编写一个函数将一个十六进制数的字符串参数转换成整数返回

public class TenConvertToHex {

public static void main(String[] args){
TenConvertToHex c = new TenConvertToHex();
String str16Hex = "000F";

long sum = c.str16HexToDigit(str16Hex);
System.out.println(str16Hex+"->(16进制):"+sum);

//使用Integer类实现
long sum2 = Integer.parseInt(str16Hex, 16);
System.out.println(str16Hex+"->(16进制):"+sum2);
}

public long str16HexToDigit(String str16Hex){
int len = str16Hex.length();
long sum = 0;
for(int i=0;i<len;i++){
char c = (char)str16Hex.charAt(len-1-i);
int n = Character.digit(c, 16);
//System.out.println(1<<(4*i));
sum += n*(1<<(4*i));
}
return sum;
}
}