1. Write a Java program that outputs a list of students from the given data file

Question

1. Write a Java program that outputs a list of students from the given data file. Download the data file (student.txt) from our web site to the same folder as your program. You have to input the name of the data file from keyboard. You have to use input.hasNext()or input.hasNextInt() or input.hasNextDouble()with while loop when your program reads tokens from the file. We are assuming that you don’t know how many lines in the data file. The file contains student name followed by gender and age.

You also have to input (from keyboard) f or female if you want to print a list of female students, and m or male if you want print a list of male students.

Your program outputs the student’s name and total number of students of the gender and their average age.

For example if your data file contains the following data:

1 John m 18

2 William m 22

3 Susan f 21

4 Jack m 19

5 Jennifer f 18

Your program should produce the following output: What is the file name? student.dat

Which gender do you want? female Susan Jennifer We have 2 female students. Average age is 19.5.

Explanation / Answer

StudentDataRead.java

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class StudentDataRead {

  
   public static void main(String[] args) throws FileNotFoundException {
       Scanner scan1 = new Scanner(System.in);
       System.out.print("What is the file name? ");
       String fileName = scan1.next();
       File file = new File(fileName);
       if(file.exists()){
           System.out.print("Which gender do you want? ");
           String gender = scan1.next();
           char g='';
           if(gender.equalsIgnoreCase("male")){
               g = 'm';
           }
           else{
               g='f';
               }
           int count = 0;
           int sum = 0;
           Scanner scan = new Scanner(file);
           while(scan.hasNextLine()){
               scan.nextInt();
               String s = scan.next();
               if(scan.next().charAt(0) == g){
                   count++;
               System.out.print(s+" ");
               sum = sum + scan.nextInt();
               }
               else{
                   scan.nextInt();
               }
              
           }
           double avergae = sum/(double)count;
System.out.println("We have "+count+" "+gender+" students. Average age is "+avergae);
       }
       else{
           System.out.println("File does not exist");
       }
   }

}

Output:

What is the file name? D:\student.txt
Which gender do you want? female
Susan Jennifer We have 2 female students. Average age is 19.5

What is the file name? D:\student.txt
Which gender do you want? male
John William Jack We have 3 male students. Average age is 19.666666666666668

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