Question

Please provide the full code...the skeleton is down below:

Note: Each file must contain an int at the beginning, stating the number of records in the file. Afterwards, the number of records in the file will follow. Each record that follows will consist of a last name (String), and a gpa (double). However, to test the error handling of your program, the number of records will not always match the int value. All possible combinations should be tested.

1.) Prompt the user for menu option, relating to the file the program will input to test error handling logic.

2.) From the int value at the beginning of the file, create a 1-D array of Student objects, with the size of the int value. The student object consists of a String with lastName and a double with gpa.

3.) Load all the Student objects onto the array.

4.) Calculate the lowest, highest, sum, and average of all the gpa’s (doubles) in the array.

5.) Print out all the statistics:

        a.) The student with the lowest gpa is: xyz with gpa of: ###
        b.) The student with the highest gpa is: abc with gpa of: ###
        c.)   The average of all students’ gpa is: ###

6.) Include exception handling as follows:

In main method:

put try-catch block inside a tryAgain Loop, and catch the exceptions that were thrown by the 2 methods called in the try block (processFile and summarizeResults)

a.) FileNotFoundException (retry)
b.) InputMismatchException (no retry)
c.) BadDataException (no retry)
d.) NoSuchElementException (no retry)
e.) Exception (no retry)

In processFile method:

put try-catch block inside a do-loop, and catch the exceptions possible. Some can be handled here, but most are thrown back to main for handling:

a.) InputMismatchException - handled locally - non-numeric menu item selected
b.) FileNotFoundException - thrown back to main
c.) InputMismatchException - first num in file not numeric
- throw back to main

d.) BadDataException - actualNumRecs > numRecs stated in file - throw back to main
e.) InputMismatchException - second num in record is not a double - throw back to main
f.) NoSuchElementException - when a record does not have a gpa field - throw back to main
g.) Exception - for everything else - go back to main
h.)   Include a finally clause to close the file

In summarizeResults method:

put try-catch block outside, for-loop inside try
a.) catch Exception - throw back to main

7.) Create a new class, BadDataException which extends RuntimeException or Exception class. The class is composed of a default constructor, and an overloaded constructor that receives a String message. That constructor calls the super(message) constructor, passing it the String message.

8.) In the comments, list the names of the files that will fulfill each test case, to go through all the possible errors in the program. For example:

a.) abc.txt file name that doesn't exist.
b.) xyz.txt file has bad data in it (i.e. letters instead of numbers)
c.) lmn.txt file is empty
d.) ijk.txt file has valid data

9.) In the Project folder, provide a file for each of the test cases displayed by the menu.

Skeleton

package errorhandlingexample;

public class Student {
  
private String lastName;
private double gpa;
  
public Student(String ln, double aGPA)
{
lastName = ln;
gpa = aGPA;
}

public String getLastName() {
return lastName;
}

public double getGpa() {
return gpa;
}

public void setLastName(String lastName) {
this.lastName = lastName;
}

public void setGpa(double gpa) {
this.gpa = gpa;
}

public String toString() {

return "Student{" + "lastName=" + lastName + ", gpa=" + gpa + '}';
}
  }

package errorhandlingexample;

/**
*
* @author mtsguest
*/
public class BadDataException extends RuntimeException {
  
public BadDataException()
{
super();
}
public BadDataException(String message)
{
super(message);
}
  }

package errorhandlingexample;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class ErrorHandlingExample {

public static void main(String[] args) {
boolean tryAgain = true;
ErrorHandlingExample errorHandle1 = new ErrorHandlingExample();
while (tryAgain)
{
try
{
errorHandle1.processFile();
errorHandle1.summarizeResults();
tryAgain = false;
}
catch (FileNotFoundException e)
{
tryAgain = true;
System.out.println(e.getMessage());
}
catch (InputMismatchException e)
{
tryAgain = false;
System.out.println(e.getMessage());
}
catch (BadDataException e)
{
tryAgain = false;
System.out.println(e.getMessage());
}
catch (NoSuchElementException e)
{
tryAgain = false;
System.out.println(e.getMessage());
}
catch (Exception e)
{
tryAgain = false;
System.out.println(e.getMessage());
}

}
}
  
public void processFile() throws FileNotFoundException
{
boolean validMenu = false;
int usersChoice = 0;
Scanner keyboard = new Scanner(System.in);
  
while (!validMenu)
{
try
{
displayMenu();
usersChoice = keyboard.nextInt();
if (usersChoice < 1 || usersChoice > 6)
{
System.out.println("Your selection is invalid. Enter 1 - 6.");
validMenu = false;
}
else
{
actualFileProcess(usersChoice);
validMenu = true;
}
  
}
catch(InputMismatchException e)
{
validMenu = false;
keyboard.nextLine();
System.out.println("Incorrect menu selection.");
}
}
}
public void actualFileProcess(int usersChoice) throws FileNotFoundException
{
String fileName;
String badData1 = "goodFile.txt";
String badData2 = "tooFewRecs.txt";
String badData3 = "tooManyRecs.txt";
String badData4 = "nonNumericsRecCounter.txt";
String badData5 = "invalidData.txt";
String badData6 = "xyz.txt";
  
switch (usersChoice)
{
case 1:
fileName = badData1;
break;
case 2:
fileName = badData2;
break;
case 3:
fileName = badData3;
break;
case 4:
fileName = badData4;
break;
case 5:
fileName = badData5;
break;
case 6:
fileName = badData6;
break;
default:
fileName = badData1;
}
  
try
{
File aFile = new File(fileName);
Scanner myFile = new Scanner(aFile);


}
catch (FileNotFoundException e)
{
throw new FileNotFoundException("The file " + fileName + " was not found.");
//System.out.println("WROng!");
}
catch (InputMismatchException e)
{

}
catch (BadDataException e)
{
  
}
catch (NoSuchElementException e)
{

}
catch (Exception e)
{

}
}   
public void displayMenu()
{
System.out.println("What type of file do you wish to read?");
System.out.println("1. Good File");
System.out.println("2. Too few recs in the counter (more recs than anticipated");
System.out.println("3. Too many recs in the counter (less recs than anticipated");
System.out.println("4. Non-numeric record counter");
System.out.println("5. Invalid data in record - ex. GPA non-numeric");
System.out.println("6. Invalid file name");
  
}
  
public void summarizeResults()
{
  
}
  
}

Answer 1

package errorhandlingexample;

public class Student {

private String lastName;
private double gpa;

public Student(String ln, double aGPA) {
lastName = ln;
gpa = aGPA;
}

public String getLastName() {
return lastName;
}

public double getGpa() {
return gpa;
}

public void setLastName(String lastName) {
this.lastName = lastName;
}

public void setGpa(double gpa) {
this.gpa = gpa;
}

public String toString() {
return lastName + "with gpa of " + gpa + ".";
}
}

package errorhandlingexample;

/**
*
* @author mtsguest
*/
public class BadDataException extends RuntimeException {

public BadDataException() {
super();
}

public BadDataException(String message) {
super(message);
}
}

package errorhandlingexample;

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

public class ErrorHandlingExample {

File aFile;
Scanner myfile;

public static void main(String[] args) {
boolean tryAgain = true;
ErrorHandlingExample errorHandle1 = new ErrorHandlingExample();
while (tryAgain) {
try {
errorHandle1.processFile();
errorHandle1.summarizeResults();
tryAgain = false;
} catch (FileNotFoundException e) {
tryAgain = true;
System.out.println(e.getMessage());
} catch (InputMismatchException e) {
tryAgain = false;
System.out.println(e.getMessage());
} catch (BadDataException e) {
tryAgain = false;
System.out.println(e.getMessage());
} catch (NoSuchElementException e) {
tryAgain = false;
System.out.println(e.getMessage());
} catch (Exception e) {
tryAgain = false;
System.out.println(e.getMessage());
}
}
}

public void processFile() throws FileNotFoundException {
boolean validMenu = false;
int usersChoice = 0;
Scanner keyboard = new Scanner(System.in);

while (!validMenu) {
try {
displayMenu();
usersChoice = keyboard.nextInt();
if (usersChoice < 1 || usersChoice > 6) {
System.out.println("Your selection is invalid. Enter 1 - 6.");
validMenu = false;
} else {
actualFileProcess(usersChoice);
validMenu = true;
}

} catch (InputMismatchException e) {
validMenu = false;
keyboard.nextLine();
System.out.println("Incorrect menu selection.");
}
}
}

public void actualFileProcess(int usersChoice) throws FileNotFoundException {
String fileName;
String badData1 = "f://goodFile.txt";
String badData2 = "f://tooFewRecs.txt";
String badData3 = "f://tooManyRecs.txt";
String badData4 = "f://nonNumericsRecCounter.txt";
String badData5 = "f://invalidData.txt";
String badData6 = "f://xyz.txt";

switch (usersChoice) {
case 1:
fileName = badData1;
break;
case 2:
fileName = badData2;
break;
case 3:
fileName = badData3;
break;
case 4:
fileName = badData4;
break;
case 5:
fileName = badData5;
break;
case 6:
fileName = badData6;
break;
default:
fileName = badData1;
}

try {
aFile = new File(fileName);
myfile = new Scanner(aFile);
} catch (FileNotFoundException e) {
throw new FileNotFoundException("The file " + fileName + " was not found.");
//System.out.println("WROng!");
} catch (InputMismatchException e) {

} catch (BadDataException e) {

} catch (NoSuchElementException e) {

} catch (Exception e) {
}

}

public void displayMenu() {
System.out.println("What type of file do you wish to read?");
System.out.println("1. Good File");
System.out.println("2. Too few recs in the counter (more recs than anticipated)");
System.out.println("3. Too many recs in the counter (less recs than anticipated)");
System.out.println("4. Non-numeric record counter");
System.out.println("5. Invalid data in record - ex. GPA non-numeric");
System.out.println("6. Invalid1 file name");

}

public void summarizeResults() {
try {
Student[] s = new Student[myfile.nextInt()];
int max = 0, min = 0;
double avg = 0;

for (int i = 0; i < s.length; i++) {
s[i] = new Student(myfile.next(), myfile.nextDouble());
if (s[i].getGpa() > s[max].getGpa()) {
max = i;
}
if (s[i].getGpa() < s[min].getGpa()) {
min = i;
}
avg += s[i].getGpa();
}
System.out.println("The student with the lowest gpa is: " + s[min].toString());
System.out.println("The student with the highest gpa is: " + s[max].toString());
System.out.println("The average of all students’ gpa is: " + avg / s.length);

} catch (Exception ex) {
throw ex;
}
}

}

output:

c3 (Build, Run) #2 x Expertques (un) X run: What type of file do you wish to read? 1. Good File 2. Too few recs in the counter (more recs than anticipated) 3. Too many recs in the counter (less recs than anticipated) 4. Non-numeric record counter 5. Invalid data in record ex. GPA non-numeric 6. Invalid! file name 1 The student with the lowest gpa is: wwwwith gpa of 1.0. The student with the highest gpa is: refgwith gpa of 8.0. The average of all students' gpa is: 4.8 BUILD SUCCESSFUL (total time: 5 seconds)

good file

5
sed 5
defg 6
www 1
qart 4
refg 8

toofewrecords

10
sed 5
defg 6
www 1
qart 4
refg 8

tomanyrecord

2
sed 5
defg 6
www 1
qart 4
refg 8

invalid data

5
sed ten
defg six
www one
qart four
refg eight

nonnumericrecordcounter

five
sed 5
defg 6
www 1
qart 4
refg 8