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alwynmalan
alwynmalan

Reputation: 159

Java enumeration for grades

Good day people, I have an assignment to write a Java enumeration that represents letter grades A through F.

That if all good, with the following code that I use:

A(true), B(true),  C(true), D(true), E(true), F(false);

The Boolean value indicates whether the student has passed or failed.

The problem is that we need to include plus and minus grades. But I don't know how to structure it...A+ etc. doesn't work.

Any advice or help will be much appreciated.

Upvotes: 1

Views: 2347

Answers (4)

Nabeel Ahmed
Nabeel Ahmed

Reputation: 267

well try to used the class like below Note: this is the easy way to access the grade.

public class Grade {
    private Long id;
    // this will be the upper case store and read
    private String grade;
}

Upvotes: 0

Honza Zidek
Honza Zidek

Reputation: 20266

You will use the enum pattern. It works also with the plain class, the Java enum is just a syntactic sugar.

First the class solution, so you may compare it.

public class Grade {
    final public static Grade A = new Grade(true, "A");
    final public static Grade A_PLUS = new Grade(true, "A+");
    final public static Grade A_MINUS = new Grade(true, "A-");
    ...
    final public static Grade E = new Grade(true, "E");
    final public static Grade F = new Grade(false, "F");

    final private boolean passed;
    final private String name;

    // private constructor - no-one can create any other instance then those above
    private Grade(boolean passed, String name) {
        this.passed = passed;
        this.name = name;
    }

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

    @Override
    public String toString() {
        return this.name;
    }
}

Then for comparison the enum solution. You should understand the design pattern. Enum is just more convenient syntax + more reliable serializability, nothing more.

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

    final private boolean passed;

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

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

    // Thanks to special bonus functionality of enums, which are aware of their name
    @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;
        }
    }

}

Upvotes: 0

Prasad Kharkar
Prasad Kharkar

Reputation: 13566

As Kocko, answered, you cannot use A+ as + is an operator in java but you can override toString() method so that you can give some meaningful representation to enum type.

If you want you could use a string representation like A+ for enum A_PLUS using toString method. Learn more about enumeration in java

Upvotes: 0

Konstantin Yovkov
Konstantin Yovkov

Reputation: 62864

А+ doesn't work, because the + is an operator in Java.

Better add a few more grades, like:

A_PLUS(true), A_MINUS(true), .... , F_PLUS(false);

Upvotes: 3

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