Package org.jfree.report

Interface ReportData

  • All Superinterfaces:
    DataSet
    All Known Implementing Classes:
    EmptyReportData, SQLReportData, TableReportData
    public interface ReportData
extends DataSet
    A report data source is a ordered set of rows. For a report, we assume that the report dataset does not change while the report is processed. Concurrent updates will invalidate the whole precomputed layout. A report dataset will be accessed in a linear fashion. On certain points, the cursor will be reset to the a previously read position, and processing the data will restart from there. It is guaranteed, that the cursor will never be set to a row that is beyond the last row that has been read with 'next()'. If the cursor is out of range, any call to get must return 'null'.
    Author:
    Thomas Morgner

    • Method Detail

      • setCursorPosition

        boolean setCursorPosition​(int cursor)
                   throws DataSourceException
        Moves the cursor back to an already visited position. Calling this method for an row number that has not yet been read using 'next' is undefined, whether that call succeeds is implementation dependent. Calls to position zero (aka BEFORE_FIRST_ROW) will always succeeed (unless there is a physical error, which invalidated the whole report-data object).
        Parameters:
        cursor -
        Returns:
        true, if moving the cursor succeeded, false otherwise.
        Throws:
        DataSourceException

      • isAdvanceable

        boolean isAdvanceable()
               throws DataSourceException
        This operation checks, whether a call to next will be likely to succeed. If there is a next data row, this should return true.
        Returns:
        Throws:
        DataSourceException

      • close

        void close()
    throws DataSourceException
        Closes the datasource. This should be called at the end of each report processing run. Whether this closes the underlying data-source backend depends on the ReportDataFactory. Calling 'close()' on the ReportDataFactory *must* close all report data objects.
        Throws:
        DataSourceException

      • isReadable

        boolean isReadable()
            throws DataSourceException
        Checks, whether this report-data instance is currently readable. A report-data instance cannot be readable if it is positioned before the first row. (The look-ahead system of 'isAdvanceable()' will prevent that the datasource is positioned behind the last row.)
        Returns:
        true, if the datarow is valid, false otherwise.
        Throws:
        DataSourceException