Introduction to Java Programming编程题9.4<求某个字符的出现次数>

由于Java没有直接从Scanner类获取char字符的方法，所以只能用String接收字符串后通过charAt()将最后一个字符赋值给char类型。然后通过deleteChar(String str)行数将String最后一个字符删除。

/*
Enter the string: Prelude In Daydream.o
Character 'o' in "Prelude In Daydream." occurs: 0 time.
Enter the string: I never want to say you unhappy.a
Character 'a' in "I never want to say you unhappy." occurs: 3 times.
 */

import java.util.Scanner;

public class CountCharOccurs {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        System.out.print("Enter the string: ");
        String str = input.nextLine();
        char ch = str.charAt(str.length() - 1);
        str = deleteChar(str);

        int count = count(str, ch);
        System.out.println("Character '" + ch + "'" + " in \"" + str + "\"" +
                " occurs: " + count + ((count > 1) ? " times." : " time."));
    }

    public static String deleteChar(String str) {
        StringBuilder stringBuilder = new StringBuilder(str);
        stringBuilder.deleteCharAt(str.length() - 1);
        return stringBuilder.toString();
    }

    public static int count(String str, char a) {
        int count = 0;
        for (int i = 0; i < str.length(); i++) {
            if (a == str.charAt(i))
                count++;
        }

        return count;
    }
}