String str = “13abf”;

int len = str.length;

int sum = 0;

for(inti=0;i<len;i++){

char c =str.charAt(len-1-i);

int n =Character.digit(c,16);

sum += n *(1<<(4*i));

}

String str = “13abf”;

int len = str.length;

int sum = 0;

for(inti=0;i<len;i++){

char c =str.charAt(len-1-i);

int n =Character.digit(c,16);

sum += n *(1<<(4*i));

}