java.sql.SQLException: Operation not allowed after ResultSet closed

I faced this problem recently. As a part of closing some resources, I was closing resources in the finally block.

  ResultSet resultSet; // class variable

  ...
  ...
  Statement st = null;
  try {
    st = conn.createStatement();
    resultSet = st.getGeneratedKeys();
  } catch (Exception e) {
    throw e;
  } finally {
    try {
      if (st != null) st.close();
    } catch (SQLException e) {
      throw e;
    }
  }

      

As soon as I did this, I started to get the exception when I tried resultSet.hasNext();

java.sql.SQLException: Operation not allowed after ResultSet closed

My initial guess was I might have executed resultSet.close() somewhere. But it was not the case.

Problem

The actual problem is, ResultSet instance also saves underlying Statement. So, when the underlying Statment is closed (as done in the FINALLY block above), ResultSet is also closed. This causes the problem.

JavaDoc has clearly mentioned this.

When a Statement object is closed, its current ResultSet object, if one exists, is also closed.

Solution

So to fix the problem, you obviously cannot close the Statement instance untill you are done with ResultSet. Once you are done with ResultSet, you can close both ResultSet and Statement.

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