Checking for a null int value from a Java ResultSet

java null resultset
ian_scho picture ian_scho · May 27, 2010 · Viewed 259.4k times · Source

In Java I'm trying to test for a null value, from a ResultSet, where the column is being cast to a primitive int type. 

int iVal;
ResultSet rs = magicallyAppearingStmt.executeQuery(query);
if (rs.next()) {
  if (rs.getObject("ID_PARENT") != null && !rs.wasNull()) {
    iVal = rs.getInt("ID_PARENT");
  }
}

From the code fragment above, is there a better way to do this, and I assume that the second wasNull() test is redundant?

Educate us, and Thanks

Answer

Richard picture Richard · May 27, 2010

The default for ResultSet.getInt when the field value is NULL is to return 0, which is also the default value for your iVal declaration. In which case your test is completely redundant.

If you actually want to do something different if the field value is NULL, I suggest:

int iVal = 0;
ResultSet rs = magicallyAppearingStmt.executeQuery(query);
if (rs.next()) {
    iVal = rs.getInt("ID_PARENT");
    if (rs.wasNull()) {
        // handle NULL field value
    }
}

(Edited as @martin comments below; the OP code as written would not compile because iVal is not initialised)

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