編寫一個函數將一個十六進制數的字符串參數轉換成整數返回

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進制):"+sum);
		
		//使用Integer類實現
		long sum2 = Integer.parseInt(str16Hex, 16);
		System.out.println(str16Hex+"->(16進制):"+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;
	}
}