关于BufferedReader的读取效率问题

            InputStreamReader isr = new InputStreamReader(connection.getInputStream(), "UTF-8");
            in = new BufferedReader(isr);
            String line; 
            while ((line = in.readLine()) != null) {
                result += line;
            }

            inputStream = connection.getInputStream();
            isr = new InputStreamReader(inputStream, "UTF-8");
            in = new BufferedReader(isr);
            CharBuffer bos = CharBuffer.allocate(20480);
            StringBuilder builder = new StringBuilder();
            while (in.read(bos) != -1) {
                bos.flip();
                builder.append(bos.toString());
            }

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStreamReader;  
public class Main 
{ 
    public static  void main(String[]args) 
    {
        BufferedReader buf=null;
        buf=new BufferedReader(new InputStreamReader(System.in));
        String str=null; 
        try { 
            int a= Integer.parseInt(buf.readLine()); 
            
            double b=Double.parseDouble(buf.readLine());
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println();
    }
}