add all variants for 'Sum' task (hw2)

java/sum/SumBigDecimalHex.java

@@ -0,0 +1,57 @@
+package sum;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+
+/**
+ * @author Nikita Doschennikov (me@fymio.us)
+ */
+public class SumBigDecimalHex {
+    public static void main(String[] args) {
+        BigDecimal res = new BigDecimal("0");
+        for (String arg : args) {
+            StringBuilder builder = new StringBuilder();
+            for (char c : arg.toCharArray()) {
+                if (!Character.isWhitespace(c)) {
+                    builder.append(c);
+                } else {
+                    res = res.add(compute(builder.toString()));
+
+                    builder = new StringBuilder();
+                }
+            }
+            res = res.add(compute(builder.toString()));
+        }
+        System.out.println(res);
+    }
+
+    static BigDecimal compute(String num) {
+        BigDecimal res = BigDecimal.ZERO;
+
+        if (num == null || num.isEmpty()) {
+            return res;
+        } else if (num.startsWith("0x") || num.startsWith("0X")) {
+            num = num.toLowerCase();
+            num = num.substring(2);
+            if (num.contains("s")) {
+
+                int sIndex = num.indexOf('s');
+
+                String mantissaHex = num.substring(0, sIndex);
+                String exponentHex = num.substring(sIndex + 1);
+
+                BigInteger mantissa = new BigInteger(mantissaHex, 16);
+                BigInteger exponent = new BigInteger(exponentHex, 16);
+
+                res = res.add(new BigDecimal(mantissa).scaleByPowerOfTen(exponent.negate().intValueExact()));
+            } else {
+                res = res.add(new BigDecimal(new BigInteger(num, 16)));
+            }
+        } else {
+            res = new BigDecimal(num);
+        }
+
+        return res;
+    }
+
+}