Java Custom Implementation String type conversion to int

Java custom implements a simple implementation of string conversion to int!

 Public classStringtoint { Public Static intstringtoint (String str) {Char[] num = Str.tochararray ();//get char for each character        intresult = 0;  for(inti = 0; i < num.length; i++){            if(num[i]>57| | NUM[I]&LT;48) {//0~9 corresponding to the Ascall codeSYSTEM.OUT.PRINTLN ("Data format error, conversion failed!!!" "); Throw Newnumberformatexception (); }Else{result+ = (num[i]-48) * (Math.pow, num.length-i-1)); }        }        returnresult; }         Public Static voidMain (string[] args) {String str= "612345"; //String str= "612346a";//Error Format Test        intsum=stringtoint (str);    SYSTEM.OUT.PRINTLN (sum); }    }

Java Custom Implementation String type conversion to int