Question

Hello,

How can I make the program print out "Invalid data!!" and nothing else if the file has a grade that is not an A, B, C, D, E, or F or a percentage below zero? I need this done by tomorrow if possible please.

The program should sort a file containing data about students like this for five columns: one for last name, one for first name, one for student ID, one for student grade percentage, one for student grade.

Smith Kelly 438975 98.6 A

Johnson Gus 210498 72.4 C

Reges Stu 098736 88.2 B

Smith Marty 346282 84.1 B

Reges Abe 298575 78.3 C

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Here is the program.

DRIVER CLASS:

package pkg13_3;
import java.util.*;
import java.io.*;
public class Main {

/**
* @param args the command line arguments
*/
public static void main(String[] args) throws FileNotFoundException,
InputMismatchException{
try
{
Scanner scan = new Scanner(new File("files.txt"));
ArrayList <Student> elements = new ArrayList<Student>();
  
while(scan.hasNext())
{

String last = scan.next();
String first = scan.next();
int idNum = scan.nextInt();
double perecent = scan.nextDouble();
String grade = scan.next();
elements.add(new Student(last, first, idNum, perecent, grade));
  
}
Student[]element = new Student[elements.size()];
for(int i = 0; i<element.length;i++)
{
element[i] = elements.get(i);
}
System.out.println("Student data by last name: ");
Arrays.sort(element, new LastNameComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
  
System.out.println("Student data by first name: ");
Arrays.sort(element, new FirstNameComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
  
System.out.println("Student data by student id: ");
Arrays.sort(element, new IDComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
  
System.out.println("Student data by percentage: ");
Arrays.sort(element, new PercentageComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
  
System.out.println("Student data by percentage: ");
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
System.out.println("Student data by grade: ");
Arrays.sort(element, new GradeComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[(element.length - 1) -i].toString());
}
  
break;
}
catch(FileNotFoundException e)
{
System.out.println(e.toString());
}
  
catch(InputMismatchException f)
{
System.out.println(f.toString());
}
}
}
STUDENT CLASS:

package pkg13_3;

/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/

/**
*
* @author user
*/
public class Student {
String firstName, lastName;
int idNum;
double percent;
String grade;
  
public Student(String myFirstName, String myLastName, int id, double pct,
String myGrade)
{
lastName = myFirstName;
firstName = myLastName;
idNum = id;
percent = pct;
grade = myGrade;
  
}
public String getLastName()
{
return lastName;
}
  
public String getFirstName()
{
return firstName;
}
  
public int getID()
{
return idNum;
}
  
public double getPercentage()
{
return percent;
}
  
public String getGrade()
{
return grade;
}
  
public String toString()
{
return lastName + "\t" + firstName + "\t" + idNum + "\t" +
percent + "\t" + grade;

}
}
-------------------------------------------------------------------------------------

LastNameComparator:

/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package pkg13_3;
import java.util.*;
/**
*
* @author user
*/
public class LastNameComparator implements Comparator< Student>{
public int compare(Student student1, Student student2)
{
return student1.getLastName().compareTo(student2.getLastName());
}
}

-----------------------------------------------------------------------------------------------------------

First name comparator

--------------------------------------------------------------------------------------------------------------

package pkg13_3;
import java.util.*;
/**
*
* @author user
*/
public class FirstNameComparator implements Comparator< Student>{
public int compare(Student student1, Student student2)
{
return student1.getFirstName().compareTo(student2.getFirstName());
}
}

---------------------------------------------------------------------------------------------------------------

/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package pkg13_3;
import java.util.*;
/**
*
* @author user
*/
public class IDComparator implements Comparator< Student>{
public int compare(Student student1, Student student2)
{
return student1.getID() - (student2.getID());
}
}

-------------------------------------------------------------------------------------------------

Percentage Comparator

_____________________________________________________________

package pkg13_3;
import java.util.*;
/**
*
* @author user
*/
public class PercentageComparator implements Comparator< Student>{
public int compare(Student student1, Student student2)
{
return (int)(student1.getPercentage() - (student2.getPercentage()));
}
}

------------------------------------------------------------------------------------------------------

Grade Comparator:

package pkg13_3;
import java.util.*;
/**
*
* @author user
*/
public class GradeComparator implements Comparator< Student>{
public int compare(Student student1, Student student2)
{
return student1.getGrade().compareTo(student2.getGrade());
}
}

Answer 1

//Updated Driver Code

package pkg13_3;
import java.util.*;
import java.io.*;
public class Main {

/**
* @param args the command line arguments
*/
public static void main(String[] args) throws FileNotFoundException,
InputMismatchException{
try
{
Scanner scan = new Scanner(new File("files.txt"));
ArrayList <Student> elements = new ArrayList<Student>();
  
while(scan.hasNext())
{

String last = scan.next();
String first = scan.next();
int idNum = scan.nextInt();
double perecent = scan.nextDouble();
String grade = scan.next();

if((grade.equals("A")||grade.equals("B")||grade.equals("C")||grade.equals("D")||grade.equals("F"))&&perecent>0){}
else{System.out.println("Invalid data in input file!!");
System.exit(0);
}

elements.add(new Student(last, first, idNum, perecent, grade));
  
}
Student[]element = new Student[elements.size()];
for(int i = 0; i<element.length;i++)
{
element[i] = elements.get(i);
}
System.out.println("Student data by last name: ");
Arrays.sort(element, new LastNameComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
  
System.out.println("Student data by first name: ");
Arrays.sort(element, new FirstNameComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
  
System.out.println("Student data by student id: ");
Arrays.sort(element, new IDComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
  
System.out.println("Student data by percentage: ");
Arrays.sort(element, new PercentageComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
  
System.out.println("Student data by percentage: ");
for(int i = 0; i<element.length; i++)
{
System.out.println(element[i].toString());
}
System.out.println("Student data by grade: ");
Arrays.sort(element, new GradeComparator());
for(int i = 0; i<element.length; i++)
{
System.out.println(element[(element.length - 1) -i].toString());
}
  
//break;
}
catch(FileNotFoundException e)
{
System.out.println(e.toString());
}
  
catch(InputMismatchException f)
{
System.out.println(f.toString());
}
}
}