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;
}
}