Question

I got a method that throw an exception if I try to insert an existing object in DB.

 public void addInDB() throws Exception {
    if (isInBase()){
          throw new Exception ("[ReqFamily->addInDB] requirment already in base");
    }
    int idParent = m_parent.getIdBdd();

    idBdd = pSQLRequirement.add(name, description, 0, idParent,   
    ReqPlugin.getProjectRef().getIdBdd(), 100);
}

So when the exception is thrown I wanna catch it and display an error messsage in my managed bean.

PS: In my managed bean I just call the method :

void addReq(Requirement req){
    try {
        ReqFamily pReqParent = (ReqFamily) selectedNode.getData();
        req.setParent(pReqParent);
        req.addInDB();//here i want to catch it 


        DefaultTreeNode newReqNode = new DefaultTreeNode(req,selectedNode);
        if (pReqParent!=null){
            pReqParent.addRequirement(req);
        }

    } catch (Exception ex){

        ex.printStackTrace();
    }
}

Answer 1

Its bad practice to catch or throw Exception. If any code you use throws a checked exception then just catch that specific exception, and try to minimize the size of your try-catch blocks.

class MyException extends Exception {
    ...

public void addInDB() throws MyException {
    if (isInBase()){
        throw new MyException ("[ReqFamily->addInDB] requirment already in base");
    }
    ...

void addReq(Requirement req){
    ReqFamily pReqParent = (ReqFamily) selectedNode.getData();
    req.setParent(pReqParent);

    try {
        req.addInDB();
    } catch (MyException ex){
        ex.printStackTrace();
    }

    DefaultTreeNode newReqNode = new DefaultTreeNode(req,selectedNode);
    if (pReqParent!=null){
        pReqParent.addRequirement(req);
    }
}