can this code be optimized?

[proff.hacker]

import java.io.*;
public class test {
    public static void main (String[] arg)throws IOException{
        for (int a=2;a<10;a++){
            PrintWriter out = new PrintWriter(new FileWriter(""+a+".txt"));
            for (int b=0;b<10;b++){
                for (int c=0;c<10;c++){
                    for (int d=0;d<10;d++){
                        for (int e=0;e<10;e++){
                            for (int f=0;f<10;f++){
                                for (int g=0;g<10;g++){
                                out.println(""+a+b+c+d+e+f+g);
                                }
                            }
                        }
                    }
                }
            }
        out.close();
        }    
    System.out.println("Done");
    }
} 

I am wondering to know if this code can be optimized to be faster

thanks