Use java to determine the position where a character first appears

import java.util.Collections; import java.util.LinkedList; import java.util.List; import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String s = sc.nextLine(); String[] a = { "a", "e", "i", "o", "u" }; List list = new LinkedList(); int i; boolean flag = false; for (i = 0; i < a.length; i++) { if (s.indexOf(a[i]) != -1) {//s.indexOf(" ")返回元素的下标 list.add(s.indexOf(a[i]) + 1); flag = true; } } if (flag == false) { System.out.println("0"); } else { Collections.sort(list);//要返回元音字母首次出现的位置，所以先排序 System.out.print(list.get(0));//在输出第一个元素就可以 } sc.close(); } }