Locale.Builder setLanguageTag() method in Java with Examples

The setLanguageTag(String) method of java.util.Locale.Builder class in Java is used to reset this Locale.Builder to the specified IETF BCP 47 language tag. It means that this method will reset the current state of Locale.Builder instance to match the provided language tag and return it.

Syntax:

public Locale.Builder setLanguageTag(String languageTag)

Parameter: This method accepts the languageTag as the parameter which is the String that is to be set to this Locale.Builder instance.

Return Value: This method returns an Locale.Builder instance which is the state of this Locale.Builder set to the specified language tag.

Exception: This method throws following Exceptions:

• IllformedLocaleException: if the specified languageTag has any ill formed fields

Program 1:

// Java program to demonstrate
// the above method

import java.util.*;
import java.util.Locale.*;

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

        // Creating a new Locale.Builder
        Locale.Builder localeBuilder
            = new Builder();

        // Displaying Locale.Builder
        System.out.println("LocaleBuilder: "
                           + localeBuilder);

        // setting the languageTag
        // of Locale.Builder
        String languageTag = "FRENCH";
        System.out.println("Setting the language: "
                           + languageTag);

        localeBuilder
            = localeBuilder
                  .setLanguageTag(languageTag);

        // Displaying Locale.Builder
        System.out.println("Updated LocaleBuilder: "
                           + localeBuilder);
    }
}

Output:

LocaleBuilder: java.util.Locale$Builder@232204a1
Setting the language: FRENCH
Updated LocaleBuilder: java.util.Locale$Builder@232204a1

Program 2:

// Java program to demonstrate
// the above method

import java.util.*;
import java.util.Locale.*;

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

        // Creating a new Locale.Builder
        Locale.Builder localeBuilder
            = new Builder();

        // Displaying Locale.Builder
        System.out.println("LocaleBuilder: "
                           + localeBuilder);

        // setting the languageTag
        // of Locale.Builder
        String languageTag = "asdasf@!vsd#";
        System.out.println("Setting the languageTag: "
                           + languageTag);

        try {
            localeBuilder
                = localeBuilder
                      .setLanguageTag(languageTag);

            // Displaying Locale.Builder
            System.out.println("Updated LocaleBuilder: "
                               + localeBuilder);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

LocaleBuilder: java.util.Locale$Builder@232204a1
Setting the languageTag: asdasf@!vsd#
java.util.IllformedLocaleException: Invalid subtag: asdasf@!vsd# [at index 0]

Reference: https://docs.oracle.com/javase/9/docs/api/java/util/Locale.Builder.html#setLanguageTag-java.lang.String-