Old entry but the error message is still valid so here is what the status -1 means:
public static final int DATABASE_CLOSED -1
public static final int DATABASE_NOTOK -2
public static final int DATABASE_OK 0
Source: http://docs.oracle.com/cd/E18283_01/appdev.112/e13995/constant-values.html#oracle_jdbc_OracleConnection_DATABASE_CLOSED