Java formatting string of doubles to output file

Question

My code uses BufferedReader to read columns of data in a text file. The text file looks like:

Year.....H2OIN....CO2IN
0.000......0.0..........0.0
1.000......2.0..........6.0
2.000......3.0..........7.0
3.000......4.0..........8.0

My formatting code looks like:

try {
  FileInputStream file = new FileInputStream(inputFile);
  BufferedReader in = new BufferedReader(new InputStreamReader(file));

  f = new Formatter("M:\\TESTPACK\\AL6000803OUT.TXT"); 

  while((line = in.readLine()) != null) {
    if (line.startsWith("    0.000"))
      break;
  }

  while((line = in.readLine()) != null) {
    stream = line.split(parse);
    start = line.substring(6,9);

    if (start.equals("000")) {
      H2OIN = Double.parseDouble(stream[1]);
      CO2IN = Double.parseDouble(stream[2]);

      f.format("%s ", H2OIN);
      f.format("%s ", CO2IN);
    }
  } 
}catch (FileNotFoundException e) {
}catch (IOException e) {
}

f.close();

However, my output file looks like:

2.0 6.0 3.0 7.0 4.0 8.0

While I want it to look like:

2.0 3.0 4.0
6.0 7.0 8.0

I need a suggestion for how to apply formatting to the data strings, not the data itself. Essentially I need to transpose columns of data to rows of data. The duplicate post suggested was not the problem I'm trying to solve.

The problem is not the format here, it's the order in which the numbers are written to the file. You will need to order the numbers before writing the files and make a newline when needed. — Jonathan Drapeau
– Jonathan Drapeau, Commented Aug 20, 2014 at 15:43
I am very new to coding. I understand I may have asked my question incorrectly, but any suggestions to help solve my problem would be great rather than just marking it as a duplicate. — user3657527
– user3657527, Commented Aug 20, 2014 at 16:00
You'll need to include two StringBuffers. One for your H2OIN row and another for your CO2IN row. — Luke Willis
– Luke Willis, Commented Aug 20, 2014 at 16:12

Luke Willis · Accepted Answer · 2014-08-20 19:05:59Z

0

You'll need to include two StringBuffers. One for your H2OIN row and another for your CO2IN row.

Like so:

With your other declarations...

StringBuffer H2OINRow = new StringBuffer();
StringBuffer CO2INRow = new StringBuffer();

In your if (start.equals("000")) block...

// in place of the f.format calls
H2OINRow.Append(H2OIN + " ");
CO2INRow.Append(CO2IN + " ");

After your while loops...

f.format("%s\n", H2OINRow);
f.format("%s\n", CO2INRow);

answered Aug 20, 2014 at 19:05

Luke Willis

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5 Comments

user3657527 Over a year ago

This puts the values from the input table in the correct order, however the output generates a text file with one long line of data.

Luke Willis Over a year ago

Ah, are you using a windows machine? you may need to use "%s\r\n" in your f.format calls. There are OS agnostic solutions, but this ought to work for you.

user3657527 Over a year ago

Indeed I am. I was able to return the lines with a "f.format("%n"), however the data in each string are not separated by spaces; still one long line.

Luke Willis Over a year ago

@user3657527 really? even with the + " " in each of the StringBuffer.Append calls?

user3657527 Over a year ago

That was it! I'd skipped over that. Thanks!

Community · Accepted Answer · 2017-05-23 11:49:31Z

I suggest you gather all the values you want on each line in a different List.

So instead, your while loop would look like :

List<String> h2oValues = new ArrayList<String>();
List<String> c02Values = new ArrayList<String>();
while((line = in.readLine()) != null) {
  stream = line.split(parse);
  start = line.substring(6,9);

  if (start.equals("000")) {
    H2OIN = Double.parseDouble(stream[1]);
    CO2IN = Double.parseDouble(stream[2]);

    h2oValues.add(H2OIN);
    c02Values.add(CO2IN);
  }
}

After that, loop the values of h2oValues to write them in a line and do the same for c02Values

for (String value : h2oValues) {
  f.format("%s ", value);
}
// Add a end of line character... using the system one, you might want to change that
f.format(%n);
for (String value : h2oValues) {
  f.format("%s ", c02Values);
}

For the end line, see this question if you want to change it.

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