...
Statement stmt ;
ResultSet rset  ;
...

stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);

QuerySQL = "select sum(len) as inputbyte from monitor  where " ... длинное условие ....";

rset = stmt.executeQuery(QuerySQL);
while (rset.next())
{
           InputByte = rset.getLong("inputbyte");
};
...

 package  com.ksv;

 import  java.sql.Connection;
 import  java.sql.DriverManager;
 import  java.sql.SQLException;
 import  java.sql.Statement;
 import  java.sql.ResultSet;
 import  java.lang.Thread;

 class  statistic  extends  Thread {
	 int  address;
	 long  InputByte,OutputByte;
	String BeginTime, EndTime;
	String QuerySQL = "";
     private   static  String url      = "jdbc:mysql://localhost:3306/netams";
     private   static  String user     = "root";
     private   static  String password = "";
	Connection conn =  null ;
	Statement stmt  =  null ;
	ResultSet rset  =  null ;

	 public   volatile   static   int  countJob =  0 ;

	// constructor
	statistic( int  in_address, String beginTime, String endTime) {
		 this .address = in_address;
		 this .BeginTime = beginTime;
		 this .EndTime = endTime;
	}

	 public   void  run() {
		
		countJob++;
		 try  {
			 Class .forName("com.mysql.jdbc.Driver").newInstance();
		}  catch  (Exception ex) {
			ex.printStackTrace();
		} // catch
		 try  {
			conn = DriverManager.getConnection(url, user, password);
			System.out.println("Connection: " + conn);

			// Get statement object initialized as shown.
			stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
			QuerySQL = "select sum(len) as inputbyte from netams.monitor where dst="
				+ address
				+ " and ..."
				+ " and (time>UNIX_TIMESTAMP(\'" + BeginTime + "\')" 
				+ " and time<UNIX_TIMESTAMP(\'" + EndTime + "\'))";
			
			// Query the database, storing the result in an object of type ResultSet
			rset = stmt.executeQuery(QuerySQL);
			 try  {
			 while  (rset.next()){
				InputByte = rset.getLong("inputbyte");
  			};
			}
			 catch  (NullPointerException en) {
				System.out.println("Address on exception: " + address);
				en.printStackTrace();
				InputByte = 0 ;
				rset.close(); rset =  null ;
			} 			
			 if  (rset!= null ) {rset.close();};
			QuerySQL = "select sum(len) as outputbyte from netams.monitor where src="
				+ address
				+ " and ..."
				+ " and (time>UNIX_TIMESTAMP(\'" + BeginTime +"\')"
				+ " and time<UNIX_TIMESTAMP(\'" + EndTime + "\'))";
			
			rset = stmt.executeQuery(QuerySQL);
			 try  {
			 while  (rset.next()){
			       OutputByte = rset.getLong("outputbyte");
				};
			}
			 catch  (NullPointerException en) {
				System.out.println("Address on exception: " + address);
				en.printStackTrace();
				OutputByte =  0 ;
				rset.close(); rset =  null ;
			} 			
			 if  (rset!= null ) {rset.close();};
          
			System.out.println("Traffic: " + address+" "+InputByte+" "+OutputByte);
			
			conn.close();
			countJob--;
		}
		 catch  (SQLException ex) {
			// handle any errors
			System.out.println("SQLException: " + ex.getMessage());
			System.out.println("SQLState: " + ex.getSQLState());
			System.out.println("VendorError: " + ex.getErrorCode());
		}
	} // run
} // end class definition

 
...
		 try  {
			 while  (rset.next()){
( 57  строка ----->  		InputByte = rset.getLong("inputbyte");
  			};
			}
			 catch  (NullPointerException en) {
				System.out.println("Address on exception: " + address);
				en.printStackTrace();
				InputByte = 0 ;
				rset.close(); rset =  null ;
			} 
...			

    InputByte = rset.getLong( 1 );

     if  (rset ==  null ) {
        System.out.println("rset == null");
    }