统计字符串课程设计

7.字符数统计(满分50分)版本1：满分15分Writeamethodthatcountsthenumberoflettersinastringusingthefollowingheader:publicstaticintcountLetters(Strings)Writeatestprogramthatpromptstheusertoenterastringanddisplaysthenumberofoccurrencesoflettersinthestring.版本2：满分20分Writeaclassthatdisplaysthenu