Java Locale getExtensionKeys() Method

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Description

The Java Locale getExtensionKeys() method returns the set of extension keys associated with this locale, or the empty set if it has no extensions. The returned set is unmodifiable. The keys will all be lower-case.

Declaration

Following is the declaration for java.util.Locale.getExtensionKeys() method

public Set<Character&t; getExtensionKeys()

Parameters

NA

Return Value

This method returns the set of extension keys, or the empty set if this locale has no extensions.

Exception

IllegalArgumentException −

Getting Extension Keys from a Locale Example

The following example shows the usage of Java Locale getExtensionKeys() method. We're creating a locale using forLanguageTag and print the extension keys as specified in the tag and we've created locale using another tag without extension keys and printed an empty set.

package com.tutorialspoint;

import java.util.Locale;

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

      // create a new locale
      Locale locale = Locale.forLanguageTag("und-a-xx-yy-b-zz-ww");

      // print the extension keys
      System.out.println("Extension keys:" + locale.getExtensionKeys());

      locale = Locale.forLanguageTag("und");

      // print the extension keys
      System.out.println("Extension keys:" + locale.getExtensionKeys());
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Extension keys:[a, b]
Extension keys:[]