如何计算一次输入的字符串中的大写元音和小写元音？

Question

I have created a program in Java to count lowercase vowels, but I'm not able to count uppercase vowels.

public static void main(String[] args) {
    Scanner input = new Scanner (System.in);
    //String input = new String(input.toUpperCase(0));
    System.out.print("Enter tha Letter: ");
    char x = input.next().charAt(0);
    if(x=='a' || x=='e' || x=='i' || x=='o' || x=='u'){
        System.out.println("Vowel");
    }else{
        System.out.println("Consonant");
    }
}

Answer 1

You could have a string containing your vowels and then check whether it contains the first char of the input:

Scanner input = new Scanner(System.in);
String vowels = "aeiouAEIOU";

System.out.print("Enter tha Letter: ");
char x = input.next().charAt(0);

if(vowels.contains(Character.toString(x))){
    System.out.println("Vowel");
}else{
    System.out.println("Consonant");
}

input.close();

Alternatively, reduce vowels to "aeiou" and lowercase the input character using Character.toString(x) . But I personally like the other way better.

Answer 2

You can create a final string of aeiouAEIOU and search and check if its a vowel

Since aeiouAEIOU has a fixed length the time complexity to check for a vowel is O(1)

public static void main(String[] args) {
        Scanner input = new Scanner (System.in);
        //String input = new String(input.toUpperCase(0));
        System.out.print("Enter tha Letter: ");
        String x = input.next().substring(0, 1);

        final String vowels = "aeiouAEIOU";
        if(vowels.contains(x)){
            System.out.println("Vowel");
        }else{
            System.out.println("Consonant");
        }
    }

Answer 3

You can simply append the conditions for Uppercase vowels in your existing if condition:

if(x=='a' || x=='e' || x=='i' || x=='o' || x=='u' || x=='A' || x=='E' || x=='I' || x=='O' || x=='U'){
        System.out.println("Vowel");
}

Answer 4

I have created a program in Java to count lowercase vowels, but I'm not able to count uppercase vowels.

public static void main(String[] args) {
    Scanner input = new Scanner (System.in);
    //String input = new String(input.toUpperCase(0));
    System.out.print("Enter tha Letter: ");
    char x = input.next().charAt(0);
    if(x=='a' || x=='e' || x=='i' || x=='o' || x=='u'){
        System.out.println("Vowel");
    }else{
        System.out.println("Consonant");
    }
}