Data commit

Task/Commatizing-numbers/Java/commatizing-numbers.java

@@ -0,0 +1,40 @@
+import java.io.File;
+import java.util.*;
+import java.util.regex.*;
+
+public class CommatizingNumbers {
+
+    public static void main(String[] args) throws Exception {
+        commatize("pi=3.14159265358979323846264338327950288419716939937510582"
+                + "097494459231", 6, 5, " ");
+
+        commatize("The author has two Z$100000000000000 Zimbabwe notes (100 "
+                + "trillion).", 0, 3, ".");
+
+        try (Scanner sc = new Scanner(new File("input.txt"))) {
+            while(sc.hasNext())
+                commatize(sc.nextLine());
+        }
+    }
+
+    static void commatize(String s) {
+        commatize(s, 0, 3, ",");
+    }
+
+    static void commatize(String s, int start, int step, String ins) {
+        if (start < 0 || start > s.length() || step < 1 || step > s.length())
+            return;
+
+        Matcher m = Pattern.compile("([1-9][0-9]*)").matcher(s.substring(start));
+        StringBuffer result = new StringBuffer(s.substring(0, start));
+
+        if (m.find()) {
+            StringBuilder sb = new StringBuilder(m.group(1)).reverse();
+            for (int i = step; i < sb.length(); i += step)
+                sb.insert(i++, ins);
+            m.appendReplacement(result, sb.reverse().toString());
+        }
+
+        System.out.println(m.appendTail(result));
+    }
+}