Find Combinations of letters

This solution gives all the combinations of letters of a word.

For example if the input is ABC, the output will be:

A
B
C
AB
AC
BC
ABC

public class StringPermutation {  
  
    String input;   //input String
    StringBuffer output;  //Holds the output
    
    /*
     * Generates combinations by applying the 
     * concept of recursion
     */
    private void nextCombination(int position, int remainder) 
    {     
        output.append(input.charAt(position));  
        
        if (remainder == 1) {       
          System.out.println(output);     
        } else {       
          for (int i = position + 1; i + remainder - 1 <= input.length(); i++)         
            nextCombination(i, remainder - 1);     
        }     
        
        output.deleteCharAt(output.length() - 1); 
    }    
    
    public void generateCombinations(String input) 
    {     
          output = new StringBuffer();     
          this.input = input;
          int inputStrLength = input.length();
          
          for (int i = 1; i <= inputStrLength; i++)       
              for (int j = 0; j + i <= inputStrLength; j++)         
                  nextCombination(j, i);   
    } 
  
    /** 
     * @param args 
     */  
    public static void main(String[] args) {           
        new StringPermutation().generateCombinations("ABC");  
  
    }  
}