字符串中的java字符

Question

所以我的问题是我需要让用户输入string。然后他们将输入一个他们想要计算的字符。所以程序应该是count how many times the character他们输入的字符串会出现，这是我的问题。如果有人能给我一些有关如何执行此操作的信息，将不胜感激。

import java.util.Scanner;
public class LetterCounter {

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

    System.out.println("please enter a word");//get the word from the user
    String word= keyboard.nextLine();
    System.out.println("Enter a character");//Ask the user to enter the character they wan counted in the string
    String character= keyboard.nextLine();

}

}

Answer 1

这是取自 this 之前提出的问题的解决方案，并经过编辑以更好地适应您的情况。

1. 要么让用户输入一个字符，要么从 他们使用character.chatAt(0) 输入的字符串。
2. 使用word.length 计算字符串的长度

3. 创建一个 for 循环并使用word.charAt() 计算您的角色出现的次数。

   System.out.println("please enter a word");//get the word from the user
   String word= keyboard.nextLine();
   System.out.println("Enter a character");//Ask the user to enter the character they want counted in the string
   String character = keyboard.nextLine();
   char myChar = character.charAt(0);
   
   int charCount = 0;
   for (int i = 1; i < word.length();i++)
   {
       if (word.charAt(i) == myChar)
       {
           charCount++;
       }
   }
   
   System.out.printf("It appears %d times",charCount);
   

Answer 2

应该这样做。它的作用是获取要查看的字符串，获取要查看的字符，遍历字符串以查找匹配项，计算匹配项的数量，然后返回信息。有更优雅的方法可以做到这一点（例如，使用正则表达式匹配器也可以）。

@SuppressWarnings("resource") Scanner scanner = new Scanner(System.in);

System.out.print("Enter a string:\t");
String word = scanner.nextLine();

System.out.print("Enter a character:\t");
String character = scanner.nextLine();

char charVar = 0;
if (character.length() > 1) {
    System.err.println("Please input only one character.");
} else {
    charVar = character.charAt(0);
}

int count = 0;
for (char x : word.toCharArray()) {
    if (x == charVar) {
        count++;
    }
}

System.out.println("Character " + charVar + " appears " + count + (count == 1 ? " time" : " times"));