add all variants for 'Sum' task (hw2)

java/sum/SumHex.java

@@ -0,0 +1,37 @@
+package sum;
+
+/**
+ * @author Nikita Doschennikov (me@fymio.us)
+ */
+public class SumHex {
+    public static void main(String[] args) {
+        int res = 0;
+        for (String arg : args) {
+            StringBuilder builder = new StringBuilder();
+            for (char c : arg.toCharArray()) {
+                if (!Character.isWhitespace(c)) {
+                    builder.append(c);
+                } else {
+                    res += compute(builder.toString());
+
+                    builder = new StringBuilder();
+                }
+            }
+            res += compute(builder.toString());
+        }
+        System.out.println(res);
+    }
+
+    static int compute(String num) {
+        int res = 0;
+        if (num.isEmpty()) {
+            res += 0;
+        } else if (num.startsWith("0x") || num.startsWith("0X")) {
+            res += Long.decode(num);
+        } else {
+            res += Integer.parseInt(num);
+        }
+
+        return res;
+    }
+}