Locale.forLanguageTag() in Java

forLanguageTag(): This method is available in java.util.Locale class of Java.

Syntax:

Locale java.util.Locale.forLanguageTag(String languageTag)

This method takes one argument of type String as its parameter. This method returns a locale for the specified IETF BCP 47 language tag string.

Parameters: One parameter is required for this method.

languageTag: the language tag.

Returns:The locale that best represents the language tag.

Throws: NullPointerException - if languageTag is null

For Example:

String languageTag = "cel-gaulish"

Locale.forLanguageTag(languageTag) = > It returns  xtg__#x-cel-gaulish.

Approach 1: When String is not null.

Java

import java.util.Locale;

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

        String languageTag = "cel-gaulish";
        System.out.println(Locale.forLanguageTag(languageTag));
    }
}

Output:

xtg__#x-cel-gaulish

Approach 2: When String is null.

Java

import java.util.Locale;

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

        String languageTag = null;
        System.out.println(Locale.forLanguageTag(languageTag));
    }
}

Output:

Exception in thread "main" java.lang.NullPointerException: 
   Cannot invoke "String.length()" 
     because "s" is null
	at java.base/sun.util.locale.LocaleUtils.toLowerString(LocaleUtils.java:89)
	at java.base/sun.util.locale.LanguageTag.parse(LanguageTag.java:192)
	at java.base/java.util.Locale.forLanguageTag(Locale.java:1717)