Combinations of a String

StringCombinations.java

public class StringLib {
		
	public static void combine(String str){
		int length=str.length();
		
		StringBuffer output=new StringBuffer();
		
		combination(str,length,output,0);
	}
	
	static void combination(String str, int length, StringBuffer output, int level){
		/* show arms-length recursion style with better peformance */
		if (level==length)
			return;
		else{
			for(int i=level;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");
	}
}

/*Output:

a
ab
abc
ac
b
bc
c
*/