Very slow painting while reading and writing doubles into file

Question

for 15MB length file i = 7662080
for 50MB length file i = 12414368
Part of Code for writing into file follows like this:
try{
fos = new FileOutputStream("Angel.txt");
File f = new File("Angel.txt");
     if(f.length() >=4)
     f.delete();
fos = new FileOutputStream("Angel.txt");     
dos = new DataOutputStream(new BufferedOutputStream(fos,1000000));
int x=0;
double y_last, y_new;
for(int j=0 ;j<i ;j++)
if(some condition)
y_new = ....;
try{
//previously in vectors
y_last = y_new;
vect.add(new Line2D.Double(x, y_last, x, y_new)_;
dos.writeDouble(y_new);
     }catch(Exception e){System.out.println(e);}
dos.close();
fos.close();
x++;
}catch(Exception excp){System.out.println(excp);}
part of code for reading from file follows like this:
public void paint(Graphics g)
try{
     double y1, y2 =0;               
     Line2D.Double doub;
     raf = new RandomAccessFile("Angel.txt","r");
     dis = new DataInputStream(new BufferedInputStream(new FileInputStream(raf.getFD(),1000000)));
     raf.seek((rect.x*8));
     for (int i = 0/any value; (i < value as per choice); i++)
          g2.setStroke(new BasicStroke(0)); //2
          y1 = y2;
     y2 =dis.readDouble();
          doub=new Line2D.Double(i,y1,i,y2);
          g2.draw(doub);
dis.close();
     raf.close();
}catch(Exception excp){System.out.println(excp);}
I tried using Object Streams but NotSerializable Exception is thrown as Line2D.Double objects
are not serialized.
Any idea to make reading and writing into file specially from MB files faster is appreciated.

Answer 1

Why are you reading in the file in the paint method ?
Create your data once before painting.
I think you should explain what is your goal and what behavior you want.
Denis