Java Pattern Matching for instanceof

Java Pattern Matching for instanceof is an improvement of the traditional instanceof operator in Java. It got introduced as a preview feature in Java 14.

Usually, we use the traditional instanceof when we have a reference of superclass type, and we need to check the type of that instance and cast appropriately.

Let’s see first one example with old/traditional instanceof operator:

class Test {

  public static void main(String[] args) {
    Vehicle vehicle = new Car();

    if (vehicle instanceof Car) {
      Car car = (Car) vehicle;
      car.openTrunk();
      // other code ...
    } else if (vehicle instanceof Truck) {
      Truck truck = (Truck) vehicle;
      truck.removeTrailer();
      // other code ...
    }
  }
}

In the above example, we test the vehicle object to see if it is of type Car or a Truck. And based on that, we are casting the object, and calling the appropriate method.

With Java Pattern Matching for instanceof, the same logic can be written as below:

class Test {

  public static void main(String[] args) {
    Vehicle vehicle = new Car();

    if (vehicle instanceof Car car) {
      car.openTrunk();
      // other code ...
    } else if (vehicle instanceof Truck truck) {
      truck.removeTrailer();
      // other code ...
    }
  }
}

We don’t need to cast the object vehicle to a car explicitly. That will be done for us, and the casted object will be placed in the variable car or truck.

That’s it!