MOre fixes to calc

src/main/java/resources/CalculatorResource.java

@@ -53,10 +53,11 @@ public class CalculatorResource {
     public int sum(String expression){
         String[] split = expression.split("[+]");
         int length = len(split);
+        int sum = 0;
 
         for(int i = 0; i<length; i++){
             int number = Integer.parseInt(split[i]);
-            int sum += number;
+            sum += number;
         }
         return sum;
     }
@@ -69,10 +70,11 @@ public class CalculatorResource {
     public int subtraction(String expression){
         String[] split = expression.split("[-]");
         int length = len(split);
+        int result = 0;
         
         for(int i = 0; i<length; i++){
             int number = Integer.parseInt(split[i]);
-            int result -= number;
+            result -= number;
         }
         return result;
     }
@@ -80,10 +82,11 @@ public class CalculatorResource {
     public int multiplication(String expression){
         String[] split = expression.split("[*]");
         int length = len(split);
+        int result = 0;
 
         for(int i = 0; i<length; i++){
             int number = Integer.parseInt(split[i]);
-            int result *= number;
+            result *= number;
         }
         return result;
     }
@@ -91,10 +94,11 @@ public class CalculatorResource {
     public int division(String expression){
         String[] split = expression.split("[/]");
         int length = len(split);
+        int result = 0;
 
         for(int i = 0; i<length; i++){
             int number = Integer.parseInt(split[i]);
-            int result /= number;
+            result /= number;
         }
         return result;
     }