diff --git a/java/sum/Sum.java b/java/sum/Sum.java
new file mode 100644
index 0000000..ef35486
--- /dev/null
+++ b/java/sum/Sum.java
@@ -0,0 +1,28 @@
+package sum;
+
+/**
+ * @author Nikita Doschennikov (me@fymio.us)
+ */
+public class Sum {
+
+    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 += (!builder.toString().isEmpty())
+                        ? Integer.parseInt(builder.toString())
+                        : 0;
+                    builder = new StringBuilder();
+                }
+            }
+            res += (!builder.toString().isEmpty())
+                ? Integer.parseInt(builder.toString())
+                : 0;
+        }
+        System.out.println(res);
+    }
+}
diff --git a/java/sum/SumBigDecimalHex.java b/java/sum/SumBigDecimalHex.java
new file mode 100644
index 0000000..6c50146
--- /dev/null
+++ b/java/sum/SumBigDecimalHex.java
@@ -0,0 +1,63 @@
+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();
+            int idxOfS = -1;
+            for (char c : arg.toCharArray()) {
+                if (!Character.isWhitespace(c)) {
+                    if (c == 's' || c == 'S') {
+                        idxOfS = builder.length();
+                    }
+                    builder.append(c);
+                } else {
+                    res = res.add(compute(builder.toString(), idxOfS));
+                    idxOfS = -1;
+                    builder = new StringBuilder();
+                }
+            }
+            res = res.add(compute(builder.toString(), idxOfS));
+        }
+        System.out.println(res);
+    }
+
+    static BigDecimal compute(String num, int idxOfS) {
+        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 (idxOfS != -1) {
+                idxOfS -= 2;
+                String mantissaHex = num.substring(0, idxOfS);
+                String exponentHex = num.substring(idxOfS + 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;
+    }
+}
diff --git a/java/sum/SumBigIntegerOctal.java b/java/sum/SumBigIntegerOctal.java
new file mode 100644
index 0000000..b65b35b
--- /dev/null
+++ b/java/sum/SumBigIntegerOctal.java
@@ -0,0 +1,45 @@
+package sum;
+
+import java.math.BigInteger;
+
+/**
+ * @author Nikita Doschennikov (me@fymio.us)
+ */
+public class SumBigIntegerOctal {
+
+    public static void main(String[] args) {
+        BigInteger res = new BigInteger("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 BigInteger compute(String num) {
+        BigInteger res = new BigInteger("0");
+        int numLength = num.length();
+        if (num.isEmpty()) {
+            res = res.add(BigInteger.ZERO);
+        } else if (
+            num.charAt(numLength - 1) == 'o' || num.charAt(numLength - 1) == 'O'
+        ) {
+            res = res.add(
+                new BigInteger(num.substring(0, num.length() - 1), 8)
+            );
+        } else {
+            res = res.add(new BigInteger(num));
+        }
+
+        return res;
+    }
+}
diff --git a/java/sum/SumDouble.java b/java/sum/SumDouble.java
new file mode 100644
index 0000000..57fb236
--- /dev/null
+++ b/java/sum/SumDouble.java
@@ -0,0 +1,28 @@
+package sum;
+
+/**
+ * @author Nikita Doschennikov (me@fymio.us)
+ */
+public class SumDouble {
+
+    public static void main(String[] args) {
+        double res = 0.0;
+        for (String arg : args) {
+            StringBuilder builder = new StringBuilder();
+            for (char c : arg.toCharArray()) {
+                if (!Character.isWhitespace(c)) {
+                    builder.append(c);
+                } else {
+                    res += (!builder.toString().isEmpty())
+                        ? Double.parseDouble(builder.toString())
+                        : 0;
+                    builder = new StringBuilder();
+                }
+            }
+            res += (!builder.toString().isEmpty())
+                ? Double.parseDouble(builder.toString())
+                : 0;
+        }
+        System.out.println(res);
+    }
+}
diff --git a/java/sum/package-info.java b/java/sum/package-info.java
new file mode 100644
index 0000000..d4d2abc
--- /dev/null
+++ b/java/sum/package-info.java
@@ -0,0 +1,7 @@
+/**
+ * Tests for <a href="https://www.kgeorgiy.info/courses/prog-intro/homeworks.html#sum">Sum</a> homework
+ * of <a href="https://www.kgeorgiy.info/courses/prog-intro/">Introduction to Programming</a> course.
+ *
+ * @author Georgiy Korneev (kgeorgiy@kgeorgiy.info)
+ */
+package sum;