student> studentList) {
String uidLessU1;
String uidLessU2;
for (int i = 0; i < studentList.size(); i++) {
uidLessU1 = (studentList.get(i).getUid()).substring(1, studentList.get(i).getUid().length());
for (int j = 0; j < studentList.size(); j++) {
uidLessU2 = (studentList.get(j).getUid()).substring(1, studentList.get(j).getUid().length());
if (Integer.parseInt(uidLessU1) < Integer.parseInt(uidLessU2)) {
Student hold = studentList.get(i);
studentList.set(i, studentList.get(j));
studentList.set(j, hold);
}
}
}
} // end sort method
private static void readFromFile(String fileName) {
System.out.println("The contents of " + fileName + " as read from NotePad: ");
try {
Scanner fileReader = new Scanner(new File(fileName)); //Create a scanner
while (fileReader.hasNextLine()) { //Loop to read the file
String fromFile = fileReader.nextLine();
System.out.println(fromFile); //Output the file contents
}
} catch (FileNotFoundException ex) { //Catch any exceptions
System.out.println("Exception caught");
}
} // end readFromFile method
} // end main class
A sample of the problem would be (at this point I've already entered all the values instantiating the objects):
Do you want to continue? Yes or no: yes
Please enter what you want to do-ADD, REMOVE, SORT, LIST, or SAVE: list
Student s w whose UID is U3333 is a
UNDECLARED student doing JUNIOR work.
Student p o whose UID is U1111 is a
UNDECLARED student doing JUNIOR work.
Student p u whose UID is U44444 is a
UNDECLARED student doing JUNIOR work.
Student w e whose UID is U4444 is a
UNDECLARED student doing JUNIOR work.
Student s r whose UID is U2222 is a
UNDECLARED student doing JUNIOR work.
Student s u whose UID is U7777 is a
UNDECLARED student doing JUNIOR work.
Student po iu whose UID is U77777 is a
UNDECLARED student doing JUNIOR work.
Do you want to continue? Yes or no: yes
Please enter what you want to do-ADD, REMOVE, SORT, LIST, or SAVE: sort //calls the sort method
Do you want to continue? Yes or no: yes
Please enter what you want to do-ADD, REMOVE, SORT, LIST, or SAVE: list // calls the list method and prints out the arraylist
Student p o whose UID is U1111 is a
UNDECLARED student doing JUNIOR work.
Student s r whose UID is U2222 is a
UNDECLARED student doing JUNIOR work.
Student s w whose UID is U3333 is a
UNDECLARED student doing JUNIOR work.
Student s u whose UID is U7777 is a //why is this out of place?
UNDECLARED student doing JUNIOR work.
Student w e whose UID is U4444 is a
UNDECLARED student doing JUNIOR work.
Student p u whose UID is U44444 is a
UNDECLARED student doing JUNIOR work.
Student po iu whose UID is U77777 is a
UNDECLARED student doing JUNIOR work.

Just make Student implement Comparable and then you can do
Collections.sort(studentList);

ClassCastException in BookingApp

I'm getting a ClassCastException at:
RVBooking rvbooking = (RVBooking) bookingList.get(iweight);
I want to store the user's weightvehicle input and invoke the recordWeight() method. Sorry if i am not explaining this clearly. Thanks in advance.
Stack Trace
FerryBookingSystem [Java Application]
bookingSystem.FerryBookingSystem at localhost:51019
Thread [main] (Suspended (exception ClassCastException))
FerryBookingSystem.recordVehicleWeight() line: 144
FerryBookingSystem.main(String[]) line: 191
C:\Program Files\Java\jre7\bin\javaw.exe (16/05/2013 12:42:10 AM)
BookingException
class BookingException extends Exception{
String message;
String IDs;
public BookingException(String message){
this.message = message;
}
public BookingException(String message, String IDs){
this.message = message;
this.IDs = IDs;
}
public String getIDs(){
return IDs;
}
public String getMessage(){
return message;
}
}
FerryBookingSystem Class
public class FerryBookingSystem {
private static ArrayList<VehicleBooking> bookingList = new ArrayList<VehicleBooking>();
private static ArrayList<RVBooking> rvbookingList = new ArrayList<RVBooking>();
private static Scanner userInput = new Scanner (System.in);
public static int bookingIDExists(String IDs){
if (bookingList.size() == -1){
return -1;
}
for (int i = 0; i < bookingList.size(); i++){
if(bookingList.get(i).getbookingID().equals(IDs)){
return i;
}
}
return -1;
}
public static int rvbookingIDExists(String IDs){
if (rvbookingList.size() == -1){
return -1;
}
for(int i = 0; i < rvbookingList.size(); i++){
if(rvbookingList.get(i).getbookingID().equals(IDs)){
return i;
}
}
return -1;
}
public static boolean recordVehicleWeight(){
String booking_ID;
double weight = 0;
int iweight = 0;
System.out.print("Please enter the booking ID: ");
booking_ID = userInput.nextLine();
if(bookingIDExists(booking_ID) != -1){
if(rvbookingIDExists(booking_ID) != 1){
RVBooking rvbooking = (RVBooking) bookingList.get(iweight);
System.out.print("Please enter the weight of the vehicle: ");
weight = userInput.nextDouble();
iweight = (int)weight;
rvbooking.recordWeight(iweight);
return true;
}
else{
System.out.println("Error - cannot record weight for vehicle booking!");
return false;
}
}
else{
System.out.println("The booking ID does not exist, Please try again.");
return false;
}
}
public static void main (String [] args) throws IOException{
char user;
do{
System.out.println("**** Ferry Ticketing System ****");
System.out.println(" A - Add Vehicle Booking");
System.out.println(" B - Add Recreational Vehicle Booking");
System.out.println(" C - Display Booking Summary");
System.out.println(" D - Update Insurance Status");
System.out.println(" E - Record Recreational Vehicle Weight");
System.out.println(" F - Compile Vehicle Manifest");
System.out.println(" X - Exit");
System.out.print("Enter your selection: ");
String choice = userInput.nextLine().toUpperCase();
user = choice.length() > 0 ? choice.charAt(0) : '\n';
if (choice.trim().toString().length()!=0){
switch (user){
case 'A':
addVehicleBooking();
break;
case 'B':
addRecreationalVehicleBooking();
break;
case 'C':
displayBookingSummary();
break;
case 'D':
updateInsuranceStatus();
break;
case 'E':
recordVehicleWeight();
break;
case 'F':
break;
case 'X':
break;
default:
break;
}
}
}while(user!='X');
}
}

You are trying to cast RVBooking type to object from VehicleBooking list

Looks like your bookingList is meant to store objects of type VehicleBooking, and you are trying to cast that object to RVBooking while getting from the list
private static ArrayList<VehicleBooking> bookingList = new ArrayList<VehicleBooking>();
unless RVBooking is super class of VehicleBooking, VehicleBooking cannot be cast to RVBooking

How to connect Sequencial Search to an array and Main Menu

I am trying to connect the sequential search function to the menu so that it accepts user input and search the tp arrays in apartA() and apartB(). And also how can we connect the report function to the values in Functions apartA() and apartB().
package jachi;
import java.util.Scanner;
public class Jachi {
public static void main(String[] args) {
menu();
}
public static void menu(){
int j,k,choice;
System.out.println("Menu");
System.out.println("1. Register");
System.out.println("2. Update");
System.out.println("3. Report");
System.out.println("4. Search");
Scanner scan=new Scanner(System.in);
choice=scan.nextInt();
switch(choice) {
case 1:
System.out.println("Select Apartment type");
System.out.println("1. Apartment A");
System.out.println("2. Apartment B.");
choice=scan.nextInt();
if (choice==1)
{
apartA();
}
else if (choice==2)
{
apartB();
}
break;
case 2:
System.out.println("Update the student information");
break;
case 3:
System.out.println("Rooms Available");
report();
break;
case 4:
System.out.print("Search for student. Please enter the TP number:");
break;
default:
System.out.println("Incorrect input");
}
}
public static int apartA()
{
final int a = 9;
//Normal Rooms Arrays
int[] tp;
tp = new int[a];
String[] stname;
stname = new String[a];
String[] mob;
mob = new String[a];
int ttt = get.nextInt();
int test = sequencialSearch(ttt);
Scanner get = new Scanner(System.in);
//Data Entry
for (int index = 0; index < a; index++)
{
System.out.println("Student Information");
System.out.println("Enter the student TP NUMBER:");
tp[index] = get.nextInt();
System.out.println("Enter the STUDENT NAME:");
stname[index] = get.nextLine();
System.out.println("Enter the MOBILE NUMBER:");
mob[index] = get.nextLine();
rent();
}
System.out.println("Rooms Full");
/**Report Data, Test for Data presence
*for(a=0;a<=2;a++)
*{
*System.out.println("TP NUMBER: "+tp[a]+"\t NAME: "+stname[a]+"\t MOBILE: "+mob[a]);
*}*/
return a;
}
public static void apartB(){
System.out.println("Select Room Type");
System.out.println("\t1. Normal Room");
System.out.println("\t2. Master Room");
int choice;
final int j = 6;
final int k = 3;
Scanner get = new Scanner(System.in);
choice = get.nextInt();
Scanner get1 = new Scanner(System.in);
if (choice==1)
{
System.out.println("1. Normal Bedroom");
// Normal Bedroom Arrays
String[] tp;
tp = new String[j];
String[] stname;
stname = new String[j];
String[] mob;
mob = new String[j];
//Data Entry
for (int index = 0; index < j; index++)
{
System.out.println("Student Information");
System.out.println("Enter the student TP NUMBER:");
tp[index] = get1.nextLine();
System.out.println("Enter the STUDENT NAME:");
stname[index] = get1.nextLine();
System.out.println("Enter the MOBILE NUMBER:");
mob[index] = get1.nextLine();
rent();
}
if(j<=5)
{
menu();
}
else
{
System.out.println("All Houses Full");
}
}
else if (choice==2)
{
System.out.println("Master bedroon");
//Master Bedroom Arrays
String[] mastertp;
mastertp = new String[k];
String[] mastername;
mastername = new String[k];
String[] mastermob;
mastermob = new String[k];
//Data Entry
for (int index = 0; index < k; index++)
{
System.out.println("Student Information");
System.out.println("Enter the student TP NUMBER:");
mastertp[index] = get1.nextLine();
System.out.println("Enter the STUDENT NAME:");
mastername[index] = get1.nextLine();
System.out.println("Enter the MOBILE NUMBER:");
mastermob[index] = get1.nextLine();
int x,y,z,pay;
x=100;
pay=300;
y=3*pay;
z=x+y;
System.out.println("Charges to be Paid");
System.out.println("Charges Amount");
System.out.println("Utilities charge: rm100");
System.out.println("Three month rental: rm"+y);
System.out.println("Total: rm"+z);
menu();
}
System.out.println("Full House Man");
}
}
public static void rent(){
int x,y,z,pay;
x=100;
pay=300;
y=3*pay;
z=x+y;
System.out.println("Charges to be Paid");
System.out.println("Charges Amount");
System.out.println("Utilities charge: rm100");
System.out.println("Three month rental: rm"+y);
System.out.println("Total: rm"+z);
menu();
}
public static void report(){
int x,y,z;
x=0;
y=x+1;
z=6-y;
System.out.println("Rooms occupied; "+y);
System.out.println("Rooms available; "+z);
menu();
}
public static int sequencialSearch(int Tnumbr){
int index,
element;
boolean found;
index = 0;
element = 0;
found = false;
while(!found && index == Tnumbr){
/* if(array[index] == 9{
* found = true;
* element = index;
* }
* index++;
*/
}
return element;
}
}

Ok that is a lot of code, lets try breaking it into simpler classes.
first would be Apartment. Lets have a class for apartment and put all the utility methods like report() and search() into it.
The apartment class can be something like:
import java.util.HashMap;
import java.util.List;
import java.util.Scanner;
class Apartment{
/** Integer: roomid, String StrudentId **/
HashMap<Integer, String> rooms = new HashMap<Integer, String>();
public Apartment(){
}
public Integer sequentialSearch(String tpNumber){
/** Returns null if student is absent **/
for(Integer roomId : rooms.keySet())
{
if(tpNumber.equals(rooms.get(roomId)))
return roomId;
}
return null;
}
public void report(){
System.out.println("ROOM_NUM\tSTUDENT_ID");
for(Integer roomId : rooms.keySet())
{
System.out.println(roomId +"\t" + rooms.get(roomId));
}
}
}
Now in your Main class Jachi you can create and use the apartments like:
Apartment apartA = new Apartment();
apartA.sequentialSearch("SOME_STUDENTID_HERE");
apartA.report();
Apartment apartB = new Apartment();
apartB.sequentialSearch("SOME_STUDENTID_HERE");
apartB.report();
You can also create Arrays of apartments now. Rest is left for you to explore.

Show a java console menu again after switch finishes

I am trying to write a java console menu but i can't render it in the console. Here is the code i wrote so far.
package com.registrar;
import java.util.*;
class GUIMenu {
private Course[] courses = new Course[100];
private Person[] persons = new Person[1000];
public void display_menu() {
System.out.println("****************MENU*****************");
System.out.println("[1] Add Course\n[2] Add Student to Course \n[3] Verify Registration \n[4] Remove Student \n[5] Add Persons");
System.out.println("**************************************");
System.out.println("Selection: ");
}
public GUIMenu(){
Person p = null;
Scanner in = new Scanner (System.in);
int input = in.nextInt();
switch (input){
case 1:
Scanner sc = new Scanner(System.in);
System.out.println("Enter Course Name: ");
String name = sc.nextLine();
System.out.println("Enter Course ID:");
Integer cID = sc.nextInt();
System.out.println("Enter Instructor ID:");
Integer pn = sc.nextInt();
for(int i = 0; i < persons.length; i ++){
System.out.println(persons[i]);
}
for(int i = 0; i<persons.length; i++){
if(persons[i] !=null){
if(persons[i].getId().intValue() == pn){
System.out.println("Record Found");
p = persons[i];
}
else
System.out.println("Record Not Found");
}
}
Course c = new Course(name, cID);
if(p!=null){
Instructor ins = new Instructor(p);
c.setInstructor(ins);
}
System.out.println(c + " has been created");
for(int i = 0; i < courses.length; i ++){
if(courses[i] == null){
courses[i] = c;
break;
}
}
new GUIMenu();
case 2:
for(int i = 0; i < courses.length; i ++){
if(courses[i] != null)
System.out.println(courses[i]);
}
break;
case 3:
System.out.println ( "You picked option 3" );
break;
case 4:
System.out.println ( "You picked option 4" );
break;
case 5:
Scanner pers = new Scanner(System.in);
System.out.println("Enter Person Name: ");
String pname = pers.nextLine();
System.out.println("Enter Person ID:");
Integer oiID = pers.nextInt();
Person per = new Person(pname, oiID);
for(int i = 0; i < persons.length; i ++){
if(persons[i] == null){
persons[i] = per;
break;
}
}
display_menu();
default:
System.err.println("Unrecognized option");
}
}
public static void main ( String[] args ) {
GUIMenu a = new GUIMenu();
a.display_menu();
}
}
I am trying that after a selection on the menu the code returns the menu again after completing the code associated with that particular selection. What i am doing wrong? I dont see the menu at all displaying.

What i am doing wrong?
Look at the code: This is where it starts:
public static void main ( String[] args ) {
GUIMenu a = new GUIMenu(); // This is executed first...
a.display_menu();
}
let's have a look at it
public GUIMenu(){
Person p = null;
Scanner in = new Scanner (System.in);
int input = in.nextInt(); // this is where it's waiting for your input.
...
Looking at the flow of your code, it is pretty clear why the menu is not shown.
EDIT:
You are looking for something like this:
public void runApplication() {
// init Scanner
boolean nextRound = true;
while(nextRound) {
displayMenu();
int input = sc.nextInt();
switch(input) {
case 1: // do stuff
break;
case 2: // this is the exit command
nextRound = false;
break;
// more cases
default:
// undefined input
}
}
}
So you use your constructor only for constructor relevant code and later call the runApplication() method.

We Keep Coding

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Why does my program crash when i excute method "O"? - java

You are probably expecting a String/Text input at this function. But what you do is the following: You call the function Scanner.nextInt() which tries to read an Integer/Number value from the console. What you should do instead of input.nextInt() use input.nextLine() and it shouldn't crash anymore.

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Show a java console menu again after switch finishes

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