Develop Reference

The method getTime() is undefined for the type Object — what’s wrong?

I have created an application that generates a difference between two dates when u click on a button named "calculate difference", but I don't know whats wrong with this code. I tried different methods and without any result. If you can help me I will be grateful guys.
public class DateForm extends javax.swing.JPanel {
String date1 = "26/02/2011";
String time1 = "11:00 AM";
String date2 = "27/02/2011";
String time2 = "12:15 AM";
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy hh:mm a");
private Object dateObj1;
private Object dateObj2;
public DateForm() {
initComponents();
}
private void btnActionPerformed(java.awt.event.ActionEvent evt) {
try {
Date dateObj1 = sdf.parse(date1 + " " + time1);
} catch (ParseException ex) {
Logger.getLogger(DateForm.class.getName()).log(Level.SEVERE, null, ex);
}
try {
Date dateObj2 = sdf.parse(date2 + " " + time2); // TODO add your handling code here:
} catch (ParseException ex) {
Logger.getLogger(DateForm.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println(dateObj1);
System.out.println(dateObj2);
long diff = dateObj2.getTime() - dateObj1.getTime();
double diffInHours = diff / ((double) 1000 * 60 * 60);
System.out.println(diffInHours);
System.out.println("Hours " + (int)diffInHours);
System.out.println("Minutes " + (diffInHours - (int)diffInHours)*60 );
}
}

Since it's 2018, you really should be making use of the date/time APIs introduced in Java 8 (or the ThreeTen Backport if you're Java 7 or below)
String date1 = "26/02/2011";
String time1 = "11:00 AM";
String date2 = "27/02/2011";
String time2 = "12:15 AM";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy hh:mm a");
LocalDateTime start = LocalDateTime.parse(date1 + " " + time1, formatter);
LocalDateTime end = LocalDateTime.parse(date2 + " " + time2, formatter);
Duration duration = Duration.between(start, end);
long hours = duration.toHours();
long mins = duration.minusHours(hours).toMinutes();
// Or if you're using Java 9+
//long mins = duration.toMinutesPart();
System.out.println("Hours = " + hours);
System.out.println("Mins = " + mins);
which ouputs
Hours = 13
Mins = 15
I would recommend having a read of Date and Time Classes
"whats wrong with this code please?"
The following...
try {
Date dateObj1 = sdf.parse(date1 + " " + time1);
} catch (ParseException ex) {
Logger.getLogger(DateForm.class.getName()).log(Level.SEVERE, null, ex);
}
try {
Date dateObj2 = sdf.parse(date2 + " " + time2); // TODO add your handling code here:
} catch (ParseException ex) {
Logger.getLogger(DateForm.class.getName()).log(Level.SEVERE, null, ex);
}
Is simply creating two objects whose scope is only relevant to the try-catch blocks they are defined in, dateObj1 and dateObj2 can't be accessed outside of those blocks ... but ...
You define...
private Object dateObj1;
private Object dateObj2;
as instance fields, which means...
System.out.println(dateObj1);
System.out.println(dateObj2);
will most likely print null and...
long diff = dateObj2.getTime() - dateObj1.getTime();
won't compile, because dateObj1 and dateObj2 are just defined as Object and Object doesn't have a getTime method
Date/time calculations are complex and governed by many different rules (further complicated by the type of calendar you are using)
Simply doing...
double diffInHours = diff / ((double) 1000 * 60 * 60);
is naive at best, broken at worst
And...
System.out.println("Minutes " + (diffInHours - (int)diffInHours)*60 );
is well, pointless, what's (something - something) * 60?

MadProgrammer’s answer is a very good one. I’d just like to supply a detail: Depending on taste you may parse the date and time strings separately and combine them after parsing:
DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("dd/MM/uuuu");
DateTimeFormatter timeFormatter
= DateTimeFormatter.ofPattern("hh:mm a", Locale.ENGLISH);
String date1 = "26/02/2011";
String time1 = "11:00 AM";
LocalDateTime start = LocalDate.parse(date1, dateFormatter)
.atTime(LocalTime.parse(time1, timeFormatter));
System.out.println(start);
Output is:
2011-02-26T11:00
One potential advantage is in case of a bug in one of the parsed string you will get a preciser error message.
And one more detail now I’m at it: specify locale. AM and PM are called other things in other languages, so to make sure that your code works on other computers and also on the day when you play with your regional settings…

Java Joda time isAfter date solution

I want to compare two dates.
If the current date time is greater or after the
specific date , then it will return 'True'.
So far I have tried this.
String deadline = "25/11/2017 11:00:00";
DateTime utc = new DateTime(DateTimeZone.UTC);
DateTimeZone timeZone = DateTimeZone.forID("Asia/Dhaka");
DateTime dhakaTime = utc.toDateTime(timeZone);
//Dead Line Time
DateTimeFormatter format = DateTimeFormat.forPattern("dd/MM/yyyy HH:mm:ss");
DateTime deadlineTime = format.parseDateTime(deadline.trim());
//Comapare
return deadlineTime.isAfter(dhakaTime.plusDays(2));
As today is 23 and dhakaTime.plusDays(2) will be 25 so it should return
"true".
But I am getting "false".
Output value :
dhakaTime.plusDays(2) = 2017-11-25T14:10:27.762+06:00
deadlineTime = 2017-11-25T11:00:00.000+06:00
Am i missing something or doing something wrong?

It gives false correctly.
You're comparing
deadLineTime = 2017-11-25T11:00:00.000+06:00 and
dhakaTime(+2) = 2017-11-25T14:10:27.762+06:00
They both are at same date, but with time, deadLineTime is at 11AM but dhakaTime(+2) is at 2PM. So,
(Nov 25, 2017 11AM)isAfter(Nov 25, 2017 2PM) is false.
EDIT: Testcases
As you mentioned you're testing, The following used different test cases for comparing deadLine with dhakaTime (+1, and +2 days). I hope this gives you an idea about how this works.
public static void main(String[] args) {
String deadline = "25/11/2017 11:00:00";
DateTime utc = new DateTime(DateTimeZone.UTC);
DateTimeZone timeZone = DateTimeZone.forID("Asia/Dhaka");
DateTime dhakaTime = utc.toDateTime(timeZone);
//Dead Line Time
DateTimeFormatter format = DateTimeFormat.forPattern("dd/MM/yyyy HH:mm:ss");
DateTime deadlineTime = format.parseDateTime(deadline.trim());
System.out.println("Deadline : " + deadline);
System.out.println("Current datetim : " + dhakaTime);
System.out.println("current datetime + 1 day : " + dhakaTime.plusDays(1));
System.out.println("current datetime + 2 day : " + dhakaTime.plusDays(2));
System.out.println("Is deadline after current datetime:" + deadlineTime.isAfter(dhakaTime));
System.out.println("Is deadline after current datetime + 1 day:" + deadlineTime.isAfter(dhakaTime.plusDays(1)));
System.out.println("Is deadline after current datetime + 2 day:" + deadlineTime.isAfter(dhakaTime.plusDays(2)));
}

Try using the method DateTimeFormatter withZone(DateTimeZone zone) and use that to create the DateTime

Android Time UTC

I am working on an Android app that frequently travels from Time Zone to TZ. I am getting various errors with times and TZs. The latest error is, when I load the flat file with times (see below), everything looks good. When I save the app environment (aka all variables/objects to sharedprefs), stop and then restart the app the time displayed is no longer local but UTC.
I began developing the app just using the default/local TZ. However, this became very complicated with DST and various TZs. Therefore my current approach is to store time in the app in UTC, and calculate differences between UTC times as needed. Then convert the UTC-stored time to the local TZ on-demand for user interaction.
I recognize there are many posts related to android time. I think I have read most if not all on java.util.date and Joda. However, I am still stuck. So, here goes...
I have 3 sources of time for the app. 1) I read in UTC Strings from a flat file 2) I get milliseconds since the Epoch for system time stamp (in UTC). 3) I get UTC in a string via a rest API. The app does numerous calculations between the 3 categories such as time difference, add time, etc. Below I will post my code for each of these
1 - Convert string UTCs that come from a file
public static Date string2date(String strformat, String strdate){
Date tdate = timestamp();
TimeZone tz = TimeZone.getDefault() ;
TimeZone.setDefault(TimeZone.getTimeZone("UTC"));
SimpleDateFormat formatter = new SimpleDateFormat(strformat);
formatter.setTimeZone(TimeZone.getTimeZone("UTC"));
String dateInString = strdate;
try {
tdate = formatter.parse(dateInString);
} catch (ParseException e) {
e.printStackTrace();
}
return tdate;
}
2 - Get milliseconds since Epoch
public static Date timestamp() {
Calendar localCalendar = Calendar.getInstance(TimeZone.getDefault());
//Date currentTime = localCalendar.getTime();
Date currentTime = GetUTCdatetimeAsDate();
return currentTime;
public static Date GetUTCdatetimeAsDate()
{
//note: doesn't check for null
return StringDateToDate(GetUTCdatetimeAsString());
}
public static String GetUTCdatetimeAsString()
{
final SimpleDateFormat sdf = new SimpleDateFormat(longdt);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
final String utcTime = sdf.format(new Date());
return utcTime;
}
public static Date StringDateToDate(String StrDate)
{
Date dateToReturn = null;
SimpleDateFormat dateFormat = new SimpleDateFormat(longdt);
try
{
dateToReturn = (Date)dateFormat.parse(StrDate);
}
catch (ParseException e)
{
e.printStackTrace();
}
return dateToReturn;
}
3 - Get UTC in a string via a rest API (Format is "2017-02-10T01:09:00Z")
try {
Calendar tempCal = ISO8601.toCalendar(dateLocal);
Log.e (" fbu "," fsutc " + tempCal.getTime() );
ISODepDate = tempCal.getTime();
tempCal = ISO8601.toCalendar(dateLocal2);
ISOArrDate = tempCal.getTime();
//ab.setTimeZone(PST);
Log.e (" fbu "," fsutc " + dateLocal + " / " + dateLocal2);
Log.e (" fbu "," fsutc " + ISODepDate + " / " + ISOArrDate);
}
catch (Exception a){
int aa = 1;
Log.e (" exception "," a " + a);
}
public static Calendar toCalendar(final String iso8601string)
throws ParseException {
Calendar calendar = GregorianCalendar.getInstance();
TimeZone tz = TimeZone.getDefault() ;
TimeZone.setDefault(TimeZone.getTimeZone("UTC"));
String s = iso8601string.replace(".000Z", "+00:00");
try {
s = s.substring(0, 22) + s.substring(23); // to get rid of the ":"
} catch (IndexOutOfBoundsException e) {
throw new ParseException("Invalid length", 0);
}
Date date = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ").parse(s);
calendar.setTime(date);
return calendar;
}
4 - Finally, here is what I am using to "Display" the above 3 time categories in local time.
public String UTCtoLocal(Date indate, Boolean formatLong) {
Date utcDate = indate;
String result;
//Log.e( " utc "," indate " + indate);
/*utcDate = your own initialization here;*/
Date localDate = new Date(utcDate.getTime() + TimeZone.getDefault().getRawOffset());
//Log.e( " utc "," localdate " + localDate);
if (formatLong){
result = longd.format(localDate);
} else {
result = shortt.format(localDate);
}
return result;
The questions are, given the expectation that I store in UTC and display in Local, a) Have I implemented items 1-4 correctly? b) Will the above code actually store the times in UTC and display in local?
After flat file load everything looks good. After restart the times are displayed in UTC vs Local.

trying to fix a dereferencing error in java

I have a problem where i'm trying to find the date and time for a specific long value from the "new beginning of the universe", aka jan 1 1970.
I get a "cannot be dereferenced" error when i try to pass my new value to the toString thing.
What i don't get, is that this works for getting a time in millis and displaying it a more readable date/time format, so why not after i do a bunch of math with it?
import java.util.*;
public class Date {
public static void main(String[] args) {
Date mydate1 = new Date(10000);
System.out.println("The date and time of " +
mydate1.elapse + " from the Unix epoch is " + mydate1.getMyTime());
Date mydate2 = new Date(100000);
System.out.println("The date and time of " +
mydate2.elapse + " from the Unix epoch is " + mydate2.getMyTime());
Date mydate3 = new Date(1000000);
System.out.println("The date and time of " +
mydate3.elapse + " from the Unix epoch is " + mydate3.getMyTime());
Date mydate4 = new Date(10000000);
System.out.println("The date and time of " +
mydate4.elapse + " from the Unix epoch is " + mydate4.getMyTime());
Date mydate5 = new Date(100000000);
System.out.println("The date and time of " +
mydate5.elapse + " from the Unix epoch is " + mydate5.getMyTime());
Date mydate6 = new Date(1000000000);
System.out.println("The date and time of " +
mydate6.elapse + " from the Unix epoch is " + mydate6.getMyTime());
/*Date date7 = new Date(10000000000);
System.out.println("The date and time of " +
date7.elapse + " from the Unix epoch is " + date7.getTime());
Date date8 = new Date(100000000000);
System.out.println("The date and time of " +
date8.elapse + " from the Unix epoch is " + date8.getTime());*/
}
long elapse;
Date() {
elapse = 1;
}
Date(long elapseTime) {
elapse = elapseTime;
}
long getMyTime() {
//java.util.Date date = new.java.util.Date();
long currentMillis = System.currentTimeMillis();
long date = currentMillis + elapse - currentMillis;
System.out.println(date.toString());

You can't call toString() on a long (primitive type) -
// System.out.println(date.toString());
System.out.println(date); // <-- this would work.
System.out.println(String.valueOf(date)); // <-- this would be assignable to a
// String, but it prints the
// same value as the first example.

In
long date = currentMillis + elapse - currentMillis;
The variable date is a primitive (long) and not a object. toString is a method all java classes inherit from java.lang.Object and so will be available in all objects (that are instance of classes). long is just a primitive, primitives do not have methods, they do not inherit from Object either.
So all you need is
System.out.println(date);

The issue is in : System.out.println(date.toString())
date is of primitive type long (its not an object of wrapper class Long). Hence the method toString() is not available for 'date'. rather you can simple use :
System.out.println(date);
If you want to print the formatted Date use the following :
Dste d = new Date(date);
SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy hh:mm:ss");
System.out.println(sdf.format(d));

How to find the days between dates using my code?

Below is my code which checks the date which is stored in database with the current system date and calculates the days and if that days is lesser than the 180 days it will print something else print nothing,this code works great in an normal java program(with out using swings concept) if it is used with the swing program i changed the sql query to check get the date from the database based on the department and staff names which is entered in the text fields,i coded this code inside an jbutton,in the output it just prints the current system date but not calculates the days between the selected date and the current system dates,friends this is the problem am facing kindly need your help friends....thanks in advance..
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
try {
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/leave", "root", "");
Statement stm = conn.createStatement();
ResultSet rs = stm.executeQuery("select * from staff where depmt='" + txt1 + "' AND staffs='" + txt2 + "'");
Calendar javaCalendar = null;
String currentDate = "";
javaCalendar = Calendar.getInstance();
currentDate = javaCalendar.get(Calendar.DATE) + "/" + (javaCalendar.get(Calendar.MONTH) + 1) + "/" + javaCalendar.get(Calendar.YEAR);
int cdate = javaCalendar.get(Calendar.DATE);
int cmonth = (javaCalendar.get(Calendar.MONTH) + 1);
int cyear = javaCalendar.get(Calendar.YEAR);
int z = 0;
int date = 0, month = 0, year = 0;
System.out.println("Current Date\t" + currentDate);
System.out.println("\n");
while (rs.next()) {
date = rs.getInt(3);
month = rs.getInt(4);
year = rs.getInt(5);
System.out.println("Random Date\t" + date + "/" + month + "/" + year + "\n");
int d = (date - cdate);
int m = month - cmonth;
int y = year - cyear;
int d1 = java.lang.Math.abs(d);
int d2 = java.lang.Math.abs(m);
int d3 = java.lang.Math.abs(y);
z = d1 + (d2 * 30) + (d3 * 365);
if (z >= 180) {
System.out.println("something");
0
} else {
System.out.println("nothing");
}
}
} catch (Exception e) {
System.out.println(e.getMessage());
//e.printStackTrace();
}
// TODO add your handling code here:
}

You should really use prepared statements cause this way your query is prone to sql injections.
Date formatter insted of concating string for currentdate
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
String formattedDate = formatter.format(todaysDate);
Also it seems like your not closeing the connection that may be another issue.
Is there any reason for storeing the date in 3 separate columns?

Your algorithm to calculate the day difference between two dates is broken. It does not take in account different month lengths or leap years.
Unfortunately Java Calendar does not offer this feature at all. So either you apply your own homegrown algorithm (not easy, but in web there are some sources how to map a gregorian date to epoch days) or you use JodaTime like this way:
LocalDate db = new LocalDate(year, month, date);
int days = Days.daysBetween(db, LocalDate.now()).getDays();
Note that the result will be negative if db date is in the future. After all you can greatly shorten your code and abandon all Calendar stuff which is very bad for calculations of durations.

try this:
DateFormat df = new SimpleDateFormat("dd/MM/yyyy");
Date date1 = df.parse("14/02/2014");
Date date2 = df.parse("08/03/2014");
int days = Days.daysBetween(date1, date2).getDays();

Try this, by changing return value from millisecond to day.
public static int daysBetween(Date dateFrom, Date dateTo){
return (int)( (dateTo.getTime() - dateFrom.getTime()) / (1000 * 60 * 60 * 24));
}

Start Of Day
If you start with a mid-afternoon date-time object, go back 180 days by calculating seconds * minutes * hours * 180, you'll end up excluding the date-times earlier in that day 180 ago whereas I suppose you would want to include them. You should pay attention to when the day begins.
Time Zone
Both the question and other answers ignore the issue of time zone. Time zone defines the beginning of a day. Given the point about start of day (above), time zone is a related component.
Avoid java.util.Date & .Calendar
The java.util.Date and .Calendar classes bundled with Java are notoriously troublesome. Avoid them. Instead use either Joda-Time or the new java.time package in Java 8.
Joda-Time
Here is some example code using Joda-Time 2.3.
Note that while a Joda-Time DateTime object is similar to a java.util.Date, a DateTime does truly know its own assigned time zone.
DateTimeZone timeZone = DateTimeZone.forID( "Europe/Paris" );
DateTime dateTimeInQuestion = new DateTime( 2013, 6, 5, 4, 3, 2, timeZone );
DateTime now = new DateTime( timeZone );
DateTime hundredEightyDaysAgo = now.minusDays( 180 ).withTimeAtStartOfDay();
boolean isExpired = dateTimeInQuestion.isBefore( hundredEightyDaysAgo );
Dump to console…
System.out.println( "dateTimeInQuestion: " + dateTimeInQuestion );
System.out.println( "now: " + now );
System.out.println( "hundredEightyDaysAgo: " + hundredEightyDaysAgo );
System.out.println( "isExpired: " + isExpired );
When run…
dateTimeInQuestion: 2013-06-05T04:03:02.000+02:00
now: 2014-03-10T07:34:26.937+01:00
hundredEightyDaysAgo: 2013-09-11T00:00:00.000+02:00
isExpired: true