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java Calendar, sum month, year not changing

How can the year in the output add up according to the month's summation?
int sewa = 10
Calendar now = Calendar.getInstance();
int year = now.get(Calendar.YEAR);
String cyear = Integer.toString(year);
int mont = (now.get(Calendar.MONTH) + 1);
String cmont = Integer.toString(mont);
int day = (now.get(Calendar.DATE) );
String cday = Integer.toString(day);
String date = cyear +"/"+cmont+"/"+cday;
Calendar ex = Calendar.getInstance();
int exyear = ex.get(Calendar.YEAR);
String excyear = Integer.toString(exyear);
ex.add(Calendar.MONTH,+sewa);
int exmont = (ex.get(Calendar.MONTH) + 1);
String excmont = Integer.toString(exmont);
int exday = (ex.get(Calendar.DATE) );
String excday = Integer.toString(exday);
String exdate = excyear +"/"+excmont+"/"+excday;
System.out.println(date);
System.out.println("+++++");
System.out.println(exdate);
now : 2018/3/25
+++++ after:2018/1/25
how ouput :2019/1/25

If you are using Java 8 or newer version, please use LocalDate instead of Calendar class. It's very easy to add days, months and years using methods plusDays(), plusMonths() and plusYears(). It's that simple:
LocalDate today = LocalDate.now();
today.plusDays(20);
today.plusMonths(1);
today.plusYears(5);
LocalDate and LocalDateTime were introduced with JSR-310 as much simpler, straightforward and easy to use replacement of Date and Calendar.
However, if you use older version of java, or need to use Date and Calendar for some other reason, you can increase the number of years the same way you did with the months, using
ex.add(Calendar.YEAR, 5);

You capture the year to a variable ...
int exyear = ex.get(Calendar.YEAR);
String excyear = Integer.toString(exyear);
... right before you add 10 months to the calendar ...
ex.add(Calendar.MONTH,+sewa);
... which causes the excyear remains not updated.
To solve it, give the statements a correct order (Get Calendar -> add the months -> get Strings -> print). Or better using SimpleDateFormat:
Calendar ex = Calendar.getInstance();
ex.add(Calendar.MONTH, sewa);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
String exdate = sdf.format(ex.getTime());
System.out.println(exdate);
Prints out:
2019/01/25

Change the Date Format before setText of TextView

I using DatePicker for to choose the date.Everything going good. But the problem is to Format the date.
// display current date
public void setCurrentDateOnView() {
tvDisplayDate = (TextView) findViewById(R.id.tvDate);
final Calendar c = Calendar.getInstance();
year = c.get(Calendar.YEAR);
month = c.get(Calendar.MONTH);
day = c.get(Calendar.DAY_OF_MONTH);
// set current date into textview
tvDisplayDate.setText(new StringBuilder().append(year).append("-").append(month + 1).append("-").append(day).append(" "));
// Month is 0 based, just add 1
}
As per Code i am getting the OUTPUT: 2016-8-22
but
My expected output is 2016-08-22(I want month like this 08)
Thank you,
regards,
Karthi.

Use SimpleDateFormat:
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
tvDisplayDate.setText(sdf.format(c.getTime()));
For more Information about SimpleDateFormat see the official documentation

Try this it may be help to you
public static String updateDate(int day, int month, int year) {
String monthformatted = "";
if (month < 10)
monthformatted = "0" + month;
else
monthformatted = String.valueOf(month);
String dayformatted = "";
if (day < 10)
dayformatted = "0" + day;
else
dayformatted = String.valueOf(day);
// Append in a StringBuilder
String aDate = new StringBuilder().append(year).append('-')
.append(monthformatted).append("-").append(dayformatted).toString();
return aDate;
}
and called this method like
tvDisplayDate.setText(updateDate(day,month+1,year));

private SimpleDateFormat dateFormatter;
dateFormatter = new SimpleDateFormat("dd-MM-yyyy", Locale.US);
tvDisplayDate.setText(dateFormatter.format(newDate.getTime()));
Add this and You will succeed

// display current date
public void setCurrentDateOnView() {
tvDisplayDate = (TextView) findViewById(R.id.tvDate);
final Calendar c = Calendar.getInstance();
year = c.get(Calendar.YEAR);
month = c.get(Calendar.MONTH);
day = c.get(Calendar.DAY_OF_MONTH);
String formattedDate = String.format(Locale.ENGLISH, "%d-%02d-%02d", year, (month + 1), day);
tvDisplayDate.setText(formattedDate);
}

Use SimpleDateFormat class.. There are a lot of ways to do it..
something like this..
SimpleDateFormat sdfSource = new SimpleDateFormat("dd-MM-yy");
// you can add any format..
Date date = sdfSource.parse(strDate);

String format will help you ...
String month=String.format("%02d",cal.get(Calendar.MONTH));
String day=String.format("%02d",cal.get(Calendar.DAY_OF_MONTH)+1);
String year=String.format("%02d",cal.get(Calendar.YEAR));
String full_date = month+ "-" + day + "-" +year ;

You can append zero using String formation
String.format("%02d", month);
// display current date
public void setCurrentDateOnView() {
tvDisplayDate = (TextView) findViewById(R.id.tvDate);
final Calendar c = Calendar.getInstance();
year = c.get(Calendar.YEAR);
month = c.get(Calendar.MONTH);
day = c.get(Calendar.DAY_OF_MONTH);
// set current date into textview
tvDisplayDate.setText(new StringBuilder().append(year).append("-").append(String.format("%02d", month+ 1)).append("-").append(day).append(" "));
// Month is 0 based, just add 1
}
Hope this will help

use the below code to set date as you want
tvDisplayDate.setText(String.format("%04d-%02d-%0d,year,month,date);

tl;dr
LocalDate.now( ZoneId.of( "America/Montreal" ) ).toString()
java.time
You are using troublesome old legacy classes now supplanted by the java.time classes.
Be sure to specify a time zone. If omitted your JVM’s current zone is implicitly applied. That default varies, even during runtime. Better to be specific.
ZoneId z = ZoneId.of( "America/Montreal" );
LocalDate today = LocalDate.now( z );
Or specify the year, month, day-of-month.
LocalDate ld = LocalDate.of( 2016 , 1 , 2 );
The month number is sane, 1-12 for January-December. Alternatively you can pass a Month enum object instead of mere integer.
LocalDate ld = LocalDate.of( 2016 , Month.JANUARY , 2 );
Generate String
The java.time classes use standard ISO formats when parsing and generating strings. That happens to be your desired format.
String output = today.toString();
Same format can be parsed.
LocalDate ld = LocalDate.parse( "2016-01-02" );

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd-MM-yyyy",Locale.US);
tvDisplayDate.setText(simpleDateFormat.format(new Date().getTime()));

how to get month name using current date as input in function

How do I create a function which take current date and return month name?
I have only date its not current date it can be any date like 2013/4/12 or 23/8/8.
Like String monthName("2013/9/11");
when call this function return the month name.

This should be fine.
It depends on the format of date.
If you try with February 1, 2011
it would work, just change this string "MMMM d, yyyy" according to your needs.
Check this for all format patterns.
And also, months are 0 based, so if you want January to be 1, just return month + 1
private static int getMonth(String date) throws ParseException{
Date d = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH).parse(date);
Calendar cal = Calendar.getInstance();
cal.setTime(d);
int month = cal.get(Calendar.MONTH);
return month + 1;
}
If you want month name try this
private static String getMonth(String date) throws ParseException{
Date d = new SimpleDateFormat("MMMM d, yyyy", Locale.ENGLISH).parse(date);
Calendar cal = Calendar.getInstance();
cal.setTime(d);
String monthName = new SimpleDateFormat("MMMM").format(cal.getTime());
return monthName;
}
As I said, check web page I posted for all format patterns. If you want only 3 characters of month, use "MMM" instead of "MMMM"

java.time
I am contributing the modern answer.
System.out.println(LocalDate.of(2013, Month.SEPTEMBER, 11) // Define the date
.getMonth() // Get the month
.getDisplayName( // Get the month name
TextStyle.FULL_STANDALONE, // No abbreviation
Locale.ENGLISH)); // In which language?
Output is:
September
Use LocalDate from java.time, the modern Java date and time API, for a date.
Use LocalDate.getMonth() and Month.getDisplayName() to get the month name.
Avoid Date, Calendar and SimpleDateFormat used in the old answers from 2013. Those classes are poorly designed, troublesome and long outdated. The modern API is so much nicer to work with. Also avoid switch/case for this purpose since the month names are already built in, and using the library methods gives you clearer, terser and less error-prone code.
Use LocalDate
LocalDate today = LocalDate.now(ZoneId.systemDefault());
LocalDate aDate = LocalDate.of(2013, Month.SEPTEMBER, 11); // 2013/9/11
LocalDate anotherDate = LocalDate.of(2023, 8, 8); // 23/8/8
If you are getting the date as string input, parse the string using a DateTimeFormatter:
DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("u/M/d");
String stringInput = "2013/4/12";
LocalDate date = LocalDate.parse(stringInput, dateFormatter);
System.out.println(date);
2013-04-12
Use LocalDate.getMonth() and Month.getDisplayName()
To get the month name you first need to decide in which language you want the month name. I am taking English as an example and still using date from the previous snippet:
String monthName = date.getMonth()
.getDisplayName(TextStyle.FULL_STANDALONE, Locale.ENGLISH);
System.out.println(monthName);
April
Java knows the month names in a wealth of languages. If you want the month name in the user’s language, pass Locale.getDefault() as the second argument to getDisplayName().
Link
Oracle tutorial: Date Time explaining how to use java.time.

Use this code -
Calendar calendar = new GregorianCalendar();
calendar.setTime(date);
int month = calendar.get(Calendar.MONTH);
So now you have month number, you can use switch case to get name for that month.
If your date is in string format use this-
Date date = new SimpleDateFormat("yyyy-MM-dd").format(d)

Simple solution to get current month by name:
SimpleDateFormat formatterMonth = new SimpleDateFormat("MMMM");
String currentMonth = formatterMonth.format(new Date(System.currentTimeMillis()));
Function to get any month by name using format 2013/9/11: (not tested)
private String monthName(String dateToCheck){
Date date = new Date();
SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd");
date = formatter.parse(dateToCheck);
SimpleDateFormat formatterMonth = new SimpleDateFormat("MMMM");
return formatterMonth.format(new Date(date.getTime()));
}

I am using a function like this:
public String getDate(String startDate) throws ParseException {
#SuppressLint("SimpleDateFormat") SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date d = null;
try {
d = sdf.parse(startDate);
sdf.applyPattern("MMMM dd, YYYY"); //this gives output as=> "Month date, year"
} catch (Exception e) {
Log.d("Exception", e.getLocalizedMessage());
}
return sdf.format(d);
}

You can obtain the "number" of the month as described in the other answer and then you could simply use a switch to obtain a name.
Example:
switch(month) {
case 0:
your name is January
break;
...
}
P.S. I think months are zero-based but I'm not 100% sure...

Android: Java SimpleDateFormat: Why February is March?

I can't resolve this question.
I wrote this code:
public static String getMonthName(int year, int month, int day){
Locale locale = Locale.getDefault();
SimpleDateFormat sdf = new SimpleDateFormat("MMMM",locale);
Date date = new Date();
date.setDate(day);
date.setMonth(month);
date.setYear(year);
return sdf.format(date);
}
It works very well but when month = 1 (that is February), month name is March and not February! Why?
This code works very well for all other days and months...
There is another way to get translated month name?
Please help me....

Depending on how you call your function (eg using current day as the 29 of Feb which doesn't exist in 2013), you may make the month being incremented automatically.
I'd suggest the use of this function which avoids the problem :
public static String getMonthName(int month){
Locale locale = Locale.getDefault();
SimpleDateFormat sdf = new SimpleDateFormat("MMMM",locale);
Date date = new Date();
date.setDate(1);
date.setMonth(month);
date.setYear(2012);
return sdf.format(date);
}

This is because the months start from zero index, So you should use this logic
if(day >0)
{
day =day -1;
}

Android : date format in a String

I have a problem to sort date because of the format of these dates.
I obtain the date :
final Calendar c = Calendar.getInstance();
mYear = c.get(Calendar.YEAR);
mMonth = c.get(Calendar.MONTH);
mDay = c.get(Calendar.DAY_OF_MONTH);
And I build a String with these values.
dateRappDB = (new StringBuilder()
.append(mYear).append(".")
.append(mMonth + 1).append(".")
.append(mDay).append(" ")).toString();
The problem is that if the month is for example February, mMonth value is 2. So dates with months like October (10) comes before in my list.
What I need is that month and day are formated like MM and dd. But I don't know how to do it in my case.
EDIT :
I solved the problem by using a DateFormat like said above.
I replaced this :
dateRappDB = (new StringBuilder()
.append(mYear).append(".")
.append(mMonth + 1).append(".")
.append(mDay).append(" ")).toString();
By this :
Date date = new Date(mYear - 1900, mMonth, mDay);
dateFacDB = DateFormat.format("yyyy.MM.dd", date).toString();
And it works.
Thanks to all of you for your help :)

here is a simple way to convert Date to String :
SimpleDateFormat simpleDate = new SimpleDateFormat("dd/MM/yyyy");
String strDt = simpleDate.format(dt);

Calendar calendar = Calendar.getInstance();
Date now = calendar.getTime();
String timestamp = simpleDateFormat.format(now);
These might come in handy
SimpleDateFormat simpleDateFormat =
new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSSSSZZZZZ");
this format is equal to --> "2016-01-01T09:30:00.000000+01:00"
SimpleDateFormat simpleDateFormat =
new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZZZZZ");
this format is equal to --> "2016-06-01T09:30:00+01:00"

here is the example for date format
SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
Date date = new Date();
System.out.println("format 1 " + sdf.format(date));
sdf.applyPattern("E MMM dd yyyy");
System.out.println("format 2 " + sdf.format(date));

You need to sort dates, not strings. Also, have you heared about DateFormat? It makes all that appends for you.

If I understand your issue, you create a list of dates and since they're strings, they get arranged in a dictionary-order number-wise, which means you get october before february (10 before 2).
If I were you, I would store my results in a container where I control the insertion point (like an array list) or where I can control the sorting algorithm.