Combinations in a String

public class StringLib {

    public static void combine(String str){
        int length=str.length();

        StringBuffer output=new StringBuffer(length);

        combination(str,length,output,0);
    }

    static void combination(String str, int length, StringBuffer output, int src){
        /* show arms-length recursion style with better peformance */
        if (src==length)
            return;
        else{
            for(int i=src;i<length;i++){
                output.append(str.charAt(i));
                System.out.println(output.toString());
                //if (i<length-1)
                combination(str,length,output,i+1);
                output.deleteCharAt(output.length()-1);
            }
        }
    }


    public static void main(String[] args){
        combine("abc");
    }
}