Initialize variable error for java

Question

First of; I am very new to programming...

What i am trying to do is have a simple program which calculates your grade based on your marks, here is what i have right now:

 class Grade {

public static void main(String[]args){


char grade;


    int marks = 92;

    if(marks<60) 
    grade = 'F' ;

    else if(marks>61 && marks<69)
    grade = 'D';

    else if(marks>70 && marks<79)
    grade = 'C';

    else if(marks>80 && marks<89)
    grade = 'B';

    else if(marks>90 && marks<99)
    grade = 'A';

    else
    System.out.println("Bogus Grade");


    System.out.println("Your grade is " + grade);


}


}

(For now i'm just specifying the grade in the code, and will work on user input later)

While trying to compile the code I get this error:

  Grade.Java:30: error: variable grade might not have been initialized
                  System.out.println("Your grade is" + grade);
                                                       ^

Set the marks to 60 and you will see the problem. The grade variable needs to be set like char grade = 'I'; or something similar. Then fix your if/else blocks to handle the grades (e.g. <= instead of <). — gpojd
– gpojd, Commented Jul 15, 2014 at 21:15

AntonH · Accepted Answer · 2014-07-15 21:21:53Z

3

Because it's possible to get through all the cases and have grade not be set.

Set a value to grade at the start:

char grade = 'Z';

Also make sure all cases are taken care of, and grade set all the time. In the final else, grade is not modified. You can do:

else {
    System.out.println("Bogus Grade");
    grade = 'Z';
}

Also, values of marks equal to 60, 70, 80, 90 and 100 are never taken into account. You should change the if lines to:

else if(marks>=60 && marks<69)
...
else if(marks>=70 && marks<79)
...
else if(marks>=80 && marks<89)
...
else if(marks>=90 && marks<=100)
...
else {
    ...
}

edited Jul 15, 2014 at 21:21

answered Jul 15, 2014 at 21:15

AntonH

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2 Comments

gpojd Over a year ago

They also need to fix 70, 80, 90, and 100.

AntonH Over a year ago

@gpojd Yes, just noticed. Edited my answer.

rgettman · Accepted Answer · 2014-07-15 21:14:40Z

2

There are cases where grade isn't initialized. What if grade is 101? What if it's -1? In that case, the else block doesn't initialize grade, and Java won't allow a possible case where a local variable is not initialized before it is used.

You must explicitly initialize it, so initialize it to something when you declare it.

char grade = 'Z';

At the end, only print the grade if it was changed from 'Z':

if (grade != 'Z') {
   System.out.println("Your grade is " + grade);
}

answered Jul 15, 2014 at 21:14

rgettman

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Comments

MosesA · Accepted Answer · 2014-07-15 21:13:27Z

0

Put char grade = '0'; at the start.

Also use brackets since you are using a lot of if-statements. They can get pretty confusing after a while.

answered Jul 15, 2014 at 21:13

MosesA

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Comments

JamesB · Accepted Answer · 2014-07-15 21:17:11Z

0

Local variables are not initialised by default so you have to give them an initial value.

char grade = 'Z';

This only applies if you reach a point in your code where the variable could not have a value.

http://docs.oracle.com/javase/tutorial/java/nutsandbolts/variables.html

answered Jul 15, 2014 at 21:17

JamesB

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