信件柜台代码 [重复]

Question

//提示是：写一个程序让用户输入一个字符串，//然后让用户输入一个字符。程序应该计数并显示 //指定字符在字符串中出现的次数。

import java.util.Scanner;
public class LetterCounter{
Scanner keyboard = new Scanner (System.in);     //Scanner
// Declare Variables
    String userString;      // String user entered
    String userCharacter;   // Character user entered
    int StringSize;      
// Ask the user to enter a string
    System.out.println("Please Enter a String.");
    userString = keyboard.nextLine();

// Ask the user to enter a charcter
    System.out.println("Please Enter a Character.");
    userCharacter = keyboard.nextLine();

// Count and display the number of times that character appears in the
// string chosen by the user.
    int character; 
    character = Integer.parseInt(userCharacter);
    StringSize = userString.charAt(character);
}
}

由于某种原因，我无法让它工作，我只是不知道从这里去哪里。我可能需要一个 FOR-LOOP 吗？

感谢您的帮助

Answer 1

你好，看看这个

package gmit;

import java.util.Scanner;
public class LetterCounter{

    public static void main(String[] args) {
        String keyBoardChar;    

Scanner keyboard = new Scanner (System.in);     //Scanner
// Declare Variables
    String userString;      // String user entered
    char userCharacter;   // Character user entered
    int StringSize;      
// Ask the user to enter a string
    System.out.println("Please enter a string");
    userString = keyboard.nextLine();

// Ask the user to enter a charcter

    System.out.println("Please Enter a Character.");
    char kChar = keyboard.next().charAt(0);

// Count and display the number of times that character appears in the
// string chosen by the user.
    int character = 0; 
    //character = Integer.parseInt(userCharacter);
    //StringSize = userString.charAt(character);

    char[] StringToChar = userString.toCharArray();
    for(int i = 0; i < StringToChar.length - 1; i++){
        if ( StringToChar[i] == kChar){
            character++;
        }
    }
    System.out.println("character count is " + character);

} }

我使用 char kChar = keyboard.next().charAt(0);

并将 String 转换为 Char 数组，运行 for 循环遍历每个字母并检查它是否与所选字符相同。每次检查为真时，我都会在字符计数器中添加一个。

Answer 2

是的，您需要使用 for 循环。

int count = 0;
for (char ch: userString.toCharArray()) {
    if(userChar == ch) count++;
}