public  void testDocCount() 
{
        Directory dir = new RAMDirectory();
        IndexWriter writer = null;
        IndexReader reader = null;
        int i;
        try {
            writer  = new IndexWriter(dir, new WhitespaceAnalyzer(), true);
            // add 100 documents
            for (i = 0; i <  100; i++) {
                addDoc(writer);
            }
            assertEquals(100, writer.docCount());
            writer.close();
            // delete 40 documents
            reader = IndexReader.open(dir);
            for (i = 0; i <  40; i++) {
                reader.delete(i);
            }
            reader.close();
            // test doc count before segments are merged/index is optimized
            writer = new IndexWriter(dir, new WhitespaceAnalyzer(), false);
            assertEquals(100, writer.docCount());
            writer.close();
            reader = IndexReader.open(dir);
            assertEquals(100, reader.maxDoc());
            assertEquals(60, reader.numDocs());
            reader.close();
            // optimize the index and check that the new doc count is correct
            writer = new IndexWriter(dir, new WhitespaceAnalyzer(), false);
            writer.optimize();
            assertEquals(60, writer.docCount());
            writer.close();
            // check that the index reader gives the same numbers.
            reader = IndexReader.open(dir);
            assertEquals(60, reader.maxDoc());
            assertEquals(60, reader.numDocs());
            reader.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
}