java - 如何解决无输出问题-使用while-？

Question

我尝试读取“Mi4”的每个字符如果是字母，则将其放入变量“大写”中如果是数字，则将其放入变量“num”中没有错误，也没有输出“

public static void main(String[] args) {
    String capital = "";
    int num = 1;
    String sentence = "Mi4";
    int senLength = sentence.length();
    int i = 0;
    while (i < senLength) {
        String senStr = sentence.substring(i, i + 1);
        char senChar = senStr.charAt(i);
        if (senChar >= 'A' && senChar <= 'Z') {
            capital = senStr;
        } else if (senChar >= 'a' && senChar <= 'z') {
            capital = capital + senStr;
        } else if (senChar >= '2' && senChar <= '9') {
            num = Integer.parseInt(senStr);
        }
        i++;
        sentence = sentence.substring(i);
    }
    System.out.println(capital);
    System.out.println(num);
}

Answer 1

我已经尝试过你的代码，下面提到了很多错误以及解决方案

String capital="";
int num=1;
String sentence= "Mi4";
int senLength= sentence.length();
int i=0;
while (i < senLength)//; in the while loop
{
    //String senStr=sentence.substring(i,i+1);  substring should be of 1st letter so (i,i+1) doesnot find letter in next iteration 
    char senChar= senStr.charAt(i);
    if (senChar >= 'A' && senChar <='Z')
    {capital= senStr;}
    else if (senChar >= 'a' && senChar <='z')
    {capital= capital+senStr;}
    else if (senChar >='2' && senChar<='9')
    {num= Integer.parseInt(senStr);}
    i++;
    //sentence=sentence.substring(i);same here in next iteration the string doesnot contains same lenght so it doesnot find char at i
}
System.out.println(capital);
System.out.println(num);