Question

I’m trying to read from a text files using BufferedReader. I want to skip a line that has “#” and “*” and it works. But it doesn’t work on empty line. I use line.isEmpty() but only the first ouput shows.

My text file looks like this:

# Something something
# Something something


# Staff No. 0

*  0  0  1

1 1 1 1 1 1

*  0  1  1

1 1 1 1 1 1

*  0  2  1

1 1 1 1 1 1

My code:

StringBuilder contents = new StringBuilder();
    try {
      BufferedReader input =  new BufferedReader(new FileReader(folder));
      try {
        String line = null;
        while (( line = input.readLine()) != null){
          if (line.startsWith("#")) {
              input.readLine(); 
          }
          else if (line.startsWith("*")) {
              input.readLine(); 
          }
          else if (line.isEmpty()) { //*this
              input.readLine(); 
          }
          else {
          contents.append(line);
          contents.append(System.getProperty("line.separator"));
          System.out.println(line);
          }
        }
      }
      finally {
        input.close();
      }
    }
    catch (IOException ex){
      ex.printStackTrace();
    }

The output that i want should be like this:

1 1 1 1 1 1
1 1 1 1 1 1
1 1 1 1 1 1

Answer 1

Each call to readline() skips one line if not assigned to a variable, just remove those calls, and since this empties most of the if-else blocks, you can simplify it to:

// to be a bit more efficient
String separator = System.getProperty("line.separator");
while (( line = input.readLine()) != null)
{
    if (!(line.startsWith("#") || 
          line.startsWith("*") ||
          line.isEmpty() )) 
    {
        contents.append(line);
        contents.append(separator);
        System.out.println(line);
    }
}