GregorianCalendar getDisplayNames(int, int, Locale) in Java

getDisplayNames(int, int, Locale): This method is available in java.util.GregorianCalendar class of Java.

Syntax:

Map<String, Integer> java.util.Calendar.getDisplayNames(int field, int style, Locale locale)

This method takes three arguments. This method returns a Map containing all names of the calendar field in the given style and locale and their corresponding field values.

Parameters: Three parameters are required for this method.

field: the calendar field for which the display names are returned.

style: the style applied to the string representation; one of SHORT_FORMAT (SHORT), SHORT_STANDALONE, LONG_FORMAT (LONG), LONG_STANDALONE, NARROW_FORMAT, or NARROW_STANDALONE.

locale: the locale for the display names.

Returns: a Map containing all display names in style and locale and their field values, or null if no display names are defined for the field.

Throws:

1. IllegalArgumentException - if field or style is invalid, or if this Calendar is non-lenient and any of the calendar fields have invalid values.

2. NullPointerException - if the locale is null.

Approach 1: When no exception

Java

import java.util.GregorianCalendar;
import java.util.Locale;

public class GregorianCalendargetDisplayNames {
    public static void main(String[] args) {

        GregorianCalendar cal = new GregorianCalendar();

        int field = 0, style = 1;
        Locale locale = Locale.US;

        System.out.println(cal.getDisplayNames(field, 
                                              style, locale));
    }
}

Output:

{AD=1, BC=0}

Approach 2: IllegalArgumentException

Java

import java.util.GregorianCalendar;
import java.util.Locale;

public class GregorianCalendargetDisplayNames {
    public static void main(String[] args) {

        GregorianCalendar cal = new GregorianCalendar();

        int field = -1, style = 1;
        Locale locale = Locale.US;

        System.out.println(cal.getDisplayNames(field,
                                          style, locale));
    }
}

Output:

Exception in thread "main" java.lang.IllegalArgumentException
	at java.base/java.util.Calendar.checkDisplayNameParams(Calendar.java:2252)
	at java.base/java.util.Calendar.getDisplayNames(Calendar.java:2203)
	

Approach 3: NullPointerException 

Java

import java.util.GregorianCalendar;
import java.util.Locale;

public class GregorianCalendargetDisplayNames {
    public static void main(String[] args) {

        GregorianCalendar cal = new GregorianCalendar();

        int field = 0, style = 1;
        Locale locale = null;

        System.out.println(cal.getDisplayNames(field,  
                                          style, locale));
    }
}

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.base/java.util.Calendar.checkDisplayNameParams(Calendar.java:2255)
	at java.base/java.util.Calendar.getDisplayNames(Calendar.java:2203)