Method Now Abstract

The abstract modifier is added to the declaration of a library method and its body is removed.

Example

The abstract class Vehicle removes the static modifier and adds the abstract modifier to the move method. Afterwards, the method’s body is removed.

public abstract class Vehicle {
-  public static void move() {
-    System.out.println("The vehicle is moving.");
-  }
+  public abstract move();
}

Broken Uses

Hereafter, we list the broken uses that are currently detected by Maracas.

• 1. Non-abstract types extending/implementing the enclosing type of the now-abstract method
• 2. Invocations in subtypes of the now-abstract method

1. Non-abstract types extending/implementing the enclosing type of the now-abstract method

(Unless the now-abstract method is already implemented somewhere in the hierarchy)

Example

The LanVehicle class—declared in the in a client project—extends the Vehicle class form the library. Then, a broken use is reported pointing to the class declaration given that no implementation for the now-abstract method move has been provided.

public class LandVehicle extends Vehicle {

}

2. Invocations in subtypes of the now-abstract method

Example

The method printMove—defined in the LandVehicle class in a client project—invokes the now-abstract method move from the Vehicle class. Then, a broken use is reported pointing to the method invocation expression.

public class LandVehicle extends Vehicle {

  public static void printMove() {
    // Broken use reported here
    Vehicle.move();
  }

}