Converting String to Integer without using a built in method

Converting String to Integer without using a built in method

public class TestStringtoInt {

public static void main(String []args){

String s="-s234.23";

char[]a=s.toCharArray();

int sum=0;

for(int i=0;i<a.length;i++){

int number=a[i]-'0';

sum=sum*10+number;

System.out.println(sum);

}

}

}