获取一个字符串的所有子串

获取一个字符串的所有子串

import java.util.HashSet;import java.util.Iterator;import java.util.List;import java.util.Set;public class StringSplit {    private static Set<String> aa  = new HashSet<String>();//存贮结果    public static void main(String[] args) {        String a = "abcdefgh";        new StringSplit().split(a);        Iterator<String> iterator = aa.iterator();        while (iterator.hasNext()) {            String type = (String) iterator.next();            System.out.println(type);        }    }    public List<String> split(String a){        String sub1 = "1";        String sub2 = "2";        if (a.length()==1) {            //字符串长度为1不需要在进行切割            aa.add(a);//输入长度唯一时直接添加进set        }else{            for(int i =1;i<a.length();i++){                sub1 = a.substring(i);                sub2 = a.substring(0,i);                aa.add(sub1);                aa.add(sub2);                split(sub1);//切割的两个字符串进行递归                split(sub2);//同上            }        }        return null;    }}