Identifier.java

import java.function.*;

class Identifier {
   public static void main (String[] args) {
      int $abc123, $$abc, $a$$b$$c$;  // $ intended for mechanically generated code
      float _abc123, __abc123, _a__b__c_;
      double $;   // Legal, but discouraged
      String __;

      /*
       * The underscore may be used in identifiers formed of two or more
       * characters, but it cannot be used as a one-character identifier
       * due to being a keyword.
       */

      float _;  // now illegal!

      /*
       * Eventually underscore will indicate an unused lambda, method,
       * or catch formal parameter.
      */
      BiFunction<Integer, String, String> biss = (i, _) -> String.valueOf(i);

      int record = 7;
      int true = 3;
      int non=-1, sealed=-2;
      int false = non-sealed;
   }
}