Member Avatar for nicklbmx

So the problem comes in, in the last method called printComparisonResults. I just have no clue what to do?? Thanks for your time!


My Class:

//StudentRecord
 //Nick Elliott 02/01/10
 
 import java.util.Scanner;
 import java.io.*;


 
 // A StudentRecord contains a student's first name and their gpa
 public class StudentRecord
 {
 	private String name;
	private double gpa;
	
	//initialize record given to values
	public StudentRecord(String theName, double theGpa)
	{
		this.setName(theName);
		this.setGpa(theGpa);
	}
	// initialize the empty record
	public StudentRecord( )
	{
		this("",0);
	}
	// initialize record to values given in string
	public StudentRecord(String recordValues)
	{
		Scanner scanner = new Scanner(recordValues);
		this.setName(scanner.next());
		this.setGpa(scanner.nextDouble());
	}
	// name is set to theName
	public void setName(String theName)
	{
		this.name = theName;
	}
	// gpa is set to theGpa
	public void setGpa(double theGpa)
	{
		if(theGpa < 0.0 || theGpa > 4.0)
		{
			throw new RuntimeException(theGpa + " is out of the range, 0.0 - 4.0");
		}
		
		this.gpa = theGpa;
	}
	// returns name
	public String getName( )
	{
		return this.name;
	}
	// returns gpa
	public double getGpa( )
	{
		return this.gpa;
	}
	//returns string representation of record
	public String toString( )
	{
		return this.name + " " + this.gpa;
	}
}

Here is my application:

// FindAverageGpa
// Nick Elliott 2/2/10

import java.io.*;
import java.util.Scanner;

public class FindAverageGpa
{
	// read in a list of StudentRecords
	// print out the average gpa and whether each student's gpa is >= or <average
	public static void main(String[]args)throws IOException
	{
		final int MAX_SIZE = 10;
		StudentRecord[] student = new StudentRecord[ MAX_SIZE ];
		
		System.out.println(" Type in a list of students names and their Gpa's"
		+ " \nPress enter at blan line to stop");

		int size = readRecords( student );
		
		double averageGpa = calculateAverageGpa( student, size);
		
		System.out.println(" the average gpa is " + averageGpa);

		printComparisonResults( student, size, averageGpa);

}
	// interactively read in any number of StudentRecords (name gpa) into the student array
	// return the number of records read and stored
	public static int readRecords( StudentRecord[]student) throws IOException
	{
		Scanner scanner = new Scanner(System.in);

		String line = null;
		int count = 0;
		while(true)
		{
			line = scanner.nextLine();
			
			if(line.equals(""))
				break;
			
			data[count] = new StudentRecord (line);
			
			count++;
		}
		return count; // number of data elements stored
	}

	// returns the average gpa of the records stored in student[0...size-]
	public static double calculateAverageGpa(StudentRecord[]student, int size)
	{
		double sum = 0.0;
		int count = 0;

		while(count < size)
		{
			sum = sum + student[count].getGpa();
			count++;

		}
		double averageGpa = sum/size;
		return averageGpa;
	}
	
	// print out each StudentRecord and say whether that Student's gpa is >= or < averageGpa
	public static void printComparisonReults(StudentRecord[]student, int size, double averageGpa)
	{
		if(StudentRecord[theGpa] >= averageGpa) //this line has a problem
		{
			System.out.println(" The student record is greater than or equal to the average gpa.");
		}
		else
		{
			if(StudentRecord[theGpa] < averageGpa)//this line has a problem
			{
				System.out.println(" The student record is less than the average gpa.");
			}
		}
	}
}
  • 2 Contributors
  • 1 Reply
  • 181 Views
  • 6 Hours Discussion Span
  • Latest Post Latest Post by apegram

Dani AI

Generated

Several small but critical issues prevent compilation and correct results. The call from main is to printComparisonResults(...) while the defined method is misspelled printComparisonReults — the names must match. Inside the comparison method the code tries to compare a non-existent identifier and the class name (StudentRecord[theGpa]) to a double; that should be replaced by iterating the student array and calling getGpa() on each element. The input routine writes to an undefined array (data[count]) and has no bounds check, and calculateAverageGpa should guard against size == 0 to avoid division by zero. is correct that a loop is needed; the snippet below implements the loop and adds basic safety checks.

public static int readRecords(StudentRecord[] student) {
    Scanner in = new Scanner(System.in);
    int count = 0;
    while (count < student.length) {
        String line = in.nextLine();
        if (line.trim().isEmpty()) break;
        student[count++] = new StudentRecord(line);
    }
    return count;
}

public static double calculateAverageGpa(StudentRecord[] student, int size) {
    if (size == 0) return 0.0;
    double sum = 0.0;
    for (int i = 0; i < size; i++) sum += student[i].getGpa();
    return sum / size;
}

public static void printComparisonResults(StudentRecord[] student, int size, double averageGpa) {
    for (int i = 0; i < size; i++) {
        StudentRecord s = student[i];
        double g = s.getGpa();
        System.out.printf("%s: %.2f -> %s average%n",
            s.getName(), g, (g >= averageGpa) ? ">= " : "< ");
    }
}

Notes and pitfalls: if input names may contain spaces, the StudentRecord(String) constructor that uses Scanner.next() will only take the first token; either change the parsing or require a single-word name. Always check array bounds when reading, and format the average (and comparisons) for readability. These fixes address the compilation errors, runtime exceptions, and the logical comparison that highlighted.

Member Avatar for apegram 
// print out each StudentRecord and say whether that Student's gpa is >= or < averageGpa
	public static void printComparisonReults(StudentRecord[]student, int size, double averageGpa)
	{
		if(StudentRecord[theGpa] >= averageGpa) //this line has a problem
		{
			System.out.println(" The student record is greater than or equal to the average gpa.");
		}
		else
		{
			if(StudentRecord[theGpa] < averageGpa)//this line has a problem
			{
				System.out.println(" The student record is less than the average gpa.");
			}
		}
	}

First, the variable theGpa does not exist within this method. Second, from the comments, it appears that you want to iterate through each of the student records. Try wrapping a for loop around your if statements and use the loop variable in lieu of theGpa. Lastly, StudentRecord is not an array of doubles, it's not even an array. It's a type. Your array is student of type StudentRecord.

Keep at it.

Edited by apegram because: n/a
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