字符串整数互转

整数转为字符串

public static String intToString(int n){
        String str="";
        boolean isPostive = n>0?true:false;
        n = Math.abs(n);
        while(n>0){
            int m=n%10;
            str=m+str;
            n=n/10;
        }
        
        return isPostive == true ? str : "-"+str;
        
        
    }

字符串转整数：

public int myAtoi(String str) {
        if(str == null || str.length() ==0 ) return 0;
         str = str.trim();
         boolean isPositive = true;
         boolean isOverFlow = false;
         long res = 0;
         for(int i = 0 ; i < str.length(); i++)
         {
             char ch = str.charAt(i);
             if(i ==0 && (ch == '-' || ch == '+'))
             {
                 if(ch == '-')
                 {
                     isPositive = false;
                 }
                 continue;
             }
             if(ch > '9' || ch < '0')  break;//"+-2"  " -0012a42"
             res = res * 10 + (ch - '0');   
             if( res >  Integer.MAX_VALUE)
                 isOverFlow = true;
         }
         res = isPositive == true ? res : -res;
         
         if( isOverFlow == true &&  isPositive == true )
             return  Integer.MAX_VALUE;
         else if(isOverFlow == true &&  isPositive == false )
             return  Integer.MIN_VALUE;
         else
        return (int) res;
  }