CODEWITHSUNDEEP
javanetbeans
Moawiya
Moawiya

Reputation: 157

overriding methods in Interface java

I wrote an Interface in Java. after that I tried to implement it by overriding as shown in the code. but I get error that I have to add public before the method.

why I have to add public ? why without public it does not work ?

as the Net-Beans says : " attempting to assign weaker access privileges; was public "

the code : 

    package tryinginterface;
interface Bicycle {

    //  wheel revolutions per minute
    void changeCadence(int newValue);

    void changeGear(int newValue);

    void speedUp(int increment);

    void applyBrakes(int decrement);
}


class ACMEBicycle implements Bicycle {

    int cadence = 0;
    int speed = 0;
    int gear = 1;
    @Override 
        void changeCadence(int newValue) {
         cadence = newValue;
    }
    @Override
    void changeGear(int newValue) {
         gear = newValue;
    }
    @Override
    void speedUp(int increment) {
         speed = speed + increment;   
    }
    @Override
    void applyBrakes(int decrement) {
         speed = speed - decrement;
    }
    @Override
    void printStates() {
         System.out.println("cadence:" +
             cadence + " speed:" + 
             speed + " gear:" + gear);
    }
}

Upvotes: 4

Views: 386

Answers (3)

vishwampandya
vishwampandya

Reputation: 1187

lets suppose you have a interface Printable,which contains a method print().

interface Printable{
   int MIN=5;
   void print();
}

now because the method is declared inside interface , compiler implicitly adds public abstract before the method. like this :- interface for compiler

now as the method is been declared public , so now when you extend the method you have to add public before the method.

I think this might help you.

Upvotes: 0

Eutherpy
Eutherpy

Reputation: 4581

Because in an interface, all methods are by default public, and in a class, the default visibility of methods is "friend" - seen in the same package.

You can't narrow down the visibility when implementing a method, that's the rule.

Upvotes: 3

Xabster
Xabster

Reputation: 3720

All methods in interfaces are public.

All methods in a class without a visibility modifier are package-private.

You cannot reduce the visibility of the public methods to package-private because it violates the interface.

Upvotes: 8

Related Questions