update

public/courses/prog-intro/homeworks/sum/sumdouble/SumDouble.java

@@ -0,0 +1,27 @@
+// SumDouble.java
+
+public class SumDouble {
+
+    public static void main(String[] args) {
+        double sum = 0;
+        for (String argument : args) {
+            StringBuilder number = new StringBuilder();
+            for (char c : argument.toCharArray()) {
+                if (!Character.isWhitespace(c)) {
+                    number.append(c);
+                } else {
+                    sum += parseNumber(number); // method call
+                    number = new StringBuilder();
+                }
+            }
+
+            sum += parseNumber(number); // method call
+        }
+
+        System.out.println(sum);
+    }
+
+    static double parseNumber(StringBuilder number) {
+        return number.isEmpty() ? 0.0 : Double.parseDouble(number.toString());
+    }
+}