Thread: Interface

Hello,i have two beginner's questions.
1- Can an interface have some fields(i mean variables)?Or the only thing it contains are prototypes of methods?
2-When we want a method to receive no arguments at all how do we state it?I tried to write void,but the compiler says <identifier> expected
Here is the code

package airplane;
 
public interface AirplaneInterface {
    boolean taxi(String taxiway);
    boolean takeoff(String runway);
    boolean approach(String runway);
    boolean land(String runway);
    void setEngines(boolean on);
    boolean changeAltitude(int factor);
    int getAltitude(void);
}

Originally Posted by Samaras

Hello,i have two beginner's questions.
1- Can an interface have some fields(i mean variables)?Or the only thing it contains are prototypes of methods?
2-When we want a method to receive no arguments at all how do we state it?I tried to write void,but the compiler says <identifier> expected

1- What does the doc say about an interface? Read this page.
2- When you declare a method with no arguments in a normal class do you write void in the parentheses? Try treating the method declaration like a method declaration in any other class.

1- I am reading the tutorial you linked me,however i do not have reached the point you posted.But there lies this:
In the Java programming language, an interface is a reference type, similar to a class, that can contain only constants, method signatures, and nested types.

2 - I am new in JAVA and i did not think about it until i got to deal with it.Ok,thanks