java的字符串统计课设.rar

7. 字符数统计(满分 35 分) 版本 1：满分 10 分 Write a method that counts the number of letters in a string using the following header: public static int countLetters (String s) Write a test program that prompts the user to enter a string and displays the number of occurrences of letters in the string. 版本 2：满分 10 分 Write a class that displays the number of occurrences of each letter in a string using histogram. The class header should be: public class Histogram extends JPanel { … } Write a test program that prompts the user to enter a string and displays a histogram of the number of occurrences of each letter in the string using Histogram class. The display is as shown as following fig