Interleavings of two strings

Given two strings str1 and str2, write a function that prints all interleavings of the given two strings. You may assume that all characters in both strings are different

Example :
Input: str1 = "AB",  str2 = "CD"
Output:
    ABCD
    ACBD
    ACDB
    CABD
    CADB
    CDAB

public class InterLeavedStrings {
 public static void main(String[] args) {
  String str1 = "abc";
  String str2 = "def";

  if (str1 != null && str1.length() != 0 && str2 != null
    && str2.length() != 0) {
   getInterLeavedStrings(str1, str2);
   getInterLeavedStrings(str2, str1);
  } else if (str1 == null || str1.length() == 0) {
   System.out.println(str2);
  } else {
   System.out.println(str1);
  }
 }

 private static void getInterLeavedStrings(String str1, String str2) {
  int m = str1.length();
  int n = str2.length();
  for (int i = 1; i < m; i++) {
   for (int j = 0; j < n; j++) {
    System.out.println(str1.substring(0, i) + str2.substring(0, j)
      + str1.substring(i, m) + str2.substring(j, n));
   }
  }
 }
}

Another variant of interleaving : Check a given string is interleaving of other two strings
 http://www.geeksforgeeks.org/archives/17750


Refer : http://www.geeksforgeeks.org/archives/17743