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How to get user's timezone and convert time saved in database according to the user's timezone? Please see details

I'm developing an app in which I'm saving the time when the post was posted.
I'm getting that time by using this code:
DateFormat currentTime = new SimpleDateFormat("h:mm a");
final String time = currentTime.format(Calendar.getInstance().getTime());
Now, what I want is I want to get user's timezone and convert the time saved in database using his/her timezone to his/her local time.
I tried doing this using code:
public String convertTime(Date d) {
//You are getting server date as argument, parse your server response and then pass date to this method
SimpleDateFormat sdfAmerica = new SimpleDateFormat("h:mm a");
String actualTime = sdfAmerica.format(d);
//Changed timezone
TimeZone tzInAmerica = TimeZone.getDefault();
sdfAmerica.setTimeZone(tzInAmerica);
convertedTime = sdfAmerica.format(d);
Toast.makeText(getBaseContext(), "actual : " + actualTime + " converted " + convertedTime, Toast.LENGTH_LONG).show();
return convertedTime;
}
but this is not changing the time.
This is how I'm trying to convert time saved in database using above method (postedAtTime is the time which is getting retrieved from database):
String timeStr = postedAtTime;
SimpleDateFormat df = new SimpleDateFormat("h:mm a");
Date date = null;
try {
date = df.parse(timeStr);
} catch (ParseException e) {
e.printStackTrace();
}
convertTime(date);
Please let me know what's wrong in my code or if this is wrong way?

The time string you're storing is not sufficient to be able to change timezones after the fact (h:mm a is only hours, minutes and am/pm marker). In order to do something like this you need to either store the timezone the original timestamp was in or better yet store the time in a deterministic manner like always UTC.
Example code:
final Date now = new Date();
final String format = "yyyy-MM-dd HH:mm:ss";
final SimpleDateFormat sdf = new SimpleDateFormat(format, Locale.US);
// Convert to UTC for persistence
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
// Persist string to DB - UTC timezone
final String persisted = sdf.format(now);
System.out.println(String.format(Locale.US, "Date is: %s", persisted));
// Parse string from DB - UTC timezone
final Date parsed = sdf.parse(persisted);
// Now convert to whatever timezone for display purposes
final SimpleDateFormat displayFormat = new SimpleDateFormat("HH:mm a Z", Locale.US);
displayFormat.setTimeZone(TimeZone.getTimeZone("America/New_York"));
final String display = displayFormat.format(parsed);
System.out.println(String.format(Locale.US, "Date is: %s", display));
Output
Date is: 2016-06-24 17:49:43
Date is: 13:49 PM -0400

Format date like system format using Time.getCurrentTimezone()

I'm using Time.getCurrentTimezone()to get the current timezone and therefore the date.
I'm getting and formatting it like this:
private void setDate() {
Time today = new Time(Time.getCurrentTimezone());
today.setToNow();
tvdate2.setText(today.monthDay + "-" + today.month + "-" + today.year);
}
How can I format the date according to the system settings?
I didn't manage to get it done via SimpleDateFormat...

You could get time in any format by using SimpleDateFormat class. Please refer to this
Calendar cal = Calendar.getInstance();
String currentDate = cal.get(Calendar.DAY_OF_MONTH)+"/"+(cal.get(Calendar.MONTH)+1)+"/"+cal.get(Calendar.YEAR);
Date date = new SimpleDateFormat("dd/MM/yyyy HH:mm", Locale.ENGLISH).parse(currentDate);

How to get Date object in “YYYY-MM-DD” format in android

I have a requirement that I need to compare two Dates. One Date will come from DB which is String in "YYYY-DD-MM" firm and I need to compare this String Date with current Date.
for this I am converting Date String into Date object.
Now I need current Date also in "YYYY-MM-DD" format and it should be Date object so that I can use.compareTo() method compare two dates..
Please help me how to do that...

Date cDate = new Date();
String fDate = new SimpleDateFormat("yyyy-MM-dd").format(cDate);

You can do it in following way
// pick current system date
Date dt = new Date();
// set format for date
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
// parse it like
String check = dateFormat.format(dt);
System.out.println("DATE TO FROM DATEBASE " +
arrayOfStringDate[d].toString());
System.out.println("CURRENT DATE " + check);
// and compare like
System.out.println("compare "+
arrayOfStringDate[d].toString().equals(check));

Calendar c = Calendar.getInstance();
SimpleDateFormat tf = new SimpleDateFormat("yyyy-MM-dd");
String time=DB time;
Date parseTime= tf.parse(time);
Integer dayNow=c.getTime().getDate();
Integer dayDb=parseTime.getDate();
then you can compare dayNow and dayDb.

If your current date is actually an instance of the java.util.Date class, you don't need to specify a format for it; it's just a millisecond value that represents a specific moment in time.
You can get the current date like so:
Date currentDate = new Date();

You can use 2 ways:
DateFormat object. Use parse method.
Make your own parser of the Date. I mean, you convert the year, month and day in an integer each, and use Date constructor to get the Date.

How to Compare system date with mydate in android 2.1?

in my Android application, i am taking date and time from database. but i am not able to get the date in the "Date" Format from the database into my application, the date is in string format, so i am not able to compare the system date to database date.
if i convert the system date into string then i am not able to update the date into the database in recurring case. i also want to update the database date if the system date and database date is matched.
how can i achieve this is android.
Thanks in advance.

You can convert String to Date like this:
String str = "12/12/1912";
SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
Date date = formatter.parse(str);
And back to String
SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
System.out.println("Date is : " + formatter.format(date));
And Date has before and after methods and can be compared to each other.
By the way there is also a library called Joda, you can also check it out.

Try this code:
Calendar c = Calendar.getInstance();
System.out.println("Current time => " + c.getTime());
SimpleDateFormat df = new SimpleDateFormat("dd-MMMM");
formattedDate = df.format(c.getTime());

Android load timezone too long: Loaded time zone names for en_US

Dear all, i just code a snippet code to get date time string as below:
public static String getCurrentDate(){
Locale.setDefault(Locale.US);
Date date = new Date();
String strDate = date.toString();
return strDate;
}
But problem is it take too long time (about 2 seconds) to convert from Date to string, Logs:
10-11 17:52:51.733: INFO/Resources(6835): Loaded time zone names for en_US in 2107ms.
Could you please give me a solution how to increase performance of this method
Update for solution:
I just found an solution by tronman at topic:
How do you format date and time in Android?
As below:
Date date = new Date();
java.text.DateFormat dateFormat =
android.text.format.DateFormat.getDateFormat(getApplicationContext());
mTimeText.setText("Time: " + dateFormat.format(date));

Yet another solution is to use SimpleDateFormat with default locale
new SimpleDateFormat("dd/MM", Locale.getDefault());