java - 需要帮助根据用户输入列出字符的频率

Question

我当前的代码列出了字母数组的频率，我想知道是否有一种方法可以合并数字和用户可用的所有标点符号。 (即 ASCII 文本)我很感激任何帮助!

import java.util.Scanner;

public class JavaProgram
{
public static void main(String args[])
{
   Scanner scan = new Scanner(System.in);
    int i = 0; 
    int j = 0; 
    int k = 0; 
    String str;
    char c, ch;


    System.out.print("Enter a String : ");
    str=scan.nextLine();

    i=str.length();
    for(c='A'; c<='z'; c++)
    {
        k=0;
        for(j=0; j<i; j++)
        {
            ch = str.charAt(j);
            if(ch == c)
            {
                k++;
            }
        }
        if(k>0)
        {
            System.out.println( c + "  "  + k );
        }



}
}
}

input
Enter a String : jhdvaevaecvieabvuae[;;;/'[298734327
output
[  2
a  4
b  1
c  1
d  1
e  4
h  1
i  1
j  1
u  1
v  4

此外，此代码已准备好区分大小写。

Answer 1

您可以使用以下步骤。创建一个容量为 128(ascii 字符集大小)的频率数组。将频率的所有元素初始化为 0。现在扫描输入字符串的每个字符，并将频率数组中的频率加 1。数组的索引可以通过将当前字符转换为其整数表示来计算。为了供您引用，您可以查看下面提供的代码。

public String computeFrequency(String input) {
    int []frequecy = new int[128]; // each element of array represent frequency of some character indexed by character's ascii code
    for(char ch: input.toCharArray()) {
        int intCurrentChar = (int) ch;  // get ascii code of current character. It can be obtained by casting character to integer in java.
        frequecy[intCurrentChar]++; // increase the frequency of current character
    }

    // collect all non zero frequency to string
    StringBuilder sbr = new StringBuilder();
    for(int frequencyIndex = 0; frequencyIndex <128; frequencyIndex++) {
        if( frequecy[frequencyIndex]>0) {
            char ch = (char) frequencyIndex; // get ascii character from ascii code. It can be obtained by casting integer to character in java.
            sbr.append(ch).append(" ").append(System.lineSeparator());
        }
    }

    return sbr.toString();  
}