Java - Convert String to Integer

public static int convert(String str){
    char[] chaArray = str.toCharArray();
    int num = 0;
    //365
    //3*10+6 = 36
    //36*10+5 = 365
    for (char c:chaArray) {
        num *= 10;
        num += c-'0';
    }
    return num;
}