Package uk.ac.starlink.table

Class ReaderRowSequence

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, RowData, RowSequence, uk.ac.starlink.util.Sequence
    public abstract class ReaderRowSequence
extends java.lang.Object
implements RowSequence
    Partial implementation of RowSequence suitable for subclassing by classes which can read a row at a time and don't know when the row stream will come to an end. Concrete subclasses have to implement the readRow() method. They may also want to override close().
    Author:
    Mark Taylor (Starlink)

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      void close()
      The ReaderRowSequence implementation does nothing.
      java.lang.Object getCell​(int icol)
      Returns the contents of a cell in the current row.
      java.lang.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.
      boolean next()
      Attempts to advance the current row to the next one.
      protected abstract java.lang.Object[] readRow()
      Acquires the next row of objects from the input stream.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • ReaderRowSequence

        public ReaderRowSequence()

    • Method Detail

      • readRow

        protected abstract java.lang.Object[] readRow()
                                       throws java.io.IOException
        Acquires the next row of objects from the input stream. When there are no more rows to read this method must return null; note it should not throw an exception to indicate this fact. Otherwise it must return an array of objects representing the row content for the next row.
        Returns:
        the next row, or null if there are no more
        Throws:
        java.io.IOException - if there is trouble reading the data

      • next

        public boolean next()
             throws java.io.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:
        java.io.IOException - if there is some error

      • getCell

        public java.lang.Object getCell​(int icol)
        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

      • getRow

        public java.lang.Object[] getRow()
        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

      • close

        public void close()
           throws java.io.IOException
        The ReaderRowSequence implementation does nothing.
        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Specified by:
        close in interface RowSequence
        Throws:
        java.io.IOException