Unexpected behavior when creating Objects in a Vector
I have a situation where Objects in a Vector appear to be getting corrupted. The context is this: I obtain a ResultSet from a database, create a Vector of Strings for each row, and a Vector of these row vectors for the entire ResultSet. This is passed to a method where a POJO is created for each row. This method returns a Vector of these POJOs. In the Object constructor, a String array of initial values is created and also values are assigned to individual variables. Here is a snippet with the Object constructor
publicclass RefAuthorItem{
privatefinal String refKey;
private String authorKey, firstName, lastName, itemKey;
privateint authorPosition;
privateboolean isDeleted, isNew;
// Keep a copy of the original values
privatefinal String[] oldValues;
/**
* The constructor for the data object item.
*
* @param dataValsa String array of the data values
* @param isNewValboolean true if this is a new item, false if it is
* an existing item
*/
public RefAuthorItem(final String[] dataVals,finalboolean isNewVal){
oldValues = dataVals;
authorKey = dataVals[RefQueryBuilder.AUTH_NUM];
firstName = dataVals[RefQueryBuilder.AUTH_FIRST_NAME];
itemKey = dataVals[RefQueryBuilder.AUTH_PKEY];
lastName = dataVals[RefQueryBuilder.AUTH_LAST_NAME];
refKey = dataVals[RefQueryBuilder.AUTH_REF_FKEY];
isNew = isNewVal;
isDeleted =false;
// the author position integer value is used to sort the display
authorPosition =
Integer.parseInt(dataVals[RefQueryBuilder.AUTH_POS]);
}
It seems the oldValues[] values should be identical to the corresponding individual variable values. When the following code is used to create the objects, they are not.
finalboolean isNew = isNewVal;
Vector<RefAuthorItem> returnSet =new Vector<RefAuthorItem>();
final String queryString = QueryBuilder
.getRefQuery(keyString, tableName);
Vector<Vector> dataSet = QueryDB.getResultSet(queryString);
int columnTot = dataSet.firstElement().size();
String[] itemVals =new String[columnTot];
for (Iterator iter = dataSet.iterator(); iter.hasNext();){
Vector element = (Vector) iter.next();
for (int i = 0; i < columnTot; i++){
itemVals[i] = (String) element.get(i);
}
RefAuthorItem item =new RefAuthorItem(itemVals, isNew);
returnSet.add(item);
}
What happens is this. I returned four rows from the database and the oldValues[] array for each of the four corresponding objects contains the data from the fourth row. However, when I retrieve the corresponding individual values (e.g., authorLastName) from the Object, it is correct. I checked the object values (oldValues versus individual values retrieved via getters) right after the object is created (the line: RefAuthorItem item = new RefAuthorItem(itemVals, isNew);) and get the correct results. Also, results are correct when the itemVals constructor is moved within the loop, as below
int columnTot = dataSet.firstElement().size();
for (Iterator iter = dataSet.iterator(); iter.hasNext();){
Vector element = (Vector) iter.next();
String[] itemVals =new String[columnTot];
for (int i = 0; i < columnTot; i++){
itemVals[i] = (String) element.get(i);
}
RefAuthorItem item =new RefAuthorItem(itemVals, isNew);
returnSet.add(item);
}
There is a problem here. Am I missing a subtle Java issue with instantiating the String array within the loop? Or is there a problem with Vectors? Thanks!
