递归实现字符或单词在字符串中是否存在

import java.util.*;
public class Dictionary {
static String dictionary = new String("abskljlsajdfklajflkdhalkldfjalhflas");
public static void main(String []args){
Scanner in = new Scanner(System.in);
String input = in.nextLine().trim();
System.out.println(indexSearch(input));
}
static boolean indexSearch(String str){
boolean flag = true ;
if(str.length()>dictionary.length()){
return false;
}
for(int i = 0 ;i < str.length() ;i++){
if(str.charAt(i)!= dictionary.charAt(i)){
flag = false ;
break;
}
}
if (flag == true){
return true;
}
else{
dictionary = dictionary.substring(1,dictionary.length());
System.out.println(dictionary);
return indexSearch(str);
}
}
}