字符统计-Java

输入一行文本，统计26个大写字母各自出现的次数。

MYNAMEISTZY

import java.util.Scanner;
 
public class zifutongiji {
 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[] charnum = new int[26];
         
        String str = sc.nextLine();
        str = str.trim();
        for (int i = 0; i < str.length(); i++) {
            char c = str.charAt(i);
            int ascii = (int) c;
            if (ascii >= 65 && ascii <= 90) {
                int index = ascii - (int) 'A';
                charnum[index] = charnum[index] + 1;
            }
        }
        for (int i = 0; i < charnum.length; i++) {

            System.out.println( (char) (i + 'A') + ":" + charnum[i] );
        }
 
    }
 
}