Java requires implementing default method

Question

I have Base interface:

public interface Doable {
    void doAction(String str);
}

I have extending interface:

public interface DoubleDoable extends Doable{
  @Override 
  default void doAction(String str) {
      doOnce();
      doOnce();
  }

  void doOnce();
}

And I have an implementation:

public class Action implements DoubleDoable {
    public void doOnce() {
      System.out.println(123);
    }
}

However, it is not compiled, as: Error:(10, 8) java: Action is not abstract and does not override abstract method doAction(java.lang.String) in Doable

Am I doing something wrong?

I assume your method is not called do as this is a reserved keyword in Java. — Alexandre Dupriez
– Alexandre Dupriez, Commented Nov 11, 2017 at 11:29
once you change the name do to something else you'll be fine. — Ousmane D.
– Ousmane D., Commented Nov 11, 2017 at 11:30
Compiles fine in Java 8. Just need to use something else than do for the method name. — Robby Cornelissen
– Robby Cornelissen, Commented Nov 11, 2017 at 11:31
1.8.0_144, but I doubt that it matters. If you're actually using that compiler, then you're probably compiling with a -source or -target flag set to 1.7 or lower. — Robby Cornelissen
– Robby Cornelissen, Commented Nov 11, 2017 at 11:41
@RobbyCornelissen, this was the issue - one of the modules had 1.6 source for some reason. Now it is OK. If you make it into separate answer, I will mark it as correct. Thank you — Rahul
– Rahul, Commented Nov 11, 2017 at 11:48

Robby Cornelissen · Accepted Answer · 2017-11-11 12:01:34Z

2

If you're using a Java 8 compiler, the only way that your code can cause that compilation error is if the value of the -source flag that is passed to the compiler is set to 1.7 or lower.

Something like:

javac -source 1.7 ...

If you're using maven, the property setting below will have the same effect.

<maven.compiler.source>1.7</maven.compiler.source>

edited Nov 11, 2017 at 12:01

answered Nov 11, 2017 at 11:52

Robby Cornelissen

98.6k23 gold badges154 silver badges180 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Pshemo · Accepted Answer · 2017-11-11 11:38:36Z

0

You can't call method do because it's java reserved word. All list of Java keywords you can find here.

edited Nov 11, 2017 at 11:38

Pshemo

125k25 gold badges194 silver badges280 bronze badges

answered Nov 11, 2017 at 11:30

icarumbas

1,8343 gold badges19 silver badges32 bronze badges

3 Comments

icarumbas Over a year ago

@Aominè changed. I mean give it name. Changed.

Rahul Over a year ago

This was just for example, bad for this

Digvijaysinh Gohil Over a year ago

It means that Java's reserved keywords can't be used for naming methods or variables

Collectives™ on Stack Overflow

Java requires implementing default method

2 Answers 2

Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related