Need help with this simple Java code

[Jackofallnutz]

Hello.

Taking a Java course, but I have been stuck on this code for over a week, and its already due. My problem is, is that I have declared global variables, but the local variables are never read. The program is designed to take course hours and grade and spit out the GPA.

Input should be:


LAB07 BASIC VERSION


Enter course 1 Grade ===>> A
enter course 1 Hours ===>> 4
Enter course 2 Grade ===>> A
enter course 2 Hours ===>> 3
Enter course 3 Grade ===>> A
enter course 3 Hours ===>> 2
Enter course 4 Grade ===>> A
enter course 4 Hours ===>> 1

Course1 Grade: A Course1 Credit Hours: 4
Course2 Grade: A Course2 Credit Hours: 3
Course3 Grade: A Course3 Credit Hours: 2
Course4 Grade: A Course4 Credit Hours: 1

Current GPA: 4.0

Everything current works, except for the "Current GPA: 0".. It needs to have "4.0" and have all variables read.



Current code is below:




//CODE BEGINS

import java.util.*;

public class Lab07
{

static String lGrade1, lGrade2, lGrade3, lGrade4;
static int cHours1,cHours2,cHours3,cHours4;
static int cVal1, cVal2, cVal3, cVal4;
static int gradeValue, courseValue;
static int gVal1, gVal2, gVal3, gVal4;
static int value;
static int gpa;
static String dummy;


public static void main (String args[])
{
System.out.println("\nLAB07 BASIC VERSION\n\n");
enterData();
computeGPA();
displayData();
gradeValue();
courseValue();
getGPA();
}




public static void enterData()
{
Scanner in = new Scanner(System.in);
System.out.print("Enter course 1 Grade ===>> ");
lGrade1 = in.nextLine();
System.out.print("enter course 1 Hours ===>> ");
cHours1 = in.nextInt(); dummy = in.nextLine();
System.out.print("Enter course 2 Grade ===>> ");
lGrade2 = in.nextLine();
System.out.print("enter course 2 Hours ===>> ");
cHours2 = in.nextInt(); dummy = in.nextLine();
System.out.print("Enter course 3 Grade ===>> ");
lGrade3 = in.nextLine();
System.out.print("enter course 3 Hours ===>> ");
cHours3 = in.nextInt(); dummy = in.nextLine();
System.out.print("Enter course 4 Grade ===>> ");
lGrade4 = in.nextLine();
System.out.print("enter course 4 Hours ===>> ");
cHours4 = in.nextInt(); dummy = in.nextLine();
}
public static void computeGPA()
{

int value = 0;

char lg1 = lGrade1.charAt(0);
switch(lg1)
{
case 'A': value = 4; break;
case 'B': value = 3; break;
case 'C': value = 2; break;
case 'D': value = 1; break;
case 'F': value = 0; break;
}
int gVal1 = value;

char lg2 = lGrade2.charAt(0);
switch(lg2)
{
case 'A': value = 4; break;
case 'B': value = 3; break;
case 'C': value = 2; break;
case 'D': value = 1; break;
case 'F': value = 0; break;
}
int gVal2 = value;

char lg3 = lGrade3.charAt(0);
switch(lg3)
{
case 'A': value = 4; break;
case 'B': value = 3; break;
case 'C': value = 2; break;
case 'D': value = 1; break;
case 'F': value = 0; break;
}

int gVal3 = value;

char lg4 = lGrade4.charAt(0);
switch(lg4)
{

case 'A': value = 4; break;
case 'B': value = 3; break;
case 'C': value = 2; break;
case 'D': value = 1; break;
case 'F': value = 0; break;
}
}

public static void gradeValue()
{
int gVal4 = value;
}

public static void courseValue()
{
int cVal1 = gVal1 * cHours1;
int cVal2 = gVal2 * cHours2;
int cVal3 = gVal3 * cHours3;
int cVal4 = gVal4 * cHours4;

double totalValue = cVal1 + cVal2 + cVal3 + cVal4;
double totalHours = cHours1 + cHours2 + cHours3 + cHours4;
double gpa = totalValue / totalHours;
}

public static void displayData()
{
System.out.println();
System.out.println("Course1 Grade: " + lGrade1 + " Course1 Credit Hours: " + cHours1);
System.out.println("Course2 Grade: " + lGrade2 + " Course2 Credit Hours: " + cHours2);
System.out.println("Course3 Grade: " + lGrade3 + " Course3 Credit Hours: " + cHours3);
System.out.println("Course4 Grade: " + lGrade4 + " Course4 Credit Hours: " + cHours4);
System.out.println();
}

public static void getGPA()
{
System.out.println("Current GPA: " + gpa);
}
}

[keang]

If you declare local variables with the same name as class variables you will invariably end up assigning a value to the wrong variable. Change the names of your local variables to unique names and you will see which variables you are assigning which value to.

[Jackofallnutz]

If you declare local variables with the same name as class variables you will invariably end up assigning a value to the wrong variable. Change the names of your local variables to unique names and you will see which variables you are assigning which value to.

Thanks for the quick reply. Unfortunately, I can not change the names of my local variables. They have to remain those names by instructions from my course.

Any further advise?

Thanks again!

[keang]

Unfortunately, I can not change the names of my local variables. They have to remain those names by instructions from my course.

Change the names of the class variables then.

It's generally considered bad practice to use the same names for variables with overlapping scope. So much so that many IDE's warn you of the danger when you do this.

If your tutor has really specified that you must have class and local variables of the same name then the point of the exercise may be to show you how confusing it is. If not, find yourself another tutor.

If you still have to do this with the existing names then you need to look at every use of your local variables and see which of the two variables (ie local or class) you are using. If there is ambiguity over which one to use Java will always use the variable with the most local scope. For instance in method computeGPA() all your uses of 'value' will be the local variable and not the class variable. If you want to use the class variable you have to explicitly state that by using the class name ie Lab07.value

[Jackofallnutz]

Thank you very much. I will consult with my tutor and continue to look over my code, and go from there.