Testing OSGi components - JUnit in Action - page 313

Listing 16.1 CalculatorService interface

[...]
public interface CalculatorService {

public double [] parseUserInput(String str)
throws NumberFormatException;

B

C

public double add( double ... numbers);

D

public double multiply( double ... numbers);

E

public void printResult( double result);
}
The interface defines the four methods we want to implement in our service. The first
one B parses a line of user input. The user is supposed to input several numbers sep-
arated by spaces, and this method parses the input as numbers. The add method C
sums all the given numbers and returns the result. There is also a multiply method
D , which multiplies numbers and returns the result. The printResult method E
prints a given result number.
As we already discussed, every OSG i service exposes a certain interface to other ser-
vices. Your services must provide an interface and implement it.
Listing 16.2 contains the implementation of the interface in listing 16.1.

Listing 16.2 Implementation of CalculatorService interface

[...]
public class CalculatorImpl implements CalculatorService {

public double add(double... numbers) {
double result = 0;
for ( double number:numbers)
result+=number;
return result;
}

public double multiply( double ... numbers) {
double result = 1;
for ( double number:numbers)
result*=number;
return result;
}

public double [] parseUserInput(String str)
throws NumberFormatException {
String[] numbers = str.split(" ");
doubl e[] result = new double [numbers.length];
for (int i=0;i<numbers.length;i++) {
result[i] = Double.parseDouble(numbers[i]);
}
return result;
}