Invoking static methods

If a method or field is declared static, you access it by using the class name rather than a reference to a particular instance of the class. Therefore instead of writing

  Car c = new Car("New York", 89.7); 
  double maximumLegalSpeed = c.getSpeedLimit();

you just write

  double maximumLegalSpeed = Car.getSpeedLimit();

There does not even have to be an instance of a class in order to invoke a static method in the class.

Static methods may not call non-static methods or members of the same class directly. Rather they must specify which instance of the class they are referring to. Trying to call a non-static method or member is a very common compile time error. The specific error message generated by the javac compiler will look something like this

Error:    Can't make static reference to method void floorIt() in class Car. 

Of course the names and signature will be changed to match the specific method and class.

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Copyright 1998, 1999, 2003 Elliotte Rusty Harold
Last Modified September 30, 2003