combinations in java

1private void helper(List<int[]> combinations, int data[], int start, int end, int index) {    
2  if (index == data.length) {        
3    int[] combination = data.clone();        
4    combinations.add(combination);    
5  } 
6  else if (start <= end) {        
7    data[index] = start;        
8    helper(combinations, data, start + 1, end, index + 1);        
9    helper(combinations, data, start + 1, end, index);    
10  }
11}