java - 不兼容的类型 String 和 Char

Question

我不确定为什么会收到此错误。我认为代码总体来说还可以，尽管我确信有比使用所有 else if 更短的方法。问题是它说不兼容的类型，我真的不知道如何解决这个问题。任何帮助，将不胜感激。

import java.util.Scanner;
public class MissionImpossible
{
    public static void main(String [] args){
        String lineOne,  R2D2 = "";

       Scanner in = new Scanner(System.in);
       System.out.println("Please enter a word so I can see how many vowels it has.");

       int count = 0;

       lineOne = in.nextLine();

       int word = lineOne.length();

       for (int i = word -1; i>= 0; i--) 
        {
            R2D2= lineOne.charAt(i);

            if (R2D2== 'a'|| R2D2=='A')
            count++;
            else if (R2D2=='e'||R2D2=='E')
            count++;
            else if (R2D2=='o'|| R2D2=='O')
            count++;
            else if (R2D2=='u'||R2D2=='U')
            count++;
            else if (R2D2=='y'||R2D2=='Y')
            count++;

    }
    System.out.println(count);
          }
           }

Answer 1

char 不是 String。将 R2D2 声明为 char

char R2D2 = '';

要检查元音，请使用如下方法，并在 for 循环中重用此方法并计数元音出现次数:

static boolean isVowel(char ch) {
    ch = Character.toLowerCase(ch);
    if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
        return true;
    }
    return false;
 }