392. Is Subsequence

class Solution {
    public boolean isSubsequence(String s, String t) {
        int l1 = s.length();
        int l2 = t.length();
        if (l1 == 0 )
            return true;
        boolean res = true;
        int p = 0;
        for (int i = 0; i < l1; i++) {
//            每次从p的位置往后找字符
            p = t.indexOf(s.charAt(i),p);
            if (p == -1)
                return false;
            p++;
        }

        return res;
    }
}

主要是学到了indexof 的方法