Package org.apache.poi.xssf.model

Class SharedStringsTable

  • All Implemented Interfaces:
    Closeable, AutoCloseable, SharedStrings
    public class SharedStringsTable
extends POIXMLDocumentPart
implements SharedStrings, Closeable
    Table of strings shared across all sheets in a workbook.

    A workbook may contain thousands of cells containing string (non-numeric) data. Furthermore this data is very likely to be repeated across many rows or columns. The goal of implementing a single string table that is shared across the workbook is to improve performance in opening and saving the file by only reading and writing the repetitive information once.

    Consider for example a workbook summarizing information for cities within various countries. There may be a column for the name of the country, a column for the name of each city in that country, and a column containing the data for each city. In this case the country name is repetitive, being duplicated in many cells. In many cases the repetition is extensive, and a tremendous savings is realized by making use of a shared string table when saving the workbook. When displaying text in the spreadsheet, the cell table will just contain an index into the string table as the value of a cell, instead of the full string.

    The shared string table contains all the necessary information for displaying the string: the text, formatting properties, and phonetic properties (for East Asian languages).

    • Field Detail

      • count

        protected int count
        An integer representing the total count of strings in the workbook. This count does not include any numbers, it counts only the total of text strings in the workbook.

      • uniqueCount

        protected int uniqueCount
        An integer representing the total count of unique strings in the Shared String Table. A string is unique even if it is a copy of another string, but has different formatting applied at the character level.

    • Constructor Detail

      • SharedStringsTable

        public SharedStringsTable()

    • Method Detail

      • readFrom

        public void readFrom​(InputStream is)
              throws IOException
        Read this shared strings table from an XML file.
        Parameters:
        is - The input stream containing the XML document.
        Throws:
        IOException - if an error occurs while reading.

      • xmlText

        protected String xmlText​(org.openxmlformats.schemas.spreadsheetml.x2006.main.CTRst st)

      • getItemAt

        public RichTextString getItemAt​(int idx)
        Return a string item by index
        Specified by:
        getItemAt in interface SharedStrings
        Parameters:
        idx - index of item to return.
        Returns:
        the item at the specified position in this Shared String table.

      • getCount

        public int getCount()
        Return an integer representing the total count of strings in the workbook. This count does not include any numbers, it counts only the total of text strings in the workbook.
        Specified by:
        getCount in interface SharedStrings
        Returns:
        the total count of strings in the workbook

      • getUniqueCount

        public int getUniqueCount()
        Returns an integer representing the total count of unique strings in the Shared String Table. A string is unique even if it is a copy of another string, but has different formatting applied at the character level.
        Specified by:
        getUniqueCount in interface SharedStrings
        Returns:
        the total count of unique strings in the workbook

      • addSharedStringItem

        public int addSharedStringItem​(RichTextString string)
        Add an entry to this Shared String table (a new value is appended to the end).

        If the Shared String table already contains this string entry, its index is returned. Otherwise a new entry is added.

        Parameters:
        string - the entry to add
        Returns:
        index the index of added entry
        Since:
        POI 4.0.0

      • getSharedStringItems

        public List<RichTextString> getSharedStringItems()
        Provide access to the strings in the SharedStringsTable
        Returns:
        list of shared string instances

      • writeTo

        public void writeTo​(OutputStream out)
             throws IOException
        Write this table out as XML.
        Parameters:
        out - The stream to write to.
        Throws:
        IOException - if an error occurs while writing.

      • commit

        protected void commit()
               throws IOException
        Description copied from class: POIXMLDocumentPart
        Save the content in the underlying package part. Default implementation is empty meaning that the package part is left unmodified.

        Sub-classes should override and add logic to marshal the "model" into Ooxml4J.

        For example, the code saving a generic XML entry may look as follows: 

         protected void commit() throws IOException {
   PackagePart part = getPackagePart();
   try (OutputStream out = part.getOutputStream()) {
     XmlObject bean = getXmlBean(); //the "model" which holds changes in memory
     bean.save(out, DEFAULT_XML_OPTIONS);
   }
 }
        Overrides:
        commit in class POIXMLDocumentPart
        Throws:
        IOException - a subclass may throw an IOException if the changes can't be committed

      • close

        public void close()
           throws IOException
        Close any open resources, like temp files. This method is called by XSSFWorkbook#close().

        This implementation is empty but subclasses may need to implement some logic.

        Specified by:
        close in interface AutoCloseable
        Specified by:
        close in interface Closeable
        Throws:
        IOException - if an error occurs while closing.
        Since:
        4.0.0