Question

Create an Java application that uses a class to convert number grades to letter grades and another class for data validation.

Specifications

• The Grade class should have only one Instance Variable of type int.
• Use a class named Grade to store the data for each grade. This class should include these three methods:

  public void setNumber(int number)   public int getNumber()

  public String getLetter()

• The Grade class should have two constructors. The first one should accept no parameters and set the initial value of the number instance variable to zero. The second should accept an integer value and use it to set the initial value of the number instance variable.
• The grading criteria are as follows:

A 88-100
B 80-87
C 67-79
D 60-66
F <60

• Use the Console class presented in chapter 7 or an enhanced version of it to get and validate the user’s entries.
• Overload the getString() method of the Console class to add the ability to require a string value, and to require one of two specified string values.
• When the user responds to the Continue prompt, the application should only accept a value of “y” or “n”.
• Use ch07_LineItem for concept of different classes and using Console class for application.

im having some issue getting the overloading of the three string functions to pass values and validate the required entry validation

public class Console {

// require the user to input a value
public static String getString(String prompt) {
return getString(prompt, false);

}

// check that an input has been entered if not return an error   

public static String getString(String prompt, boolean required) {
String choice = "";
Scanner scanner = new Scanner(System.in);

//repeat until a valid input is entered
while (true) {
System.out.print(prompt);
if (choice.isEmpty() && required == true) {
choice = scanner.next();
if (scanner.hasNext()) {
choice = scanner.next();
System.out.println("Error! y or n. Try again.");
}
} else{
}
scanner.nextLine(); // discard any other data entered on the line
}
return getString(prompt,"y", "n");
}

// require one of two specified string values.

public static String getString(String prompt, String choiceOne, String choiceTwo) {
String choice = "";
boolean isValid = false;
Scanner scanner = new Scanner(System.in);

//repeat until a valid input is entered
while (!isValid) {
System.out.print(prompt);

if (scanner.hasNext()) {
choice = scanner.next(); // read user entry
//check if valid input is entered, if yes set isValid to true
if (choice.equalsIgnoreCase(choiceOne) || choice.equalsIgnoreCase(choiceTwo)) {
isValid = true;
} else { //else display error message
System.out.println("Error! y or n. Try again.");
}
} else {

System.out.println("Error! y or n. Try again.");
}
scanner.nextLine(); // discard any other data entered on the line
}
return choice;
}

public static int getInt(String prompt) {
int i = 0;
boolean isValid = false;
Scanner scanner = new Scanner(System.in);

while (!isValid) {
System.out.print(prompt);
if (scanner.hasNextInt()) {
i = scanner.nextInt();
isValid = true;

} else {
System.out.println("Error! Invalid integer. Try again.");
}
scanner.nextLine(); // discard any other data entered on the line
}

return i;

}
}

import java.util.Scanner;

public class Grade {

private int grade;

Grade() {
grade = 0;
}

Grade(int marks) {
this.grade = marks;
}

public void setNumber(int number) {
this.grade = number;
}

public String getLetter() {
if (grade >= 88) {
return "A";
} else if (grade >= 80) {
return "B";
} else if (grade >= 67) {
return "C";
} else if (grade >= 60) {
return "D";
} else if (grade < 60) {
return "F";
}
return "";
}

public String toString() {
return "Letter Grade : " + getLetter();
  
}
}

public class Main {

/**
* @param args the command line arguments
*/
public static void main(String[] args) {

System.out.println("Welcome to the Letter Grade Converter");
System.out.println();

String choice = "y";
  
while (choice.equalsIgnoreCase("y")) {

  
  
int myGrade = Console.getInt("Enter numerical grade: ");
Grade grade = new Grade(myGrade);
System.out.println("Letter grade: " + grade.getLetter());
  
  
choice = Console.getString("Continue? (y/n):");
  
}
}
}

Answer 1

Explanation::

• Change is in Console.java Code only
• Output is provided at the end of the code.

Code in JAVA:::

import java.util.Scanner;

public class Console {

   // require the user to input a value
   public static String getString(String prompt) {
       return getString(prompt, false);
   }

   // check that an input has been entered if not return an error   

   public static String getString(String prompt, boolean required) {
       return getString(prompt,"y", "n");
   }

   // require one of two specified string values.

   public static String getString(String prompt, String choiceOne, String choiceTwo) {
       String choice = "";
       boolean isValid = false;
       Scanner scanner = new Scanner(System.in);

       //repeat until a valid input is entered
       while (!isValid) {
           System.out.print(prompt);

           if (scanner.hasNext()) {
               choice = scanner.next(); // read user entry
               //check if valid input is entered, if yes set isValid to true
               if (choice.equalsIgnoreCase(choiceOne) || choice.equalsIgnoreCase(choiceTwo)) {
                   isValid = true;
               } else { //else display error message
                   System.out.println("Error! y or n. Try again.");
               }
           } else {

               System.out.println("Error! y or n. Try again.");
           }
           scanner.nextLine(); // discard any other data entered on the line
       }
       return choice;
   }

   public static int getInt(String prompt) {
       int i = 0;
       boolean isValid = false;
       Scanner scanner = new Scanner(System.in);

       while (!isValid) {
           System.out.print(prompt);
           if (scanner.hasNextInt()) {
               i = scanner.nextInt();
               isValid = true;

           } else {
               System.out.println("Error! Invalid integer. Try again.");
           }
           scanner.nextLine(); // discard any other data entered on the line
       }

       return i;

   }
}

OUTPUT::

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