Converting Object[] array to List in java

Question

on a primefaces 3.5 form I created with a datatable the rowKey value is not being returned as a List, therefore I am getting the following error:

JBWEB000309: type JBWEB000066: Exception report

JBWEB000068: message For input string: "foreignPartyId"

JBWEB000069: description JBWEB000145: The server encountered an internal error that prevented it from fulfilling this request.

JBWEB000070: exception

javax.servlet.ServletException: For input string: "foreignPartyId"
    javax.faces.webapp.FacesServlet.service(FacesServlet.java:606)
JBWEB000071: root cause

java.lang.NumberFormatException: For input string: "foreignPartyId"
    java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    java.lang.Integer.parseInt(Integer.java:492)
    java.lang.Integer.parseInt(Integer.java:527)
    javax.el.ListELResolver.toInteger(ListELResolver.java:407)
    javax.el.ListELResolver.getValue(ListELResolver.java:199)
...

I know the reason is because I am trying to populate the datatable with values from an Object[] array, rather than a List. The Object[] array is actually values from getResultList() using the createNativeQuery method to query an Oracle database.

My question is: How do I convert the values in the Object[] array into a List so that the datatable is populated?

I have tried using the Arrays.toList() method, and then iterating through that adding the values to a list, but I understand that that simply returns a fixed size list of the backed array. It does not return a List of values.

Any help would be greatly appreciated. My apologies if I have not provided enough detail. Thank you.

Solution 1

Try with ArrayList:

ArrayList<Object> list = new ArrayList(Arrays.asList(yourArray));

and then add whatever element you want to the list using

list.add(newItem)

Solution 2

The getResultList method do return a List<Object[]> if you are for example querying multiple entities and the result cannot be mapped automatically onto an existing entity class.

To avoid this you may consider a constructor expression in your JPA query like this:

Query query = getEntityManager()
  .createQuery("SELECT NEW my.Foo(a.id, b.somethingelse) FROM --- ");

The getResultList() method now will return a List<Foo> and you do not run into the problem that you have mentioned.