Arithmetic code (Java version) with regular expressions

Subtraction negative numbers, brackets, and several
See the Code and Comments  (test did not find the bug, such as found a bug, please correct me)

 Packagecom.test;Importjava.util.ArrayList;Importjava.util.List;ImportJava.util.regex.Matcher;ImportJava.util.regex.Pattern;/*** Arithmetic, may not be the best way of writing, their own test did not find bug<br> * Premise: The correct formula, because did not do the verification of the formula <br> * Ideas:<br> * 1, with regular split all the elements of the example: 2-5+4*5/( 2) -4<br> * split into "2,-5,4,*,5,/, (, 2, 2,), 4" <br> * 2, calculate parentheses first, multiplication, last add minus * * Summary: Total spent 17, 8 hours, the main reason is not careful overall analysis process caused. <br> * So that the idea of the point of writing code, revision changes, not a complete grasp of the idea. So a problem must be <br> * First walk through the whole idea, the process is actually coding is the easiest, the focus is the process of thinking * *@authorWangshiyan * @time 2014-12-4 pm 12:50:01 **/ Public classSizhetool { Public Static voidMain (string[] args) {Try{System.out.println (Jisuanstr ("11.2+3.1* (423-(2+5.7*3.4) +5.6) -6.4/(15.5+24)")); } Catch(Exception e) {System.out.println ("Please check your calculation format");        E.printstacktrace (); }    }    /*** Split the various elements in the calculation and handle the corresponding position <br> * *@paramSTR *@return     */     Public StaticList<string> splitstr (String string)throwsException {List<String> Listsplit =NewArraylist<string>(); Matcher Matcher= Pattern.compile ("\\-?\\d+ (\\.\\d+)? | [*/()]|\\-"). Matcher (string);//split into each element with a regular         while(Matcher.find ()) {//System.out.println (matcher.group (0));Listsplit.add (Matcher.group (0)); }        returnListsplit; }    /*** Calculation <br> * Steps: 1, if there are brackets <br> * then take the previous nearest (coordinate calculation of the current parentheses in the formula), continue to look for parentheses and so on, until the loop uses all the coordinate elements * calculation Complete (Operation order parentheses, multiplication, plus minus) * *@paramSTR *@return     */     Public Static DoubleJISUANSTR (String str)throwsException {Doublereturndouble = 0; List<String> listsplit = splitstr (str);//split the good elementsList<integer> zkuohaoidxlist =NewArraylist<integer> ();//left parenthesis,< coordinates,>        if(Pattern.compile (". *\\ (|\\). *"). Matcher (str). FIND ()) {//If you include the parentheses operationString value = "";//Single character value            intZidx = 0;//Subscript of the last left parenthesis in zkuohaoidxlist//this layer loops through all the calculations in parenthesesList<string> templist =NewArraylist<string> ();//elements that are not previously evaluated            intRemovel = 0; intTemplistsize = 0;  for(inti = 0; I < listsplit.size (); i++) {Value=Listsplit.get (i);                Templist.add (value); Templistsize=templist.size (); if((". Equals (value)") {//opening parenthesisZkuohaoidxlist.add (tempListSize-1); } Else if(")". Equals (value)) {//computes the calculation with the closing parenthesis between the previous opening parenthesisZidx = Zkuohaoidxlist.size ()-1;//match the nearest left parenthesis to the current closing parenthesis                    intStart =Zkuohaoidxlist.get (ZIDX); Returndouble= Jisuan (templist, start + 1, tempListSize-1);//start position, which is the last left parenthesisRemovel = Templistsize-start; Templist= Removeuselist (templist, removel);//remove an already used elementTemplist.add (returndouble + "");//just calculate the value to add inZkuohaoidxlist.remove (ZIDX);//finish calculation Clear parentheses                }            }            //finish all the calculations .returndouble = Jisuan (templist, 0, Templist.size ()); } Else{//no parentheses Operationreturndouble = Jisuan (listsplit, 0, Listsplit.size ()); }        returnreturndouble; }    /*** Reverse deletion of used elements * *@paramlist *@paramremovelength * Quantity *@return     */     Public StaticList<string> removeuselist (list<string> List,intremovelength) {        intLe = List.size ()-removelength;  for(inti = List.size ()-1; I >= le; i--) {list.remove (i); }        returnlist; }    /*** Calculation Formula * *@paramListsplit *@paramStart * Bracket calculation start position *@paramEnd * Bracket Terminator position *@return     */     Public Static DoubleJisuan (list<string> Listsplit,intStartintend)throwsException {Doublereturnvalue = 0; String strvalue=NULL;//Temp VariableList<string> jjvaluelist =NewArraylist<string> ();//the remaining plus and minus elements//Traverse Calculation Multiplication Method         for(inti = start; I < end; i++) {strvalue=Listsplit.get (i); if("*". Equals (strvalue) | | "/". Equals (strvalue)) {//multiplicationstrvalue = Jisuanvalue ("*". Equals (strvalue)? "*" : "/", Double. Parsedouble (Jjvaluelist.get (jjvaluelist.size ()-1)), double.parsedouble (Listsplit.get (i+ 1)))                        + ""; Jjvaluelist.remove (Jjvaluelist.size ()-1); I++;        } jjvaluelist.add (strvalue); }        //traverse calculation plus minus         for(intj = 0; J < Jjvaluelist.size (); J + +) {strvalue=Jjvaluelist.get (j); if("-". Equals (strvalue) | | "+". Equals (strvalue)) {returnvalue= Jisuanvalue ("-". Equals (strvalue)? "-" : "+", ReturnValue, Double.parsedouble (Jjvaluelist.get (J+ 1))); J++; } Else{returnvalue+=double.parsedouble (Jjvaluelist.get (j)); }        }        returnreturnvalue; }    /*** Calculate the subtraction operation of 2 numbers such as: 2*5, 2/5 * *@paramtype * operator *@paramstart * Number equals above 2 *@paramend * is counted equivalent to 5 above *@return     */     Public Static DoubleJisuanvalue (String type,DoubleStartDoubleend)throwsException {Doubled = 0; if("-". Equals (Type) {D= Start-end; } Else if("+". Equals (Type) {D= Start +end; } Else if("*". Equals (Type) {D= Start *end; } Else if("/". Equals (Type) {            if(0 = = Start | | 0 = =end) d= 0; ElseD= Start/end; }        returnD; }}

Arithmetic code (Java version) with regular expressions