题解 | #统计字符#

public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        String s1 = sc.nextLine();
        char a1[] = s1.toCharArray();
        int charNum = 0; int spaceNum = 0;
        int dightNum = 0; int elseNum = 0;
        for(int i=0;i<a1.length;i++){
            if(Character.isLetter(a1[i])){
                ++charNum;
            }
            else if(Character.isDigit(a1[i])){
                ++dightNum;
            }
            else if(a1[i]==32){
                ++spaceNum;
            }
            else{
                ++elseNum;
            }

        }
        System.out.println(charNum);System.out.println(spaceNum);
        System.out.println(dightNum);System.out.println(elseNum);
        }