Question

I have the following code:

public static void main(String[] args) throws Exception {
    String s = "";
    StringBuilder sb = new StringBuilder();
    File file = new File("C:\\New\\r.txt");

    BufferedReader in = new BufferedReader(new FileReader(file));
    while(in.readLine() != null) {      
        sb.append(in.readLine());
    }

    System.out.println(sb);
    s = sb.toString();
    byte[] b = s.getBytes();

   for(int i = 0; i < b.length; i++) {
       if(b[i] == 1){ b[i]=0; }
       if(b[i] == 0){ b[i]=1; }
   }

   FileOutputStream fos = new FileOutputStream(file);
   DataOutputStream dos = new DataOutputStream(fos);
   dos.write(b);
   in.close();
   fos.close();
   dos.close();
}

I get a return of null when I run this program. Maybe I must elevate the program? Help would be appreciated.

Answer 1

Change:

 while(in.readLine()!=null)

to:

 while((s = in.readLine())!=null)

and then:

sb.append(s);

When you call in your code to in.readLine() twice – you’re reading two lines but printing only the second in each iteration.