presto-parquet/src/main/java/io/prestosql/parquet/dictionary/DoubleDictionary.java/DoubleDictionary/DoubleDictionary
class DoubleDictionary:    public DoubleDictionary(DictionaryPage dictionaryPage)
            throws IOException
    {
        super(dictionaryPage.getEncoding());
        content = new double[dictionaryPage.getDictionarySize()];
        DoublePlainValuesReader doubleReader = new DoublePlainValuesReader();
        doubleReader.initFromPage(dictionaryPage.getDictionarySize(), toInputStream(dictionaryPage));
        for (int i = 0; i < content.length; i++) {
            content[i] = doubleReader.readDouble();
        }
    }