Print number of dots recursion

Write a program to print number of dots in ascending sequence of integers beginning from 1, each followed by dots as many as the preceding integer.

printDots(1) = 1.

printDots(2) = 1.2..

printDots(3) = 1.2..3…
printDots(4) = 1.2..3…4….

public class PrintDots {

 public static String getPrintDots(int n) {
  if (n < 1)
   throw new IllegalArgumentException("input should greater than 0");
  return print(1, n);
 }

 private static String print(int k, int n) {
  if (k > n)
   return "";
  return k + printDotKTimes(k) + print(++k, n);
 }

 private static String printDotKTimes(int k) {
  if (k == 0)
   return "";
  return "." + printDotKTimes(--k);
 }

}

Following is the junit test case.

import static org.junit.Assert.assertEquals;

import org.junit.Test;

public class PrintDotsTest {

 @Test
 public void test1() {
  assertEquals(PrintDots.getPrintDots(1), "1.");
  assertEquals(PrintDots.getPrintDots(2), "1.2..");
  assertEquals(PrintDots.getPrintDots(3), "1.2..3...");
  assertEquals(PrintDots.getPrintDots(4), "1.2..3...4....");
  assertEquals(PrintDots.getPrintDots(5), "1.2..3...4....5.....");
 }
 
 @Test(expected=IllegalArgumentException.class)
 public void test2() {
  PrintDots.getPrintDots(0);
 }
}