Print current month and the next two months

Question

I’m taking the current month in number and need to increment it two more months ahead, besides using the current month and saving in a string array.

I’m taking the whole and retrieving the name of the month, but even taking numbers other than 12, he insists on writing "DEZ". Does anyone know another method of recovering the month written in full?

Follow the code snippet:

int mes = calendar.get(GregorianCalendar.MONTH);
for (int i = 0; i < quantidadeMeses; i++) {
   Locale local = new Locale("pt", "BR");
   DateFormat dateFormat = new SimpleDateFormat("MMM", local);
   axisData[i] = dateFormat.format(mes + i).toUpperCase();
}

Answer 1

If you want to add months to one Calendar, use the method add, informing the field you want to add (in case, how I want to add the month, use Calendar.MONTH):

Calendar calendar = Calendar.getInstance();
int quantidadeMeses = 3;
Locale local = new Locale("pt", "BR");
DateFormat dateFormat = new SimpleDateFormat("MMM", local);
for (int i = 0; i < quantidadeMeses; i++) {
    // imprime a data correspondente ao Calendar
    System.out.println(dateFormat.format(calendar.getTime()).toUpperCase());
    calendar.add(Calendar.MONTH, 1); // soma 1 mês
}

In the above case, the Calendar begins with today’s date (September), and within the for i print the date and then add 1 month. The result is:

SET
OUT
NOV

Also note that you don’t need to create the SimpleDateFormat within the for, just create it once before the loop and reuse it at each iteration.

Besides, I use the method getTime(), that returns a java.util.Date, so that this is passed to the method format.

---

java.time

If using Java >= 8 and your code does not depend on the use of Date and Calendar, an alternative is to use the API java.time, which is more modern and solves many of the old API problems.

In your case, you could use a java.time.LocalDate to save the date, use the method plusMonths to add months, and format the date with a java.time.format.DateTimeFormatter:

LocalDate data = LocalDate.now();
int quantidadeMeses = 3;
Locale local = new Locale("pt", "BR");
DateTimeFormatter fmt = DateTimeFormatter.ofPattern("MMM", local);
for (int i = 0; i < quantidadeMeses; i++) {
    System.out.println(fmt.format(data).toUpperCase());
    data = data.plusMonths(1); // somar 1 mês
}

Note that when adding 1 month I had to assign the return to the variable data. This is because the classes of java.time are immutable, and methods such as plusMonths always return another instance with the modified values. The output is the same as the code with Calendar.

Like the java.time possesses several different classes to represent dates and times, you can also choose to use other of them depending on what you need.

In this case, if you don’t need the exact date (day, month and year), you could use a java.time.YearMonth, which is a class that keeps only the month and year. Its operation is very similar to LocalDate, because she also owns the method plusMonths:

YearMonth data = YearMonth.now();
int quantidadeMeses = 3;
Locale local = new Locale("pt", "BR");
DateTimeFormatter fmt = DateTimeFormatter.ofPattern("MMM", local);
for (int i = 0; i < quantidadeMeses; i++) {
    System.out.println(fmt.format(data).toUpperCase());
    data = data.plusMonths(1); // somar 1 mês
}

Another alternative is to get the current date and extract only the month, getting a java.time.Month, which in turn possesses the method plus to add months:

Month mes = LocalDate.now().getMonth();
int quantidadeMeses = 3;
Locale local = new Locale("pt", "BR");
DateTimeFormatter fmt = DateTimeFormatter.ofPattern("MMM", local);
for (int i = 0; i < quantidadeMeses; i++) {
    System.out.println(fmt.format(mes).toUpperCase());
    mes = mes.plus(1); // somar 1 mês
}

And in this case, it would also be possible to use the method getDisplayName, instead of using a DateTimeFormatter:

Month mes = LocalDate.now().getMonth();
int quantidadeMeses = 3;
Locale local = new Locale("pt", "BR");
for (int i = 0; i < quantidadeMeses; i++) {
    System.out.println(mes.getDisplayName(TextStyle.SHORT, local).toUpperCase());
    mes = mes.plus(1); // somar 1 mês
}

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If you don’t already use Java 8, you can use Threeten Backport, which has the same classes already mentioned (LocalDate, DateTimeFormatter, etc) and it basically works the same way. The difference is that they are in the package org.threeten.bp (instead of java.time). The backport is compatible with JDK 6 and 7.

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In case you are still attached to Java 5 and want to use something better than Date and Calendar, an alternative is the Joda-Time (although this is a project considered "terminated", since on your site there’s a warning indicating this and recommending the use of java.time)

Joda-Time has classes with names similar to java.time, although it is not 100% equal. Classes are in the package org.joda.time, follows a similar example to the previous code:

import org.joda.time.LocalDate;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

...
LocalDate date = new LocalDate();
Locale local = new Locale("pt", "BR");
DateTimeFormatter fmt = DateTimeFormat.forPattern("MMM").withLocale(local);
int quantidadeMeses = 3;
for (int i = 0; i < quantidadeMeses; i++) {
    System.out.println(fmt.print(date).toUpperCase());
    date = date.plusMonths(1);
}

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More about the java.time can be seen in this question.

Answer 2

If you are using Java 8+, I suggest you read about LocalDate. With the LocalDate Easily you can make the following code.

LocalDate hoje = LocalDate.now();
LocalDate proximoMes = LocalDate.now().plusMonths(1);
LocalDate segundoMesAFrente = LocalDate.now().plusMonths(2);

Here is the link of documentation.