[jboss-user] [JBoss Seam] - how to catch unhandled exception in the conversation bean

[ellenzhao]

In my view code, the inputText fields are tied to the field setters of managed entities. My conversation bean manages UseCase-related states. 

Let's say there is a UseCase called updateAFood. There is an action button "submit" which calls this method in the conversation bean:


  | private List<Exception> errors = new ArrayList<Exception>();
  | private UseCaseStack;
  | 
  | public void tryFinishUpdateAFood(){
  |   if (there is no exception from entity bean's setter methods) {
  |       this.finishUpdateAFood();
  | } else {
  |   this.errors.addAll(exceptions from entity beans' setter methods);
  | }
  | }
  | 
  | private void finishUpdateAFood(){
  |    Conversation.instance().end();
  |    this.useCases.removeUseCase(UseCase.updateAFood);
  |    this.food.setStatus(CRUDStatus.UPDATED.getSymbolInDB());
  | }
  | 

Here is my utility class UseCaseStack.java

  | public class UseCaseStack {
  |   
  |   private UseCase[] stack;
  |   private int nEntries;
  |   private int size;
  |   
  |   public UseCaseStack() {
  |     size = 10;
  |     stack = new UseCase[size];
  |     nEntries = 0;
  |   }
  |   
  |   public Integer size() {
  |     return nEntries;
  |   }
  |   
  |   public Boolean isEmpty() {
  |     return nEntries == 0;
  |   }
  |   
  |   public void push(UseCase uc) {
  |     if (nEntries == size) {
  |       UseCase[] newstack = new UseCase[2 * size];
  |       for (int i = 0; i < size; i++)
  |         newstack = stack;
  |       stack = newstack;
  |       size *= 2;
  |     }
  |     
  |     this.stack[nEntries++] = uc;
  |   }
  |   
  |   public UseCase pop() {
  |     nEntries--;
  |     UseCase uc = this.stack[nEntries];
  |     this.stack[nEntries] = null;
  |     return uc;
  |   }
  |   
  |   public UseCase peek() {
  |     if (this.nEntries == 0) {
  |       return UseCase.startApp;
  |     } else {
  |       return this.stack[nEntries - 1];
  |     }
  |   }
  |   
  |   public UseCase previous() {
  |     if (this.nEntries <= 1) {
  |       return UseCase.startApp;
  |     } else {
  |       return this.stack[nEntries - 2];
  |     }
  |   }
  |   
  |   public Boolean contains(UseCase uc) {
  |     boolean result = false;
  |     for (int i = nEntries - 1; i >= 0; i--) {
  |       if (this.stack.equals(uc)) {
  |         result = true;
  |         break;
  |       }
  |     }
  |     return result;
  |   }
  |   
  |   public void removeUseCase(UseCase uc) {
  |     for (int i = nEntries - 1; i >= 0; i--) {
  |       if (this.stack.equals(uc)) {
  |         for (int j = i; j < nEntries - 2; j++)
  |           this.stack[j] = this.stack[j + 1];
  |         
  |         this.nEntries--;
  |         break;
  |       }
  |     }
  |   }
  |   
  |   public void removeUpto(UseCase uc) {
  |     while (pop() != uc);
  |   } 
  | }
  | 
  | public enum UseCase { .... }
  | 

Any hint on how to catch the exceptions from the entity bean's setter classes in the conversation bean would be highly appreciated! 


Regards,
Ellen

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