Package uk.ac.starlink.table

Class CountCheckRowSequence

java.lang.Object
uk.ac.starlink.table.CountCheckRowSequence
All Implemented Interfaces:
Closeable, AutoCloseable, RowData, RowSequence, uk.ac.starlink.util.Sequence
public class CountCheckRowSequence extends Object implements RowSequence
RowSequence wrapper class that guarantees a given number of rows. The expectation is that the underlying row sequence has the declared row count, but if it has a different number the output of this sequence is forced to the declared value by adding dummy rows or discarding extra rows as required. If such adjustments are required, suitable messages are written through the logging system.
Since:
10 Nov 2022
Author:
Mark Taylor

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    close()
    Indicates that this sequence will not be required any more.
    Object
    getCell(int icol)
    Returns the contents of a cell in the current row.
    Object[]
    getRow()
    Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table.
    static RowSequence
    getSafeRowSequence(RowSequence rseq, int ncol, long nrow)
    Returns a row sequence guaranteed to give the required number of rows.
    boolean
    next()
    Attempts to advance the current row to the next one.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • next

      public boolean next() throws IOException
      Description copied from interface: RowSequence
      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 RowSequence.getCell(int) or RowSequence.getRow() methods.
      Specified by:
      next in interface RowSequence
      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

      public Object getCell(int icol) throws IOException
      Description copied from interface: RowSequence
      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
      Specified by:
      getCell in interface RowSequence
      Parameters:
      icol - column index
      Returns:
      the contents of cell icol in the current row
      Throws:
      IOException - if there is an error reading the data

    • getRow

      public Object[] getRow() throws IOException
      Description copied from interface: RowSequence
      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
      Specified by:
      getRow in interface RowSequence
      Returns:
      an array of the objects in each cell in row irow
      Throws:
      IOException - if there is an error reading the data

    • close

      public void close() throws IOException
      Description copied from interface: RowSequence
      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
      Specified by:
      close in interface RowSequence
      Throws:
      IOException

    • getSafeRowSequence

      public static RowSequence getSafeRowSequence(RowSequence rseq, int ncol, long nrow)
      Returns a row sequence guaranteed to give the required number of rows.
      Parameters:
      rseq - row sequence on which the returned one is based
      ncol - number of columns (required for constructing dummy rows)
      nrow - required number of rows, or -1 for no requirement
      Returns:
      safe row sequence; if nrow<0 the input sequence will be returned