I have the methods, but need program code for Grade enum

Question

I need to write a Java enumeration LetterGrade that represents letter grades A through F, including plus and minus grades. Now this is my enumeration code:

public enum Grade {
A(true),
A_PLUS(true),
A_MINUS(true),
B(true),
B_PLUS(true),
B_MINUS(true),
C(true),
D(true),
E(true),
F(false);

final private boolean passed;

private Grade(boolean passed) {
    this.passed = passed;
}

public boolean isPassing() {
    return this.passed;
}


@Override
public String toString() {
    final String name = name();
    if (name.contains("PLUS")) {
        return name.charAt(0) + "+"; 
    }
    else if (name.contains("MINUS")) {
        return name.charAt(0) + "-"; 
    }
    else {
        return name;
    }
}

What I am confused about is writing the main program. I think it could be quite straightforward but I have no clue on how to start it. I don't want the whole code. Just a few lines to give me a head start. The rest I will try to figure out on my own.

Answer 1

I imagine you have a Student class that looks like this:

class Student {

    protected Grade grade = null;  

    public Student(Grade g) {
        this.grade = g; 
     }
}

Then you simply add a method in this class calling the isPassing method from your enum:

public boolean isPassing() {
    if (this.grade != null) 
        return this.grade.isPassing();
    return false;
}

This is supposing the passed boolean in Grade are correctly set and are invariant.