1.写一个处理字符串的类，包含以下类方法：将字符串里大写字符变小写，小写字符变大写；在字符串中寻找子串的个数和分别出现的位置；将字符串转化为数字，并自动忽略非数字字符；找出两个字符串中相同字符的个数.-1. Write a string handling class that contains the following class method: a string in uppercase characters to lowercase, uppercase becomes lowercase characters　to find the number and position of the substring, respectively, appear in the string　convert a string digital and automatically ignore non-numeric characters　to find the same number of characters in the two strings.