Clean up after exception thrown in constructor

From:
Philipp <sicsicsic@freesurf.ch>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 15 Apr 2008 15:38:38 +0200
Message-ID:
<1208266720_3093@sicinfo3.epfl.ch>
Hello

I have a class hierarchy where the constructor of a child class ("Ford")
can throw an exception, while the constructor of the parent class
("Car") has some side-effects.
If construction fails due to the Exception on the child class being
thrown, the side-effect of the parent constructor cannot be cleaned up.

What would be a better approach to this problem, so that if construction
fails for whatever reason, the system is left in a pristine state?

Thanks for your advice
Phil

Example SSCCE:
package exceptionInCtor;

import java.util.ArrayList;
import java.util.List;

public class Car {
   private static List<String> nameList = new ArrayList<String>();
   private String name;

   public Car(String name){
     nameList.add(name); // name is added to list as side-effect
     this.name = name;
   }

   public void remove(){ // called when car is no longer used
     nameList.remove(name);
   }

   public static class Ford extends Car{
     public Ford(String name, int wheels){
       super(name);
       if(wheels > 4){
         throw new IllegalArgumentException("Too many wheels");
       }
     }
   }

   public static void main(String[] args) {
     Car c = null;
     try{
       c = new Ford("myFord", 5);
     } catch (Exception e) {
       // cannot call c.remove() here!
       e.printStackTrace();
     }

     System.out.println(c); // prints null
     System.out.println(nameList); // prints [myFord], should be empty
   }
}

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