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Java Programming - Declarations and Access Control - Discussion

Discussion Forum : Declarations and Access Control - General Questions (Q.No. 9)
Declarations and Access Control
9.
Which three are valid method signatures in an interface?
  1. private int getArea();
  2. public float getVol(float x);
  3. public void main(String [] args);
  4. public static void main(String [] args);
  5. boolean setFlag(Boolean [] test);
1 and 2
2, 3 and 5
3, 4, and 5
2 and 4
Answer: Option
Explanation:

(2), (3), and (5). These are all valid interface method signatures.

(1), is incorrect because an interface method must be public; if it is not explicitly declared public it will be made public implicitly. (4) is incorrect because interface methods cannot be static.

Discussion:
14 comments Page 2 of 2.
Suganthisakthivel said:   8 years ago
Why is the Boolean type method correct? I think the interface methods all have a public type but the 5 have Boolean, I want a full explanation.
(1)
Anonymous said:   7 years ago
@Suganthisakthivel.

Boolean is the return type of the method, not the access specifier.

The public is an access specifier and members of the interface should be public. If access specifier is not mentioned explicitly, it is considered as public here.

In the 5th method, no access specifier is mentioned explicitly, and since it is a method declared in an interface, the access specifier will default to 'public'.
Saif Ali said:   7 years ago
Yes, you can use public static void main(string ar[])
in the interface but it only works as a starting point of that particular interface.
Not as a class psvm both are different.
(1)
Harshal said:   7 years ago
With java 9 even private methods are allowed in interface.
(2)
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