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From Muthusree <muthusree.securen...@gmail.com>
Subject New to Lucene.Net
Date Fri, 29 Jun 2007 09:15:12 GMT
Hi frnds,
           I am trying to create a search engine using Lucene.Net in vb.net.
Indexing works well.. but i think there is some mistake with either the
parser or the searcher. I get the following error while running in the line
A i have mentioned below.

An unhandled exception of type 'System.NullReferenceException' occurred in
mysrch.exe

Additional information: Object reference not set to an instance of an
object.

Here is my code. Pls tell me wat's to be done ..

Imports Lucene.Net.Analysis
Imports Lucene.Net.Documents
Imports Lucene.Net.Documents.Field
Imports Lucene.Net.Analysis.Standard
Imports Lucene.Net.Index
Imports Lucene.Net.search
Imports Lucene.Net.QueryParsers
Imports Lucene.Net.Util.StringHelper
Imports System.IO
Imports System.IO.FileStream

Public Class indexer
    Dim filedir As New DirectoryInfo("E:\lucene\test\Resumes\")
    Dim indexdir As New String("C:\index\")
    Dim anlr As New Lucene.Net.Analysis.Standard.StandardAnalyzer()
    Dim writer As IndexWriter
    Dim pattern As String
    Dim docrootdirectory As String
    Dim filepath, relativepath As String
    Dim srchr As IndexSearcher
    Dim q As Lucene.Net.Search.Query

    Private Sub indexer_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
        Dim writer As New IndexWriter(indexdir, anlr, True)
        writer.SetUseCompoundFile(True)
        '  AddDirectory(filedir, "*.doc")
        newindexer()
    End Sub

Public Sub newindexer()
        Dim writer As New IndexWriter(indexdir, anlr, False)
        Dim rawtext As String
        Dim txtfiles() As FileInfo = filedir.GetFiles("*.*")
        Dim i As Integer
        For i = 0 To txtfiles.Length - 1
            Dim txtfilepath As String = txtfiles(i).FullName
            Dim txtfilename As String = txtfiles(i).ToString
            If txtfiles(i).Extension = ".txt" Then
                ' Form1.Lblindex.Text = "Files " + txtfilepath + " has been
indexed"
                Form1.Lblindex.Text = "Files has been indexed"
                Dim textReader As New StreamReader(txtfilepath,
System.Text.Encoding.Default)
                rawtext = textReader.ReadToEnd
                Dim document As New Document()
                               document.Add(New Field("text", rawtext,
Store.YES, Index.TOKENIZED))
                document.Add(New Field("path", txtfilepath, Store.YES,
Index.UN_TOKENIZED))
                document.Add(New Field("filename", txtfilename, Store.YES,
Index.UN_TOKENIZED))
                writer.AddDocument(document)
            End If
        Next i
        writer.Close()
    End Sub ' Index

    Public Sub srch()
        Try
            Dim srchr As Searcher
            srchr = New IndexSearcher("C:\index\")
        Catch ex As IOException
            MessageBox.Show(("The index doesn't exist or is damaged. Please
rebuild the index." + ControlChars.Cr + ControlChars.Lf + ControlChars.Cr +
ControlChars.Lf + "Details:" + ControlChars.Cr + ControlChars.Lf +
ex.Message))
            Return
        End Try
        'Dim query As TermQuery
        'query = QueryParser.Parse(q, "text", New StandardAnalyzer())
        ''  Dim querys As Query = QueryParser.Parse("index", "text", New
StandardAnalyzer())
        Try
            Dim parser As New QueryParser("text", anlr)
            q = parser.Parse("the")
        Catch ex As Lucene.Net.QueryParsers.ParseException
            MessageBox.Show(ex.ToString)
        End Try
        ' Dim query As Query = QueryParser.Parse(Text, "text", New
StandardAnalyzer())
        If q Is Nothing Then
            MsgBox("Query is null")
        Else
            Dim h As Hits = srchr.Search(q)
--------------------------------------------------------------------A
            Dim i As Integer
            For i = 0 To (h.Length()) - 1
                Dim doc As Document = h.Doc(i)
                Dim filename As String = doc.Get("filename")
                Dim p As String = doc.Get("path")
                Dim folder As String = Path.GetDirectoryName(p)
                Dim di As New DirectoryInfo(folder)
                Form1.rtb.AppendText(vbCrLf & filename & ",")
            Next i
            srchr.Close()
            Form1.rtb.AppendText(vbCrLf & "NUMBER OF MATCHING CONTACTS: " +
h.Length())
            For i = 0 To (h.Length()) - 1
                Form1.rtb.AppendText("NAME: " + h.Doc(i).Get("filename"))
            Next i
        End If
    End Sub 'search

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