java-输入一个字符串，输出该字符串中字符的所有组合。举个例子，如果输入abc，它的组合有a、b、c、ab、ac、bc、abc

import java.util.ArrayList;import java.util.List;public class Combination {public static void main(String[] args) {char[] a = { 'a', 'b', 'c' };List<Character> list = new ArrayList<Character>();for (int i = 1, len = a.length; i <= len; i++) {combine(a, 0, i, list);}}        /* * we can also use Stack like this:    stack.push(a[begin]);combination(a,begin+1,number-1,stack);stack.pop();combination(a,begin+1,number,stack); */public static void combine(char[] a, int begin, int resultLength,List<Character> list) {if (resultLength == 0) {System.out.println(list.toString());return;}if (begin == a.length){return;}list.add(a[begin]);combine(a, begin + 1, resultLength - 1, list);list.remove((Character) a[begin]);combine(a, begin + 1, resultLength, list);}}

the idea is fromhttp://zhedahht.blog.163.com/blog/static/2541117420114172812217/