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How to fix inputting the user's info twice?

The program ask for a month and it could be a string or int. In the isDigitsOrSpecial method, it works and it has the same format in my method isString. The difference is that when I want to enter the month in a string way (ex.january), it will ask me twice. So, I don't know what to do. I tried a lot of ways but it doesn't work. Do you have any suggestions?
Here's my full code. You can try to run it, and see the problem where you have to input twice the name of the month in a string way.
I would really appreciate any of your suggestions.
package Electronic_payment_process;
import java.util.InputMismatchException;
import java.util.Scanner;
public class practice {
static String s;
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
float current = 0, recent = 0, difference, multiply;
String month, recents, currents = null;
System.out.println("The month could be a number or a name.");
System.out.println("Example: (01-12) or (JAN – dec)");
// for the validation of due month user’s input
do {
System.out.print("\nEnter a month: ");
month = scan.next();
if (isDigitsOrSpecial(month)) {
System.out.print("proceed");
break;
} else if (isString(month)) {
System.out.print("proceed");
break;
}
} while (true);
// for the validation of current meter reading
do {
System.out.print("\nEnter current reading: ");
try {
current = scan.nextFloat();
System.out.println("proceed");
currents = String.format("%.2f", current);
if (current <= 0) {
System.out.println("Invalid input");
}
} catch (InputMismatchException a) {
System.out.println("Must enter a number");
scan.next();
}
} while (current <= 0);
// for the validation of recent meter reading
do {
System.out.print("Enter recent reading: ");
try {
recent = scan.nextFloat();
if (recent < current) {
System.out.println("proceed");
recents = String.format("%.2f", recent);
break;
} else {
System.out.println("recent must be less than current");
}
} catch (InputMismatchException a) {
System.out.println("Must enter a number");
scan.next();
}
} while (true);
difference = current - recent;
multiply = difference * 50;
System.out.println("====================================================================================");
System.out.println("MONTH " + " RECENT " + "CURRENT " + "TOTAL USAGE " + "Price per unit " + "TOTAL AMOUNT ");
System.out.println((s + (" ") + recents + (" kW") + (" ") + currents + (" kW") + (" ") + difference + (" ") + ("50php") + (" ") + multiply));
}
public static boolean isDigitsOrSpecial(String month) {
Scanner scan = new Scanner(System.in);
if (month != null) {
for (char ch : month.toCharArray()) {
if (Character.isLetter(ch)) {
return false;
}
}
}
int we = Integer.parseInt(month);
s = Integer.toString(we);
if (null == month) {
s = scan.nextLine();
} else switch (we) {
case 01:
s = "January";
break;
case 02:
s = "February";
break;
case 03:
s = "March";
break;
case 04:
s = "April";
break;
case 05:
s = "May";
break;
case 06:
s = "June";
break;
case 07:
s = "July";
break;
case 8:
s = "August";
break;
case 9:
s = "September";
break;
case 10:
s = "October";
break;
case 11:
s = "November";
break;
case 12:
s = "December";
break;
default:
System.out.println("You have entered an invalid number of month");
}
return true;
}
public static boolean isString(String month) {
Scanner scan = new Scanner(System.in);
if (null != month) {
char[] chars = month.toCharArray();
s = scan.nextLine();
for (char c : chars) {
if (!Character.isLetter(c)) {
return false;
}
}
}
if (!(month.length() >= 3)) {
System.out.println("Name of month must be at least 3 letters.Please try again");
return false;
} else if (month.startsWith("jan") || month.startsWith("JAN") || month.startsWith("Jan")) {
s = "January";
}
return true;
}
}

I see we have added additional scanner statements inside isDigit or isString methods. I have removed them and it looks good to me.
public static boolean isDigitsOrSpecial(String month) {
if (month != null) {
for (char ch : month.toCharArray()) {
if (Character.isLetter(ch)) {
return false;
}
}
}
int we = Integer.parseInt(month);
switch (we) {
case 01:
s = "January";
break;
case 02:
s = "February";
break;
case 03:
s = "March";
break;
case 04:
s = "April";
break;
case 05:
s = "May";
break;
case 06:
s = "June";
break;
case 07:
s = "July";
break;
case 8:
s = "August";
break;
case 9:
s = "September";
break;
case 10:
s = "October";
break;
case 11:
s = "November";
break;
case 12:
s = "December";
break;
default:
System.out.println("You have entered an invalid number of month");
return false;
}
return true;
}
public static boolean isString(String month)
{
if (null != month) {
char[] chars = month.toCharArray();
for (char c : chars) {
if (!Character.isLetter(c)) {
return false;
}
}
}
if (!(month.length() >= 3)) {
System.out.println("Name of month must be at least 3 letters.Please try again");
return false;
}
return true;
}

How to create in Java solution just with "switch and if" such an input "January " or "janUARY" [duplicate]

This question already has answers here:
Case insensitive matching in Java switch-case statement
(5 answers)
Closed 4 years ago.
How to create in Java solution just with "switch and if" such an input "January", "january", JANUARY", janUARY" and any other combination of case is treated as "January" and in all cases prints out 1. I did program, but it is working just with the same input words, maybe exist a trick to resolve that.
import java.util.Scanner;
public class nameMonth
{
public static void main(String[] args)
{
String month;
int nrMonth;
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter a month");
month = keyboard.nextLine();
switch (month)
{
case "January":
System.out.println("Your month is January");
nrMonth = 1;
break;
case "February":
System.out.println("Your month is February");
nrMonth = 2;
break;
case "March":
System.out.println("Your month is March");
nrMonth = 3;
break;
case "April":
System.out.println("Your month is April");
nrMonth = 4;
break;
case "May":
System.out.println("Your month is May");
nrMonth = 5;
break;
case "June":
System.out.println("Your month is June");
nrMonth = 6;
break;
case "July":
System.out.println("Your month is July");
nrMonth = 7;
break;
case "August":
System.out.println("Your month is August");
nrMonth = 8;
break;
case "September":
System.out.println("Your month is September");
nrMonth = 9;
break;
case "October":
System.out.println("Your month is October");
nrMonth = 10;
break;
case "November":
System.out.println("Your month is November");
nrMonth = 11;
break;
case "December":
System.out.println("Your month is December");
nrMonth = 12;
break;
default:
System.err.println("Your month is wrong");
break;
}
}
}

Use this:
switch (month.toUpperCase()) {
Then, the cases should be in uppercase, such as:
case "JANUARY":
System.out.println("Your month is January");
nrMonth = 1;
break;

Unless you're required to use a switch for some reason, you could do something like this:
private int getMonthInYear(string month) {
string[] monthsInYear = {"JANUARY", "FEBRUARY", "MARCH", "APRIL", ..., "DECEMBER" };
for (int i = 0; i < monthsInYear.length; i++) {
if (monthsInYear[i].equalsIgnoreCase(month))
return i+1; // Compensate for 0 indexing
}
return -1; // In case it's not found
}
Then just call this method in your main. In general, sounds like you're looking for the equalsIgnoreCase(string s) string function or something similar.

You can use this
String withCase = month.substring(0, 1).toUpperCase()+month.substring(1).toLowerCase();
switch (withCase) {
case "January":
System.out.println("Your month is January");
nrMonth = 1;
break;

You can do this
import java.util.Scanner;
public class nameMonth {
public static void main(String[] args) {
String month;
int nrMonth;
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter a month");
month = keyboard.nextLine();
if("January".equalsIgnoreCase(month)) {
System.out.println("Your month is January");
nrMonth = 1;
}
else if("February".equalsIgnoreCase(month)) {
System.out.println("Your month is February");
nrMonth = 2;
}
else if("March".equalsIgnoreCase(month)) {
System.out.println("Your month is March");
nrMonth = 3;
}
else if("April".equalsIgnoreCase(month)) {
System.out.println("Your month is April");
nrMonth = 4;
}
else if("May".equalsIgnoreCase(month)) {
System.out.println("Your month is May");
nrMonth = 5;
}
else if("June".equalsIgnoreCase(month)) {
System.out.println("Your month is June");
nrMonth = 6;
}
else if("July".equalsIgnoreCase(month)) {
System.out.println("Your month is July");
nrMonth = 7;
}
else if("August".equalsIgnoreCase(month)) {
System.out.println("Your month is August");
nrMonth = 8;
}
else if("September".equalsIgnoreCase(month)) {
System.out.println("Your month is September");
nrMonth = 9;
}
else if("October".equalsIgnoreCase(month)) {
System.out.println("Your month is October");
nrMonth = 10;
}
else if("November".equalsIgnoreCase(month)) {
System.out.println("Your month is November");
nrMonth = 11;
}
else if("December".equalsIgnoreCase(month)) {
System.out.println("Your month is December");
nrMonth = 12;
}
else {
System.err.println("Your month is wrong");
}
}
}

You can simply use this line of code at the beginning (right below month = keyboard.nextLine();) and you will not have to change anything in your code.
month = month.substring(0,1).toUpperCase().concat(month.substring(1).toLowerCase());

You can do this.
String month;
int nrMonth;
month.toUpperCase(); // Convert to Upper Case.
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter a month");
month = keyboard.nextLine();
switch (month)
{
case "JANUARY": //Change all to caps.
System.out.println("Your month is January");
nrMonth = 1;
break;
///ETC...

How to use switch-statement correctly?

I need to write a Java program (class NextDay) that calculates and prints the date of the next day by entering the day, month, and year.
Sample call and output:
Actual Date 12.12.2004
The next day is the 13.12.2004.
The input should also be checked for correctness! If an erroneous date constellation (e.g., 32 12 2007) has been entered, the exception InvalidDateArgumentsException is to be thrown. Define this class in a suitable form as a subclass of the class java.lang.Exception.
I started to creating it but the problem is; i cant tell that < or > in switch statements.What should i do? Here are my classes:
public class Date {
private int day;
private int month;
private int year;
public Date(int day, int month, int year) {
this.day = day;
this.month = month;
this.year = year;
}
public Date getNextDay() throws Exception {
if (isLeapYear() == true) {
switch (month) {
case 1:
day = 31;
break;
case 2:
day = 29;
break;
case 3:
day = 31;
break;
case 4:
day = 30;
break;
case 5:
day = 31;
break;
case 6:
day = 30;
break;
case 7:
day = 31;
break;
case 8:
day = 31;
break;
case 9:
day = 30;
break;
case 10:
day = 31;
break;
case 11:
day = 30;
break;
case 12:
day = 31;
break;
}
}
return new Date(day + 1, month, year);
}
public int getDay() {
return day;
}
public int getMonth() {
return month;
}
public int getYear() {
return year;
}
public boolean isLeapYear() {
if (year % 4 == 0 && year % 100 != 0 && year % 400 == 0) {
return true;
}
return false;
}
public String toString() {
return this.day + "." + this.month + "." + this.year;
}
}
...
public class NextDay {
public static void main(String args[]) throws Exception {
Date dateObj = new Date(20, 5, 2016);
System.out.println("Old Date: " + dateObj.getDay() + "." + dateObj.getMonth() + "." + dateObj.getYear() + ".");
System.out.println("The next day is " + dateObj.getNextDay().toString() + ".");
}
}

You are saying that you want an "or" statement inside switch, right? If you write case labels line by line you get "or statement", like this:
switch(variable){
case 1:
case 2:
case 3: {
//.. when variable equals to 1 or 2 or 3
}
}
So that, you can write your getMaxDaysInMonth method like this:
int getMaxDaysInMonth()
{
int daysInMonth = 0;
switch(month)
{
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
daysInMonth = 31;
break;
case 2:
if(isLeapYear())
{
daysInMonth = 29;
}
else
{
daysInMonth = 28;
}
break;
case 4:
case 6:
case 9:
case 11:
daysInMonth = 30;
}
return daysInMonth;
}
Also, you are checking for the leap year incorrectly. Here's the correct way:
boolean isLeapYear(){
return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
}
And here's how you increment a day:
void incrementDate(){
if((day + 1) > getMaxDaysInMonth())
{
day = 1;
if (month == 12)
{
month = 1;
year++;
}else{
month++;
}
} else {
day++;
}
}

EDIT since we can't just use standard classes
If you have to use switch case, you should use it to set max day in current month and then check, if your current day more than this max day:
int maxDay;
switch (month) {
case 1: maxDay = 31; break;
case 2: maxDay = isLeapYear() ? 29 : 28; break;
case 3: maxDay = 31; break;
// ... other months ...
case 12: maxDay = 31; break;
default: throw new InvalidDateArgumentsException();
}
if (isLeapYear()) {
maxDay = 29;
}
if (day > maxDay) {
throw new InvalidDateArgumentsException();
}

Calculate a day based on user input: always the same day being returned

I am trying to calculate, based on the current day and the number of days in the future a user enters, what day of the week that falls on the calendar. So, for example, today is Friday, or day 5 in my program. If the user enters 15 days ahead, I want it to print that day is Saturday (15 days from today). Unfortunately, I'm getting Friday as the day result no matter how many days ahead are entered. Can someone please help with this? Thank you.
Code so far:
import java.util.*;
import java.text.SimpleDateFormat;
public class DayCalculator {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int userEntryInt;
String dayName;
String userEntry;
String weekdayName = new SimpleDateFormat
("EEEE", Locale.ENGLISH).format(System.currentTimeMillis());
System.out.println("Today is "+weekdayName+".");
System.out.println("Please enter how many days in the past or future "+
"of which you'd like to know the day.");
userEntry = sc.next();
userEntryInt = Integer.parseInt(userEntry);
dayName = getDayNumber(weekdayName, userEntryInt);
System.out.println("Your selected day is a " + dayName +".");
}
//method to calculate new day based on user entry
public static String getDayNumber(String name, int userNumber)
{
String dayNumber = "TEST";
int dayResult = 0;
int dayNumberInt;
switch (name){
case "Monday":
dayNumber = "1";
break;
case "Tuesday":
dayNumber = "2";
break;
case "Wednesday":
dayNumber = "3";
break;
case "Thursday" :
dayNumber = "4";
break;
case "Friday":
dayNumber = "5";
break;
case "Saturday":
dayNumber = "6";
break;
case "Sunday":
dayNumber = "7";
}
System.out.println(dayNumber); //test
dayNumberInt = Integer.parseInt(dayNumber);
System.out.println("dayNumberInt is "+dayNumberInt);//test
System.out.println("dayResult is "+dayResult);//test
if(((dayNumberInt+userNumber)/7)<7)
{
dayResult = dayNumberInt+dayResult;
}
else if (((dayNumberInt+userNumber)/7)>7)
{
dayResult = dayNumberInt-dayResult;
}
if (dayResult <0)
{
dayResult = -dayResult;
}
if (dayResult==0)
{
dayResult = dayNumberInt;
}
String dayNameResult="";
switch (dayResult){
case 1: dayNameResult = "Monday";
break;
case 2: dayNameResult = "Tuedsay";
break;
case 3: dayNameResult = "Wednesday";
break;
case 4: dayNameResult = "Thursday";
break;
case 5: dayNameResult = "Friday";
break;
case 6: dayNameResult = "Saturday";
break;
case 7: dayNameResult = "Sunday";
break;
}
return (dayNameResult);
}
}

What you want to do is take the day of the week it currently is and change it to a number then take that number and add it to the number that the user provided. Then you divide by 7 and find the remainder.
Note:
% is the remainder operator. 10%3=1, 5%3=2, 100%10=0.
For Example:
The day of the week is Monday so that days value would be 1. The user enters 9 so you add 1 and 9 together to get 10. The remainder of dividing 10 by 7 is 3 so the day of the week would be Wednesday.
public static getDayNumber(String name, int userNumber){
if(userNumber<1)
return "Invalid Number";
int dayNumber = 0;
switch(name){
case "Monday":
dayNumber = 1;
break;
case "Tuesday":
dayNumber = 2;
break;
case "Wednesday":
dayNumber = 3;
break;
case "Thursday" :
dayNumber = 4;
break;
case "Friday":
dayNumber = 5;
break;
case "Saturday":
dayNumber = 6;
break;
case "Sunday":
dayNumber = 7;
}
dayNumber = (dayNumber + userNumber)%7;
switch (dayNumber){
case 1: return "Monday";
break;
case 2: return "Tuedsay";
break;
case 3: return "Wednesday";
break;
case 4: return "Thursday";
break;
case 5: return "Friday";
break;
case 6: return "Saturday";
break;
case 7: return "Sunday";
break;
default: return "Invalid Day Provided";
}
}

using hashmap
import java.time.LocalDate;
import java.time.ZoneId;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
public class Solution {
public static void main(String[] args) {
String resultDay=new Solution().solution("Sat",23);
System.out.println(resultDay);
}
public String solution(String S, int K) {
int day = getday(K);
int cDay = listofdays.get(S);
cDay = day + cDay;
cDay = cDay % 7;
return getDayOfWeek(cDay);
}
public static Map<String, Integer> listofdays;
static {
listofdays = new LinkedHashMap<>();
listofdays.put("Sun", 1);
listofdays.put("Mon", 2);
listofdays.put("Tue", 3);
listofdays.put("Wed", 4);
listofdays.put("Thur", 5);
listofdays.put("Fri", 6);
listofdays.put("Sat", 7);
}
static int getday(int k) {
return k % 7;
}
private String getDayOfWeek(int value) {
for (Entry<String, Integer> entry : listofdays.entrySet()) {
if (entry.getValue().equals(value)) {
return entry.getKey();
}
}
return "";
}
}

printing out the day of the week in Java

Im trying to get my program to print out the day of any given date using functions that I have to write and declare, although for the early dates of the month the program doesnt seem to print the write day. The equation in the dayOfTheWeek function, w, was given to us to calculate for the day, although for the 'floor' code to be used i had to create another 'private static' function for reasons im not quite sure of, any reason as to why would be great as well as any reason for why my program isnt returning the right day for certain dates.
here's my code, any help would be greatly appreciated :)
import java.util.Scanner;
import javax.swing.JOptionPane;
public class DayOfTheWeek {
public static final int SEPTEMBER_APRIL_JUNE_NOVEMBER_DAYS = 30;
public static final int REST_OF_YEAR_DAYS = 31;
public static final int LEAP_YEAR_FEB = 29;
public static final int NORMAL_FEB = 28;
public static final int MONTHS = 12;
public static void main(String[] args) {
try
{
String input = JOptionPane.showInputDialog("Enter date (day/month/year):");
Scanner scanner = new Scanner( input );
scanner.useDelimiter("/");
int day = scanner.nextInt();
int month = scanner.nextInt();
int year = scanner.nextInt();
scanner.close();
String numberEnding = numberEnding (day);
String dayEnding = day + numberEnding;
String monthName = monthName (month);
String dayName = dayOfTheWeek (day, month, year);
if (validDate(day, month, year))
{
JOptionPane.showMessageDialog(null, dayName + " " + dayEnding + " " + monthName
+ " " + year + " is a valid date.");
}
else
{
JOptionPane.showMessageDialog(null, "" + dayEnding + " " + monthName
+ " " + year + " is not a valid date.",
"Error", JOptionPane.ERROR_MESSAGE);
}
}
catch (NullPointerException exception)
{
}
catch (java.util.NoSuchElementException exception)
{
JOptionPane.showMessageDialog(null, "No number entered. \nPlease restart and try again.",
"Error", JOptionPane.ERROR_MESSAGE);
}
}
public static boolean validDate( int day, int month, int year ) {
return ((year >= 0) && (month >= 1) && (month <= MONTHS) &&
(day >= 1) && (day <= daysInMonth( month, year )));
}
public static int daysInMonth( int month, int year ) {
int monthDays;
switch (month)
{
case 2:
monthDays = isLeapYear(year) ? LEAP_YEAR_FEB : NORMAL_FEB;
break;
case 4:
case 6:
case 9:
case 11:
monthDays = SEPTEMBER_APRIL_JUNE_NOVEMBER_DAYS;
break;
default:
monthDays = REST_OF_YEAR_DAYS;
}
return monthDays;
}
public static boolean isLeapYear( int year ) {
return (((year%4 == 0) && (year%100 != 0)) || (year%400 == 0));
}
public static String numberEnding( int day ) {
String dayEnding = "";
int remainder = day%10;
if (day >= 10 && day <= 20)
{
dayEnding = "th";
}
else
{
switch (remainder)
{
case 1:
dayEnding = "st";
break;
case 2:
dayEnding = "nd";
break;
case 3:
dayEnding = "rd";
break;
default:
dayEnding = "th";
break;
}
}
return dayEnding;
}
public static String monthName( int month ) {
String monthName = "";
switch (month)
{
case 1:
monthName = "January";
break;
case 2:
monthName = "February";
break;
case 3:
monthName = "March";
break;
case 4:
monthName = "April";
break;
case 5:
monthName = "May";
break;
case 6:
monthName = "June";
break;
case 7:
monthName = "July";
break;
case 8:
monthName = "August";
break;
case 9:
monthName = "September";
break;
case 10:
monthName = "October";
break;
case 11:
monthName = "November";
break;
case 12:
monthName = "December";
break;
default:
}
return monthName;
}
public static String dayOfTheWeek (int day, int month, int year){
String dayName = "";
int Y;
if (month == 1 || month == 2)
{
Y = (year-1);
}
else
{
Y = (year);
}
int y = Y%100;
int c = Y/100;
int w = (day + floor(2.6 * (((month+9) % 12)+ 1) -0.2)
+ y + floor(y/4) + floor(c/4) - (2*c));
w = (w%7);
if (w < 0)
{
w += 7;
}
switch (w)
{
case 0:
dayName = "Sunday";
break;
case 1:
dayName = "Monday";
break;
case 2:
dayName = "Tuesday";
break;
case 3:
dayName = "Wednesday";
break;
case 4:
dayName = "Thursday";
break;
case 5:
dayName = "Friday";
break;
case 6:
dayName = "Saturday";
break;
}
return dayName;
}
private static int floor(double d) {
return 0;
}
}

I believe you need to use the Math.floor() method. Simply call this in place of your floor method:
(day + Math.floor(2.6 * (((month+9) % 12)+ 1) -0.2)
+ y + Math.floor(y/4) + Math.floor(c/4) - (2*c));
You can also cast the equation directly using (int):
int w = (int) (day + 2.6 * ((month+9) % 12 + 1) - 0.2 + y + (y/4) + (c/4) - (2*c));
However, in your case I think that the values will be rounded improperly using casting, so you should probably use the floor method.
If you'd like some additional information on the differences between floor and casting here's a stackoverflow question that addresses it: Cast to int vs floor

I would use the Joda-Time library.
import org.joda.time.DateTime
final DateTime date = new DateTime();
final int dayOfWeek = date.getDayOfWeek();
See the Joda-Time User Guide for more info and examples..