我有一个关于在 Java 中从十进制转换为十六进制的问题。我已经完成了从十进制转换为二进制和八进制的部分代码，但是我在十六进制方面遇到了一些问题，因为我不知道如何使结果显示为 A、B、C、D、E和 F. 这是我的代码：
package transformare1;
import java.io.*;
public class Transformare1 {
public static void main(String[] args)throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println ("Introduceti un numar natural in baza 10 ");
int n = Integer.parseInt(br.readLine());
System.out.println ("Alegeti in ce baza sa fie convertit numarul: 2, 8, 16 ");
int n1 = Integer.parseInt(br.readLine());
if (n1==2){
String b = "";
while (n!=0){
int r = (int)(n%2);
b = r+b;
n /=2;
}
System.out.println ("Numarul binar este "+b);
}
else if (n1==8){
String b = "";
while (n!=0){
int r = (int)(n%8);
b = r+b;
n /=8;
}
System.out.println ("Numarul octal este "+b);
}
else if (n1==16){
String b ="";
while (n!=0){
int r = (int)(n%16);
b = r+b;
n /=16;
final char A=10;
final char B=11;
final char C=12;
final char D=13;
final char E=14;
final char F=15;
}
System.out.println ("Numarul hexadecimal este "+b);
}}
}