Initial data commit

Task/Middle-three-digits/Java/middle-three-digits.java

@@ -0,0 +1,27 @@
+public class MiddleThreeDigits {
+
+    public static void main(String[] args) {
+        final long[] passing = {123, 12345, 1234567, 987654321, 10001, -10001,
+            -123, -100, 100, -12345, Long.MIN_VALUE, Long.MAX_VALUE};
+
+        final int[] failing = {1, 2, -1, -10, 2002, -2002, 0, Integer.MIN_VALUE,
+            Integer.MAX_VALUE};
+
+        for (long n : passing)
+            System.out.printf("middleThreeDigits(%s): %s\n", n, middleThreeDigits(n));
+
+        for (int n : failing)
+            System.out.printf("middleThreeDigits(%s): %s\n", n, middleThreeDigits(n));
+    }
+
+    public static <T> String middleThreeDigits(T n) {
+        String s = String.valueOf(n);
+        if (s.charAt(0) == '-')
+            s = s.substring(1);
+        int len = s.length();
+        if (len < 3 || len % 2 == 0)
+            return "Need odd and >= 3 digits";
+        int mid = len / 2;
+        return s.substring(mid - 1, mid + 2);
+    }
+}