| org.jfree.report.ReportData
All known Subclasses: org.jfree.report.EmptyReportData, org.jfree.report.modules.data.sql.SQLReportData, org.jfree.report.TableReportData,
| ReportData | | public interface ReportData extends DataSet(Code) | | 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 Summary | |
| public void | close()
Closes the datasource. | | public int | getCursorPosition()
| | public boolean | isAdvanceable()
This operation checks, whether a call to next will be likely to succeed. | | public boolean | isReadable()
Checks, whether this report-data instance is currently readable. | | public boolean | next()
| | public boolean | setCursorPosition(int cursor)
Moves the cursor back to an already visited position. |
| BEFORE_FIRST_ROW | | final public static int BEFORE_FIRST_ROW(Code) | | |
| close | | public void close() throws DataSourceException(Code) | | 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 - |
| isAdvanceable | | public boolean isAdvanceable() throws DataSourceException(Code) | | This operation checks, whether a call to next will be likely to succeed.
If there is a next data row, this should return true.
throws:
DataSourceException - |
| isReadable | | public boolean isReadable() throws DataSourceException(Code) | | 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.)
true, if the datarow is valid, false otherwise.
throws:
DataSourceException - |
| setCursorPosition | | public boolean setCursorPosition(int cursor) throws DataSourceException(Code) | | 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 - true, if moving the cursor succeeded, false otherwise.
throws:
DataSourceException - |
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