I try to set the encoding of my editor to UTF-16. (Java String store the data in UTF-16 internally, right?)

And I type the following code

package helloworld;

/**
 *
 * @author yan-cheng.cheok
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        System.out.println("???");
        System.out.println("\u6587\u4EF6\u79CD\u7C7B");
    }

}

However, the output is not what I expected :

????
?????

I try to change the editor encoding format to UTF-8, it works this time!

???
????

May I know why I need to change the editor encoding format to UTF-8 but not UTF-16? Isn't Java String store the data in UTF-16 internally?