error java.lang.ArrayIndexOutOfBoundsException

Question

I am having table stored in database i am trying to retrieve all data in it Why i get this error when i tried to retrieve all records in my database? Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 185 at warsh01.selectStmt01.getObjectIDsFromDB(selectStmt01.java:83)

  public static int[] getObjectIDsFromDB (String Dbnum) throws SQLException{
    String selectSQL = "SELECT ID FROM " + Dbnum +.tabName ";
         dbConnection = getDBConnection();
         preparedStatement = dbConnection.prepareStatement(selectSQL);
         ResultSet rs = preparedStatement.executeQuery();  
            rs.last();
            int[] rsIds=new int[rs.getRow()];
            rs.beforeFirst();
            int counter = 1;
            while (rs.next()) {
            rsIds[counter]=rs.getInt(1);
            counter++; // the error is pointing in this line 
            }
             return  rsIds;
      }

in the main method when i tried to run it i got the above exception

 int [] IdsArray ;
    pathIdsArray = getObjectIDsFromDB ("za");
   List<ObjClass>  objItm=new ArrayList<>();
   for (int i = 1; i < IdsArray.length; i++) {
    Item1 = new ObjClass ();
    objectItem1.color=Color.blue;
    objectItem1.LoadFromDB("za", IdsArray[i]);       
    objItm.add(Item1);
    }

Answer 1

I think that you should simply initialise counter to 0 instead of 1 :)

Let's say that your ResultSet has 4 rows . rsIds then is an Array of four int , from rsIds[0] to rsIds[3] .
By initialising counter to 1 and entering 4 times in the while (rs.next()) loop, you:

• never use the rsIds[0] value
• eventually access rsIds[4] (which you can't) in the last iteration.

Hope it helps!

Answer 2

ResultSets have indices starting at 1. But Java arrays have indices starting at 0. You're iterating through the result set with a counter starting at 1, and at each iteration, you initialize rsIds[counter] . You should initialize rsIds[counter - 1] instead (or start the counter at 0).

Note that using a List instead of an array would be much easier:

List<Integer> result = new ArrayList<Integer>();
ResultSet rs = preparedStatement.executeQuery();  
while (rs.next()) {
    result.add(rs.getInt(1));
}

Answer 3

In Java arrays are zero indexed, ie the first element has the index 0 . You are using the counter variable to access the array's positions, but initialize it with 1 .

int counter = 1;
while (rs.next()) {
   rsIds[counter]=rs.getInt(1);
   counter++;
}

Let the row count be eg 5, then you have an array with five "positions" 0,1,2,3,4 . But inside the while loop you are accessing 1,2,3,4, 5 - resulting in an violation of array boundaries.