组合

import java.util.ArrayList;import java.util.List;public class Combination {char[] chars={'a','b','c','d'};List<Character> list=new ArrayList<Character>();public void getCombination(char[] chars,List<Character> list,int i){if(i==chars.length){for(int j=0;j<list.size();j++){System.out.print(list.get(j)+"  ");}System.out.println();}else{list.add(chars[i]);getCombination(chars,list,i+1);boolean re=list.remove((Object)chars[i]);if(re){getCombination(chars,list,i+1);}}}public static void main(String[] args) {Combination com=new Combination();com.getCombination(com.chars, com.list, 0);}}

运行结果：