Java Database Connectivity (JDBC)

hi.
I got error when use getBinaryStream(), Here is My code.

please tell me how to solve this probleam.
Thanks in advance.

Insert Blob to Datase Code
---
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
conn = DriverManager.getConnection("jdbc:oracle:oci8:@XBRL","mgtk","mgtk");
String Quary = "update COMPANY_DETAIL set COMPNAY_LOGO = ? where COMPANY_ID = " +companyId.toString();
System.out.println(Quary);
java.io.ByteArrayInputStream fin = new ByteArrayInputStream(detailPkt.getLogo());
pstmt = conn.prepareStatement(Quary);
pstmt.setBinaryStream(1,fin,detailPkt.getLogo().length);
int rows = pstmt.executeUpdate();
conn.commit();
pstmt.close();

retreive Blob Data Code
-----------------
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
conn = DriverManager.getConnection("jdbc:oracle:oci8:@XBRL", "mgtk","mgtk");
String Quary =
"select COMPNAY_LOGO from COMPANY_DETAIL where COMPANY_ID = " + companyPk.toString();

stmt = conn.createStatement();
resultSet = stmt.executeQuery(Quary);
if (resultSet.next()) {
logo = resultSet.getBlob(1);
}
else {
System.out.println("Not found");
return null;
}

InputStream in = logo.getBinaryStream(); <=== I get Error message from this line
int length = (int) logo.length();

byte[] buffer = new byte[length];
in.read(buffer);
in.close();
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Error Message:
java.lang.NullPointerException