CODEWITHSUNDEEP
javainterfaceenums
user4117456
user4117456

Reputation:

Using an interface inside of an enum

I'm messing around with enumerations and interfaces, however i cannot seem to add the 'moneyType' interface i had implemented to the enum, i've been unable to find the solution. Basically: the moneyType is red underlined, and i can not find out how i can get it right!

package Se.lucas.Main;

public enum moneyTypes implements moneyType {

DOLLAR(moneyType, 15, "Dollar"),
 EURO(moneyType, 15, "Dollar"), 
  FRANK(moneyType, 15, "Dollar"),
   MARK(moneyType, 15, "Dollar"),
    POUND(moneyType, 15, "Dollar");

private moneyType type;
private int amount;
private String moneyName;

moneyTypes(moneyType type, int amount, String name) {
    type = this.type;
    amount = this.amount;
    name = this.name();
}


@Override
public int getMoney() {
    return this.amount;

}

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

@Override
public String getMessage() {
    return "got the message";
}

}

package Se.lucas.Main;

public interface moneyType {


public int getMoney();
public String getMoneyName();
public String getMessage();

}

I have not worked with enumeration and interfaces a lot yet.

Upvotes: 2

Views: 97

Answers (2)

nickb
nickb

Reputation: 59699

You don't need to pass moneyType in the enum list declaration, or have it in the constructor, just leave it out. The reason being each enum instance will be a moneyType. 

interface MoneyType {
    public int getMoney();
    public String getMoneyName();
    public String getMessage();
}

public enum MoneyTypes implements MoneyType {
    DOLLAR(15, "Dollar"), EURO(15, "Dollar"), FRANK(15, "Dollar"), MARK(15, "Dollar"), POUND(15, "Dollar");

    private final int amount;
    private final String moneyName;

    MoneyTypes(int amount, String name) {
        this.amount = amount;
        this.moneyName = name;
    }

    @Override
    public int getMoney() {
        return this.amount;
    }

    @Override
    public String getMoneyName() {
        // moneyName is assigned the value of name
        // You were returning name();
        // Two different values, decide which you want to return.
        return this.moneyName;
    }

    @Override
    public String getMessage() {
        return "got the message";
    }
}

Now you can do:

MoneyType type = MoneyTypes.DOLLAR;

Note that I changed the names of the interface and the enum declaration to conform to Java naming standards, specifically beginning with an uppercase letter. I also modified the fields of the enum to be final so they cannot be assigned after they are constructed.

Upvotes: 2

Walfrat
Walfrat

Reputation: 5353

This maybe ? 

package Se.lucas.Main;

public enum moneyTypes implements moneyType {

DOLLAR(15, "Dollar"),
 EURO(15, "Dollar"), 
  FRANK(15, "Dollar"),
   MARK(15, "Dollar"),
    POUND(15, "Dollar");

private int amount;
private String moneyName;

moneyTypes(int amount, String moneyName) {
     this.amount = amount;
     this.moneyName= moneyName;

}


@Override
public int getMoney() {
    return this.amount;

}

@Override
public String getMoneyName() {
    return this.moneyName;
}

@Override
public String getMessage() {
    return "got the message";
}

Note :

  1. You this were on the wrong side
  2. you used this.name() which would return something like DOLLAR in getMoneyName() instead of (i think) this.moneyName
  3. I renamed name to moneyName to not have conflict with enum name()

Final point : using an interface over an enum like this seems a bit too much, do you really need that interface ? You can add method to an enum without any interface.

Upvotes: 1

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