string to int

StringToInt.java

//From OJ handbook
public class StringToint{
 
  public int atio(String str){
    int i = 0;
    int n = str.length();
 
    while(i < n && Character.isWhiteSpace(str.charAt(i))) i++;
    
    int sign = 1;
 
    if(i < n &&  str.charAt(i) == "+") i++;
    else if(i < n && str.charAt(i) == "-") {
      i++;
      sign = -1;
    }
 
    int num = 0;
 
    while(i < n && Character.isDigit(str.charAt(i))){
      int digit = Character.getNumericValue(str.charAt(i));
      
      if(num > maxDiv10 || num == maxDiv10 && digit >= 8){ //this takes care of the MIN_VAL edge case
        return sign == 1 ? Integer.MAX_VALUE : Integer.MIN_VALUE;
      }
      
      num = num * 10 + digit;
      i++;
    }
    
    return sign * num;
  }
 
 private static final maxDiv10 = Integer.MAX_VALUE / 10;
 

  
}