Saving Inputs to txt. file in Java

Question

I have been building program, where a. teacher is asked for information of 5. students and all the inputs should be saved after to a txt. file. Although my file is always created but is always empty... Could someone please help me find my mistake ?

import java.util.Scanner;
import java.io.PrintWriter;
import java.io.IOException;


public class programming_project_1 {
    public static void main(String[] args) throws IOException
    {    


        int numbersOfLoops = 1;

        Scanner scn = new Scanner(System.in);

        while (true){
            if (numbersOfLoops == 6){
                break;
            }

            System.out.println("First Name: " );

            String first_name = scn.next();

            System.out.println("Last Name: " );

            String last_name = scn.next();

            System.out.println("Final Score: ");

            int score = scn.nextInt();

            numbersOfLoops++ ;

            PrintWriter out = new PrintWriter("grades.txt");

            System.out.println("First Name: " + first_name);
            System.out.println("Last Name: " + last_name);
            System.out.println("Final Score: " +  score);

            out.close();

        }
    }
}

Federico klez Culloca · Accepted Answer · 2022-08-29 14:59:49Z

2

You never write to out. Here:

System.out.println("First Name: " + first_name);
System.out.println("Last Name: " + last_name);
System.out.println("Final Score: " +  score);

you probably meant out.println instead of System.out.println.

System.out is a PrintStream that writes to standard output. out, on the other hand, is a PrintWriter you declared and that writes to a file.

Also, you probably want to open the file before the loop and only close it afterwards, otherwise each iteration will overwrite the previous one.

Finally, a couple of asides:

that's a weird way of looping 5 times. You could use a for instead.
You should strive to respect java naming convention. Class names Start with an upper-case letter and use CamelCase, not snake_case. Same for variables, but they start with lower-case letters.

To sum it up:

import java.util.Scanner;
import java.io.PrintWriter;
import java.io.IOException;


public class ProgrammingProject1 {
    public static void main(String[] args) throws IOException
    {    
        Scanner scn = new Scanner(System.in);

        PrintWriter out = new PrintWriter("grades.txt");

        for (int i = 0; i < 5; i++) {

            System.out.println("First Name: " );
            String firstName = scn.next();

            System.out.println("Last Name: " );
            String lastName = scn.next();

            System.out.println("Final Score: ");
            int score = scn.nextInt();

            out.println("First Name: " + firstName);
            out.println("Last Name: " + lastName);
            out.println("Final Score: " +  score);

        }
        out.close();
    }
}

edited Aug 29, 2022 at 14:59

answered Aug 29, 2022 at 14:47

Federico klez Culloca

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3 Comments

Serdyna Over a year ago

Thank You overmuch for your help! Can you just please tell me why this "out.println("First Name: " + first_name);" should be without "System" at the beginning ?

OscarRyz Over a year ago

@Serdyna because out is a variable that will write to the grades.txt file, while System.out is a variable that will write to the System console.

Federico klez Culloca Over a year ago

@Serdyna I added an explanation about that directly in the answer.

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