Java17

The pattern matching in Java 17 reduces the boilerplate code by removing the convertion step.

What interesting is the extended scope of pattern created variable. The function whatIsIt1 has a if block, but the airplane and ship variables are extended out of if scope.

import java.time.LocalDate;

public class App {
  public static void main(String[] args) {
      var app = new App();
      var t1 = new Titanic();
      var b1 = new Boing();

      app.whatIsIt(t1);
      app.whatIsIt(b1);
      app.whatIsIt1(t1);
      app.whatIsIt1(b1);
  }

    public void whatIsIt(Object obj) {
      if ( obj instanceof Airplane airplane )
        System.out.println(airplane.name);
      else if (obj instanceof Ship ship ) {
        System.out.println(ship.name);
      }
      else 
        System.out.println("I Don't Know");
    }

    public void whatIsIt1(Object obj) {
      if ( !(obj instanceof Airplane airplane)) {
        if ( !(obj instanceof Ship ship )) {
          System.out.println("I Don't Know");
          return;
        }

        System.out.println(ship.name);
        return; 
      }
      
      System.out.println(airplane.name);
    }

    static class Airplane {
      public String name = "Airplane";
    }

    static class Ship {
      public String name = "Ship";
    }

    static class Boing extends Airplane {

    }

    static class Titanic extends Ship {

    }
}