String not initialised question

[Kevin M Brown]

Hi guys, I gotta problem with ma code :O
I'm doing a project that's based on an online results showing form.
The problem that I'm having is that it's bringing up an error message saying that variables aren't initialised, when they are.

Here's the code -

import java.util.*;

public class KevinBrown
{
    public static void main(String []args)
    {
        int choice;
        
        do
        {
                Scanner sc = new Scanner(System.in);
                String name;
                
                int stuNumber;
                int proGrade;
                int webGrade;
                int mathGrade;
                int critGrade;
                int opGrade;
                int arcGrade;
                
                System.out.println();
                System.out.println("Entering Student Details");
                System.out.println("------------------------");
                System.out.print("Student name:          ");
                name=sc.next();

                System.out.print("Student number:          ");
                stuNumber=sc.nextInt();
                    
                    int choice1done=0;
            
            System.out.println();
            System.out.println("Student Grade System");
            System.out.println("--------------------");
            System.out.println();
            System.out.println("      1) Enter Student Details");
            System.out.println("      2) Display Student Grades");
            System.out.println("      3) Display Student Statistics");
            System.out.println("      4) Display Full Transcript");
            System.out.println("      0) Exit System");
            System.out.println();
            System.out.print("Select an option [0-4]: ");
            choice=sc.nextInt();
            
            switch(choice)
            {

                case 1:
                choice1done=1;
                    do
                        { 
                            System.out.print("Programming grade:          ");
                            proGrade=sc.nextInt();
                            if(proGrade <0 || proGrade >100)
                            {
                                System.out.println("Please reenter your number");
                            }
                        }while(proGrade <0 || proGrade >100);

                    do
                        {    
                            System.out.print("Web development grade:          ");
                            proGrade=sc.nextInt();
                            if(proGrade <0 || proGrade >100)
                            {
                                System.out.println("Please reenter your number");
                            }
                        }while(proGrade <0 || proGrade >100);

                    do
                        {    
                            System.out.print("Mathematics grade:          ");
                            mathGrade=sc.nextInt();
                            if(mathGrade <0 || mathGrade >100)
                            {
                                System.out.println("Please reenter your number");
                            }
                        }while(mathGrade <0 || mathGrade>100);                

                    do
                        {    
                            System.out.print("Critical Thinking grade:          ");
                            critGrade=sc.nextInt();
                            if(critGrade <0 || critGrade >100)
                            {
                                System.out.println("Please reenter your number");
                            }
                        }while(critGrade <0 || critGrade >100);                        
                
                    do
                        {    
                            
                            System.out.print("Operating Systems grade:          ");
                            opGrade=sc.nextInt();
                            if(opGrade <0 || opGrade >100)
                            {
                                System.out.println("Please reenter your number");
                            }
                        }while(opGrade <0 || opGrade >100);                        
                        
                    do
                        {    
                            
                            System.out.print("Computer Architecture grade:          ");
                            arcGrade=sc.nextInt();
                            if(arcGrade <0 || arcGrade >100)
                            {
                                System.out.println("Please reenter your number");
                            }
                        }while(arcGrade <0 || arcGrade >100);
                        break;
                
                //-----------------------------------
                case 2:
                if(choice1done !=1)
                {
                    System.out.println();
                    System.out.print("No student details entered, please enter the student details via option 1");
                    System.out.println();
                    break;
                }
                
                 System.out.println();
                 System.out.println("Student (number): " + name +"(" + stuNumber + ")" );
                 System.out.println();
                 System.out.println();
                 
                 System.out.println("Semester 1 results");
                 System.out.println("------------------");
                 
                 System.out.print("Programming:     " + proGrade);
                 System.out.print("Web Development:     " + webGrade);
                 System.out.print("Mathematics:     " + mathGrade);
                 System.out.print("Critical Thinking:     " + critGrade);
                 System.out.print("Operating Systems:     " + opGrade);
                 System.out.print("Computer Architecture:     "+ arcGrade);
                 
                 System.out.println();
                
                break;
                
                //----------------
                case 3:
                break;
                
                default:
                 System.out.println();
                System.out.println("Please re-enter your choice");
                break;
            }
        }while(choice !=0);
        System.out.println();
        System.out.print("Thank you for using the System");
    }    
}    
    

The error is that the variable "name" a String, may not have been initialised.

I'm using BlueJ.

Any suggestions? It works fine while inputting code only, not showing it.

Thanks!

[Jeanne Boyarsky]

Name looks correct. YOu could try String name = sc.next() to get rid of any gap between declaration and initialization though.

However, searching your code for "webGrade" shows two references. The first is "int webGrade". Which declares it but doesn't initialize it. The other is where it gets printed out. Which won't compile because it is never set to a value.

[Kevin M Brown]

Jeanne Boyarsky wrote:Name looks correct. YOu could try String name = sc.next() to get rid of any gap between declaration and initialization though.

However, searching your code for "webGrade" shows two references. The first is "int webGrade". Which declares it but doesn't initialize it. The other is where it gets printed out. Which won't compile because it is never set to a value.

Thanks for pointing out the webGrade blunder, fixed it.

I tried the String name=sc.next() instead of creating the variable at the start, didn't work, same error "variable name might not have been initialised".

Any other suggestions?

-Kevin

[Jeff Verdegan]

viperkevin Yes wrote:
The problem that I'm having is that it's bringing up an error message saying that variables aren't initialised, when they are.

It's not lying. It's saying the variable might not have been initialized. That is, the compiler can't be sure that it has been initialized.

For example:

void foo() {
  int x = 5;
  int y;

  if (x > 0) {
    y = 1;
  }
  System.out.println(y);
}

void bar(int x) {
  if (x > 0) {
    y = 1;
  }
  else if (x < 0) {
    y = -1;
  }
  else if (x == 0) {
    y = 0;
  }

  System.out.println(y);
}

In both of the above cases, the compiler can't be sure that y will be initialized, so we'll get an error. Now, you and I can look at the code and say that all the cases are covered and y is definitely initialized, but that's because we're doing some semantic analysis that the compiler doesn't do.

Your code is far too long for me to read, but I guarantee you're doing something similar.

[Campbell Ritchie]

. . . Your code is far too long for me to read, . . .

So are your lines. //------- comments are bad style, and their length made the code difficult to read. Multiple blank lines also make the code difficult to read. I have corrected some of those errors.

If that is one single method, it is too long. It should be divided into separate methods. It is long enough to make at least six methods. Why have you got a blank case (3)?