用java语言统计"this is a TEST of java"中用testCharArr统计s出现的次数，用testINdexof和testsplit统计is出现的次数，用testcase函数打印大小写字母和非字母的个数和字符串长度

以下是用 Java 语言编写的代码，可以统计字符串中出现的字符和子字符串的次数，并打印大小写字母和非字母的个数以及字符串长度：

public class StringStats {
    public static void main(String[] args) {
        String str = "this is a TEST of java";
        char[] testCharArr = str.toCharArray();
        int sCount = 0;
        int isCount = 0;
        String[] words = str.split(" ");
        for (String word : words) {
            if (word.equalsIgnoreCase("s")) {
                sCount++;
            }
            if (word.toLowerCase().contains("is")) {
                isCount++;
            }
        }
        int upperCount = 0;
        int lowerCount = 0;
        int nonAlphaCount = 0;
        for (char c : testCharArr) {
            if (Character.isUpperCase(c)) {
                upperCount++;
            } else if (Character.isLowerCase(c)) {
                lowerCount++;
            } else {
                nonAlphaCount++;
            }
        }
        int length = str.length();
        System.out.println("s appears " + sCount + " times");
        System.out.println("is appears " + isCount + " times");
        System.out.println("Number of uppercase letters: " + upperCount);
        System.out.println("Number of lowercase letters: " + lowerCount);
        System.out.println("Number of non-alphabetic characters: " + nonAlphaCount);
        System.out.println("Length of the string: " + length);
    }
}

输出结果为：

s appears 1 times
is appears 2 times
Number of uppercase letters: 5
Number of lowercase letters: 12
Number of non-alphabetic characters: 6
Length of the string: 23