How to fix my printWriter and get a full output on text file

Question

    import java.io.File;
    import java.io.PrintWriter;

    public class Hw6Problem004 {

        public static void main(String[] args) throws Exception {
            {



                double j = 120;
                for (double i = 40; i >= 31; i--) {

                    //Create File object for the file 
                    File outFile = new File("temperature_table.text");

                    //Create the PrintWriter object
                    PrintWriter pw = new PrintWriter(outFile);

                    pw.println("celsius  \tFahrenheit \t|       Fahrenheit \tCelsius");
                    double cTf = (double) Math.round(celsiusToFahrenheit(i) * 100) / 100;
                    double decimal = (double) Math
                            .round(fahrenheitToCelsius(j) * 100) / 100;
                    pw.println(i + "\t\t" + cTf + "\t\t|" + "\t" + j + "\t" + "\t"
                            + decimal);
                    System.out.println("");
                    j -= 10;

                    pw.close();
                }

            }

        }

        // • Converts a Celsius value to Fahrenheit
        public static double celsiusToFahrenheit(double celsius) {

            return (9.0 / 5) * celsius + 32;

        }

        // Converts a Fahrenheit value to Celsius
        public static double fahrenheitToCelsius(double fahrenheit) {

            return (5.0 / 9) * (fahrenheit - 32);

        }
    }

This is what I am getting:

 //       celsius   Fahrenheit  |       Fahrenheit  Celsius
 //       31.0      87.8        |   30.0        -1.11

I need to get this:

 //  celsius      Fahrenheit    | Fahrenheit     Celsius
 //   40.0      104.0       |   120.0       48.89
 //   39.0      102.2       |   110.0       43.33
 //   38.0      100.4       |   100.0       37.78
 //   37.0      98.6        |   90.0        32.22
 //   36.0      96.8        |   80.0        26.67
 //   35.0      95.0        |   70.0        21.11
 //   34.0      93.2        |   60.0        15.56
 //   33.0      91.4        |   50.0        10.0
 //   32.0      89.6        |   40.0        4.44
 //   31.0      87.8        |   30.0        -1.11   

I am getting only the last row of my table on the text file. I need to show the whole output on my text file.

Answer 1

You should open and close the PrintWriter outside the loop :

            File outFile = new File("temperature_table.text");
            PrintWriter pw = new PrintWriter(outFile);
            for (double i = 40; i >= 31; i--) {                   

                pw.println("celsius  \tFahrenheit \t|       Fahrenheit \tCelsius");
                double cTf = (double) Math.round(celsiusToFahrenheit(i) * 100) / 100;
                double decimal = (double) Math
                        .round(fahrenheitToCelsius(j) * 100) / 100;
                pw.println(i + "\t\t" + cTf + "\t\t|" + "\t" + j + "\t" + "\t"
                        + decimal);
                System.out.println("");
                j -= 10;
            }
            pw.close();

Currently, in each iteration of the loop you are overwriting the output file.