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package resources;
import javax.ws.rs.Consumes;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
/**
* Calculator resource exposed at '/calculator' path
*/
@Path("/calculator")
public class CalculatorResource {
/**
* Method handling HTTP POST requests. The calculated answer to the expression will be sent to the client as
* plain/text.
* @param expression the expression to be solved as plain/text.
* @return solution to the expression as plain/text or -1 on error
*/
@POST
@Consumes(MediaType.TEXT_PLAIN)
@Produces(MediaType.TEXT_PLAIN)
public int calculate(String expression){
// Removes all whitespaces
String expressionTrimmed = expression.replaceAll("\\s+","");
int result = -1;
/*
* .matches use regex expression to decide if a String matches a given pattern.
* [0-9]+[+][0-9]+ explained:
* [0-9]+: a number from 0-9 one or more times. For example 1, 12 and 123.
* [+]: the operator + one time.
* The total regex expression accepts for example:
* 12+34,
* 1+2,
* 10000+1000
*/
if(expressionTrimmed.matches("[0-9]+[+][0-9]+")) result = sum(expressionTrimmed);
else if(expressionTrimmed.matches("[0-9]+[-][0-9]+")) result = subtraction(expressionTrimmed);
return result;
}
/**
* Method used to calculate a sum expression.
* @param expression the equation to be calculated as a String
* @return the answer as an int
*/
public int sum(String expression){
String[] split = expression.split("[+]");
int number1 = Integer.parseInt(split[0]);
int number2 = Integer.parseInt(split[1]);
return number1 + number2;
}
/**
* Method used to calculate a subtraction expression.
* @param expression the expression to be calculated as a String
* @return the answer as an int
*/
public int subtraction(String expression){
String[] split = expression.split("[-]");
int number1 = Integer.parseInt(split[0]);
int number2 = Integer.parseInt(split[1]);
return number1 - number2;
}
}