What do we mean by -Xdiags:verbos?

Question

While using Calendar class of java I am getting an error, the term -Xdiags:verbos is there in error message

Code:

public class CalendarClass{
    public static void main(String args[]){
       Calendar cal=Calendar.getInstance();
       System.out.println(cal.get(Calendar.DATE+ " / "+ Calendar.MONTH + " / " + Calendar.YEAR )); 
    }
    
} 

Output:

CalendarClass.java:5: error: incompatible types: String cannot be converted to int System.out.println(cal.get(Calendar.DATE+ " / "+ Calendar.MONTH + " / " + Calendar.YEAR )); ^ Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output

So how I should resolve this?

Answer 1

You can't create a new syntax for Calendar.get(int) (it takes an int, not a String). Change

System.out.println(cal.get(Calendar.DATE+ " / "
        + Calendar.MONTH + " / " + Calendar.YEAR ));

to

System.out.println(cal.get(Calendar.DAY_OF_MONTH) 
        + " / " + (cal.get(Calendar.MONTH) + 1) + " / "
        + cal.get(Calendar.YEAR));

But I would strongly suggest you replace all of that with the more modern java.time equivalent. Like,

System.out.println(DateTimeFormatter.ofPattern("dd / M / yyyy")
        .format(LocalDate.now()));

Both of which output (because today is January 30, 2022)

30 / 1 / 2022

Answer 2

The main issue is answered already. Calendar.get needs an int as parameter but your code delivers a String from the string concatenation Calendar.DATE+ " / " + Calendar.MONTH + " / " + Calendar.YEAR.

To answer your question about the note

Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output

It tells you that you could get a more verbose diagnostic mode while compiling when you add extra option -Xdiags:verbose to javac. In concrete example:

Without -Xdiags:verbose:

CalendarClass.java:N: error: incompatible types: String cannot be converted to int
       System.out.println(cal.get(Calendar.DATE+ " / " + Calendar.MONTH + " / " + Calendar.YEAR ));
                                                                                ^
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
1 error

The message points to the last + in string concatenation.

With -Xdiags:verbose:

CalendarClass.java:N: error: method get in class Calendar cannot be applied to given types;
       System.out.println(cal.get(Calendar.DATE+ " / " + Calendar.MONTH + " / " + Calendar.YEAR ));
                             ^
  required: int
  found:    String
  reason: argument mismatch; String cannot be converted to int
1 error

The message points to the method cal.get.

For me the latter is more useful. That's why I always have that extra option set.

How to set compiler options?

That depends on how you are compiling. Using javac directly it is as simple as putting the compiler options in javac command line:

javac -encoding UTF-8 -Xlint:deprecation -Xdiags:verbose -cp .;./depJars/* CalendarClass.java

Using an IDE please look at IDE's documentation on how to set extra options to javac.