Write an application which will write five student ID numbers and GPAs to a “rw”

Question

Write an application which will write five student ID numbers and GPAs to a “rw” file called “Stu.dat” and then allow you to display the GPA of any student upon entering their ID number, for any number of students.

Directions

• Import the classes necessary to support your application.

• Create a class called ReadWrite. This class has no properties or behaviors.

• Create a main method which will include the following:

Add an appropriate throws statement in the main method.

Create a reference to a text file called “Stu.dat” with “rw” access.

Include try and catch blocks for exception handling.

Use a loop to interactively assign student ID numbers and their GPA scores.

With the use of a second loop, display the GPA for specific student ID numbers.

Use a sentinel to determine when you wish to stop the program.

Include a finally block within your program.

Explanation / Answer

//Here is the Source code to copy . Please refer Comments.

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.PrintWriter;

import java.util.HashMap;

import java.util.Scanner;

public class ReadWrite {

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

       HashMap<Integer, Float> hm = new HashMap();

       File extractFile = new File("Student.dat");

       FileWriter fileWriter = new FileWriter(extractFile, true);

       PrintWriter printWriter = new PrintWriter(

               new BufferedWriter(fileWriter));

       // to accept all inputs for StudentID and GPA Score

       try{

           for(int i=0; i<5; i++){

                  Scanner in = new Scanner(System.in);  

                  System.out.println("Enter a StudentID for Student " + i );

              int studenID = in.nextInt();

              System.out.println("You entered StudentID " + studenID);

              System.out.println("Enter a GPA score of Student " + i );

              float GPAScore = in.nextFloat();

              System.out.println("You entered GPA score "+ GPAScore);

              hm.put(studenID, GPAScore);

              printWriter.println("StudentID : " + studenID +" GPAScore : " + GPAScore );

               }

       } finally {

           // Make sure to close the file when done

           printWriter.close();

       }

       // to display Values From studen.dat File

       InputStream is = new FileInputStream("Student.dat");

       InputStreamReader isr = new InputStreamReader(is);

       BufferedReader br = new BufferedReader(isr);

       String Line=null;

       while((Line = br.readLine()) != null)

{

   // prints line

   System.out.println(Line);

}  

   }

}

---------------------------------------------Output For this ------------------------------------------------------------------

Enter a StudentID for Student 0

1

You entered StudentID 1

Enter a GPA score of Student 0

1.1

You entered GPA score 1.1

Enter a StudentID for Student 1

2

You entered StudentID 2

Enter a GPA score of Student 1

2.2

You entered GPA score 2.2

Enter a StudentID for Student 2

3

You entered StudentID 3

Enter a GPA score of Student 2

3.3

You entered GPA score 3.3

Enter a StudentID for Student 3

4

You entered StudentID 4

Enter a GPA score of Student 3

4.4

You entered GPA score 4.4

Enter a StudentID for Student 4

5

You entered StudentID 5

Enter a GPA score of Student 4

5.5

You entered GPA score 5.5

StudentID : 1 GPAScore : 1.1

StudentID : 2 GPAScore : 2.2

StudentID : 3 GPAScore : 3.3

StudentID : 4 GPAScore : 4.4

StudentID : 5 GPAScore : 5.5

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