JDK Source Learning reading the analysis of parseint method in-integer class

Method Prototypes:

public static int parseint (String s,int radix);

Input: s represents the string to be converted; Radix represents the integer that needs to be converted into a binary number;

Output: Returns a 32-bit integer.

Algorithm Flowchart:

Code implementations in the JDK:

1         /**2 * String converted to integer3  * @params to convert the string4  * @paramRadix in the system5  * @return6  */7  Public Static intparseint (String S,intRadix) {8     //Boundary Value Processing9     if(s==NULL)Ten         Throw NewNumberFormatException ("null"); One     if(radix<Character.min_radix) { A         Throw NewNumberFormatException ("Radix" +radix+ "less than Character.min_radix"); -     } -     if(radix>Character.max_radix) { the         Throw NewNumberFormatException ("Radix" +radix+ "greater than Character.max_radix"); -     } -      -     intResult=0; +      -     //symbol bit judgment +     BooleanNegative=false; A      at     //string offset pointer -     intI=0; -      -     intDigit; -      -     intmax=s.length (); in      -     //Maximum boundary value to     intlimit; +      -     //maximum boundary value shift right one the     intmultmin; *      $     if(max>0){Panax Notoginseng         //Working with symbols -         if(S.charat (0) = = '-'){ theNegative=true; +             //boundary value is 0x80000000 Alimit=Integer.min_value; thei++; +         } -         Else{ $             //boundary value is -0x7fffffff $limit=-Integer.max_value; -         } -          themultmin=limit/Radix; -         if(i<max) {WuyiDigit=character.digit (S.charat (i++), radix); the             if(digit<0){ -                 Thrownumberformatexception.forinputstring (s); Wu             } -             Else{ Aboutresult=-Digit; $             } -         } -          while(i<max) { -             //converts a character to a corresponding binary integer ADigit=character.digit (S.charat (i++), radix); +             if(digit<0){ the                 Thrownumberformatexception.forinputstring (s); -             } $              the             if(result<multmin) { the                 Thrownumberformatexception.forinputstring (s); the             } theresult*=Radix; -             //Result-digit<limit in             if(result<limit+Digit) { the                 Thrownumberformatexception.forinputstring (s); the             } Aboutresult-=Digit; the         } the     } the     Else{ +         Thrownumberformatexception.forinputstring (s); -     } the     if(negative) {Bayi         if(i>1){ the             returnresult; the         } -         Else{ -             Thrownumberformatexception.forinputstring (s); the         } the     } the     Else{ the         return-result; -     } the}

Key points:

1. The boundary value of positive number is 1 to 0x7fffffff; the boundary value of negative number is 1 to 0x80000000;
2. The code handles all data as negative numbers (positive numbers) and finally handles symbolic problems;
3. This variable is multmin in the method in order to Result*=radix in the loop without crossing the bounds;

JDK Source Learning Read the analysis of parseint method in-integer class (GO)