Interface on OOFP 2025-26

Specification and programming interface

Mon, 01 Jan 0001 00:00:00 +0000

Specification and programming interface #

Specification #

The specification of a method primarily describes the problem that the method solves (i.e. its input and expected output).

Optionally, the specification may provide information about:

the behavior of the program for invalid inputs (e.g. errors thrown by the method),

its implementation (if this has an impact on performance ),

etc.

Example.
 boolean isSolvable(int[][] grid)
Input: a 9 x 9 array of integers with numbers between 0 and 9

Output: true is this array represents a sudoku grid with a unique solution (where 0 stands for the absence of value)

Errors:

if the array’s size is not 9 x 9

if the array contains a number smaller that 0 or greater than 9

Variation. If a method has no return type or is not a pure function, then the specification may indicate the effect of the method on its environment.

Java interface

Mon, 01 Jan 0001 00:00:00 +0000

Java interface #

A Java interface is a programming interface with additional (object-oriented) features.

A Java interface is similar to a class, with the exception that the methods that it declares are (by default) not implemented.

Instead, the interface only specifies the behavior of these methods. Their implementations is found in the classes that implement the interface.

Illustration #

Example. We may declare an interface for chess pieces, as follows.