我想弄清楚如何將十六進制轉換為字符串和整數，以便我可以通過它的串行端口操作我的 arduino 微控制器上的 RGB 燈。我在 java 網站上找到了一個很好的例子，但是我很難理解其中的一些方法，而且我被掛斷了。我可以輕松地復制粘貼此代碼并使其工作，但我想完全理解它。我將在我的理解中添加評論，希望有人可以提供一些反饋。public class HexToDecimalExample3{    public static int getDecimal(String hex){    //this is the function which we will call later and they are declaring string hex here. Can we declare string hex inside the scope..?    String digits = "0123456789ABCDEF";      //declaring string "digits" with all possible inputs in linear order for later indexing             hex = hex.toUpperCase();        //converting string to uppercase, just "in case"             int val = 0;                    //declaring int val. I don't get this part.             for (int i = 0; i < hex.length(); i++)  //hex.length is how long the string is I think, so we don't finish the loop until all letters in string is done. pls validate this             {                   char c = hex.charAt(i);     //char is completely new to me. Are we taking the characters from the string 'hex' and making an indexed array of a sort? It seems similar to indexOf but non-linear? help me understand this..                 int d = digits.indexOf(c);  //indexing linearly where 0=1 and A=11 and storing to an integer variable                 val = 16*val + d;           //How do we multiply 16(bits) by val=0 to get a converted value? I do not get this..             }               return val;  }  public static void main(String args[]){    System.out.println("Decimal of a is: "+getDecimal("a"));  //printing the conversions out.System.out.println("Decimal of f is: "+getDecimal("f"));  System.out.println("Decimal of 121 is: "+getDecimal("121"));  }}    總結一下評論，主要是 char c = hex.charAt(i); AND val = 16*val + d; 我不明白的部分。