update

public/courses/prog-intro/homeworks/sum/sumhex/SumHex.java

@@ -0,0 +1,38 @@
+// SumHex.java
+
+public class SumHex {
+
+    public static void main(String[] args) {
+        int 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);
+                    number = new StringBuilder();
+                }
+            }
+
+            sum += parseNumber(number);
+        }
+
+        System.out.println(sum);
+    }
+
+    static long parseNumber(StringBuilder number) {
+        if (!number.isEmpty()) {
+            String numberString = number.toString();
+            if (
+                numberString.startsWith("0x") || numberString.startsWith("0X")
+            ) {
+                return Long.parseLong(numberString.substring(2), 16);
+            } else {
+                return Integer.parseInt(numberString);
+            }
+        } else {
+            return 0;
+        }
+    }
+}