Java custom exception handling in class

Question

I'm working with netbeans and i created this exception class:

public class VehicleException extends Exception{
    private String matricula;
    private Calendar dataMatricula;
    private ModelVehicle model;

    private int causa;

        public VehicleException(int causa, Object valor) throws Exception {
        this.causa = causa;
        switch (causa) {
            case 1:
                dataMatricula = (Calendar) valor;
                break;
            case 2:
                matricula = (String) valor;
                break;
            case 3:
                model = (ModelVehicle) valor;
                break;

            default:
                throw new Exception("Utilització errònia en construir VehicleException. Causa: " + causa);
        }
    }

         @Override
    public String getMessage() {
        switch (causa) {
            case 1:
                return "dataMatricula erroni: " + dataMatricula + " Ha de contenir valor";
            case 2:
                return "matricula erroni: " + matricula + " Ha de contenir valor";
            case 3:
                return "Model erroni: " + model + " Ha de contenir valor";
            default:
                return "";
        }
    }

And I'm working with this kind of exception in my class "Vehicle" :

public class Vehicle implements Comparable<Vehicle> {

    private String matricula;
    private ModelVehicle model;
    private Calendar dataMatricula;


     public Vehicle(String matricula, ModelVehicle model, Calendar dataMatricula) throws VehicleException {
        setMatricula(matricula);
        setDataMatricula(dataMatricula);
        setModelVehicle(model);


    }


     public String getMatricula(){
         return matricula;
     }

     public ModelVehicle getModelVehicle(){
         return model;
     }
     public Calendar getDataMatricula(){
         return dataMatricula;
     }


      public final void setMatricula(String matricula) throws VehicleException {
        if (matricula == null || matricula.compareTo("") == 0) {
            throw new VehicleException(2,matricula);
        }
        this.matricula = matricula;
    }

      public void setModelVehicle(ModelVehicle model) throws VehicleException{
          if(model == null){
             throw new VehicleException(3,model);
          }
          else {
              this.model = model;
          }
      }

      public void setDataMatricula(Calendar c) throws VehicleException{
          if(c == null){
             throw new VehicleException(1,c);
          }
          this.dataMatricula = c;
      }

The problem cones when i try to compile,in the setter methods i get this message :

error: unreported exception Exception; must be caught or declared to be thrown throw new VehicleException(2,matricula); C:\Users\Ivan\Desktop\Examen isidrer\M03-uf5\Exmaenm03uf5\src\info\infomila\Vehicle.java:55: error: unreported exception Exception; must be caught or declared to be thrown throw new VehicleException(3,model); C:\Users\Ivan\Desktop\Examen isidrer\M03-uf5\Exmaenm03uf5\src\info\infomila\Vehicle.java:64: error: unreported exception Exception; must be caught or declared to be thrown throw new VehicleException(1,c);

I don't quite undestand why this is happening, crearly the setter methods have a "throws VehicleException".

castletheperson · Accepted Answer · 2017-03-26 22:11:17Z

5

The constructor for VehicleException can throw an exception itself:

public VehicleException(int causa, Object valor) throws Exception {
                                                 ^^^^^^^^^^^^^^^^

This means your calling scope would need to handle/rethrow that exception from the constructor, or you could choose to suppress the exception rather than throwing it.

default:
    super.addSuppressed(new Exception("Utilització errònia en construir VehicleException. Causa: " + causa));

edited Mar 26, 2017 at 22:11

answered Mar 26, 2017 at 22:05

castletheperson

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3 Comments

Izruo Over a year ago

From the message passed to the Exception constructor i'd usually tend to throw a RuntimeException here.

castletheperson Over a year ago

@Izruo If they throw a RuntimeException, then the VehicleException would never be seen, so this allows both exceptions to appear in the error log.

Izruo Over a year ago

My point is that an Exception is normally suppressed when it is caused due to some other Exception being thrown. This one here will be thrown when a programmer uses a wrong constant in his code (which in this case is throwing the Exception). But when it comes to logging, you've got a point here.

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