Interface RowSequence

All Superinterfaces:
AutoCloseable, Closeable, RowData, uk.ac.starlink.util.Sequence
All Known Subinterfaces:
RowSplittable
All Known Implementing Classes:
AccessRowSequence, CountCheckRowSequence, EmptyRowSequence, IteratorRowSequence, MappingRowSplittable, OnceRowPipe, ProgressRowSplittable, RandomRowSplittable, ReaderRowSequence, SequentialRowSplittable, WrapperRowSequence

public interface RowSequence extends Closeable, RowData, uk.ac.starlink.util.Sequence
Provides sequential access to the data in a table. The data is a sequence of rows which may be processed from the first to the last. A RowSequence iterates over the rows one at a time. It starts off positioned before the first row, so the next method must be invoked before the first row can be accessed.

Typical usage might look like this:

     RowSequence rseq = table.getRowSequence();
     try {
         while ( rseq.next() ) {
             Object[] row = rseq.getRow();
                ...
         }
     }
     finally {
         rseq.close();
     }
 

A RowSequence cannot in general be expected to be used safely from multiple threads.

Author:
Mark Taylor (Starlink)
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    Indicates that this sequence will not be required any more.
    getCell(int icol)
    Returns the contents of a cell in the current row.
    Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table.
    boolean
    Attempts to advance the current row to the next one.
  • Method Details

    • next

      boolean next() throws IOException
      Attempts to advance the current row to the next one. If true is returned the attempt has been successful, and if false is returned there are no more rows in this sequence. Since the initial position of a RowSequence is before the first row, this method must be called before current row data can be accessed using the getCell(int) or getRow() methods.
      Specified by:
      next in interface uk.ac.starlink.util.Sequence
      Returns:
      true iff this sequence has been advanced to the next row
      Throws:
      IOException - if there is some error
    • getCell

      Object getCell(int icol) throws IOException
      Returns the contents of a cell in the current row. The class of the returned object should be the same as, or a subclass of, the class returned by getColumnInfo(icol).getContentClass(). An unchecked exception will be thrown if there is no current row (next has not yet been called).
      Specified by:
      getCell in interface RowData
      Parameters:
      icol - column index
      Returns:
      the contents of cell icol in the current row
      Throws:
      IOException - if there is an error reading the data
      IllegalStateException - if there is no current row (before the start of the table)
    • getRow

      Object[] getRow() throws IOException
      Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table. An unchecked exception will be thrown if there is no current row (next has not yet been called).
      Specified by:
      getRow in interface RowData
      Returns:
      an array of the objects in each cell in row irow
      Throws:
      IOException - if there is an error reading the data
    • close

      void close() throws IOException
      Indicates that this sequence will not be required any more. This should release resources associated with this object. The effect of calling any of the other methods following a close is undefined.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException