A method of writing an analytic expression of one's own and obtaining the result (the last is expressed as a double, in which the middle result is computed by the BigDecimal, the temporary whim is written, no comment)

Package calcutor;

Import Java.math.BigDecimal;
Import java.util.ArrayList;
Import Java.util.regex.Matcher;
Import Java.util.regex.Pattern;

public class calcutor{

public static BigDecimal GetResult (arraylist<string> list) {
if (list.size () = = 3) {

if ("+". Equals (List.get (2))) {
return new BigDecimal (List.get (0)). Add (New BigDecimal (List.get (1)));
}else if ("-". Equals (List.get (2)) {
return new BigDecimal (List.get (0)). Subtract (New BigDecimal (List.get (1));

}else if ("*". Equals (List.get (2)) {
return new BigDecimal (List.get (0)). Multiply (New BigDecimal (List.get (1));
}else if ("/". Equals (List.get (2))) {
return new BigDecimal (List.get (0)). Divide (New BigDecimal (List.get (1)), 1000,bigdecimal.round_up);

}else if ("^". Equals (List.get (2)) {
return new BigDecimal (Integer.parseint (list.get (0)) ^integer.parseint (List.get (1)));
}
}

Arraylist<string> List1 = new arraylist<string> ();

for (int i = 0;i<list.size (); i++) {

if (Priorityenum.getenumlist (). Contains (List.get (i))) {
List1.addall (list.sublist (0, i-2));
String s = "";
if ("+". Equals (List.get (i))) {

s = new BigDecimal (List.get (I-2)). Add (New BigDecimal (List.get (i-1)). ToString ();

}else if ("-". Equals (List.get (i)) {
s = new BigDecimal (List.get (i-2)). Subtract (new BigDecimal (List.get)). ToString ();

}else if ("*". Equals (List.get (i)) {
s = new BigDecimal (List.get (i-2)). Multiply (new BigDecimal (List.get)). ToString ();
}else if ("/". Equals (List.get (i))) {
s = new BigDecimal (List.get (i-2)). Divide (new BigDecimal (List.get), i-1). toString ();

}else if ("^". Equals (List.get (i)) {
s = "" + New BigDecimal (Integer.parseint (list.get (0)) ^integer.parseint (List.get (1));

}
List1.add (s);
List1.addall (List.sublist (i+1, List.size ()));
list = null;
Return GetResult (List1);
}
}
return Bigdecimal.zero;
}

public static arraylist<string> Readformula (String formula) {

Arraylist<string> List1 = new arraylist<string> ();
arraylist<string> list2 = new arraylist<string> ();
String s = "";

for (int i = 0; i< formula.length (); i++) {
if (!isc (Formula.charat (i))) {
List1.add (s);
List1.add ("" +formula.charat (i));
s = "";
} else {
S + + Formula.charat (i);
}
}

if (s!= null && s.length ()!= 0) {List1.add (s);}

for (String String:list1) {
if (string!= null && string.length ()!= 0) {list2.add (string);
}
List2.trimtosize ();
return list2;
}

public static Boolean isnumber (String target) {
if (target = null | | target.length () = = 0) {
return false;
}

Pattern pattern =
Pattern.compile ("[0-9]+\\.") [0-9]* ");
Matcher Matcher = Pattern.matcher (target);
return matcher.matches ();
}

public static Boolean IsC (char c) {

String target = "" +C;

if (target = null | | target.length () = = 0) {
return false;
}

Pattern pattern =
Pattern.compile ("[0-9]?\\.?");
Matcher Matcher = Pattern.matcher (target);
return matcher.matches ();
}

public static arraylist<string> sort (arraylist<string> list) {

  ArrayList<String> list1 = new arraylist<string> ();
  ArrayList<String> list2 = new arraylist<string> ();
  list1.add ("#");
  list.add ("#");
  for (String str:list) {
   if (isnumber (str)) {
     List2.add (str);
   } else{
    if (")". Equals (str)) {
      while (List1.size () > 0) {
      if () (. Equals (List1.get (List1.size ()-1)) {
       list1.remove (List1.size ()-1);
       break;
      }
      list2.add (List1.get (List1.size ()-1));
      list1.remove (List1.size ()-1);
     }

} else{
if (PRIORITYENUM.GETICP (str) > Priorityenum.getisp (List1.get (List1.size ()-1)) {
List1.add (str);
}else{

while (List1.size () > 0) {
if (PRIORITYENUM.GETICP (str) < Priorityenum.getisp (List1.get (List1.size ()-1)) {
if (! ")". Equals (List1.get (List1.size ()-1)) &&! " (". Equals (List1.get (List1.size ()-1)) &&!" # ". Equals (List1.get (List1.size ()-1))" {
List2.add (List1.get (List1.size ()-1));
}
List1.remove (List1.size ()-1);
} else {
Break
}
}
if (PRIORITYENUM.GETICP (str) > Priorityenum.getisp (List1.get (List1.size ()-1)) {
List1.add (str);
}
}
}
}

}

List1 = null;
List2.trimtosize ();
return list2;
}

}

Package calcutor;

Import java.util.ArrayList;

public enum Priorityenum {

A ("#", 0, 0)

, Left ("(", 8,1)

, right (")", 1,8)
, Divide ("/", 4,5)
, Multi ("*", 4,5)
, Mul ("%", 4,5)
, head ("^", 6,7)
, Plus ("+", 2, 3)
, Minus ("-", 2, 3);

Private final String param;

private final int ICP;

private final int ISP;

Private Priorityenum (String param, int ICP, int ISP) {
This.param = param;
THIS.ICP = ICP;
This.isp = ISP;
}

@Override
Public String toString () {
return this.param;
}

Public String GetParam () {
return this.param;
}

public static int GETICP (String param) {
For (Priorityenum v:values ()) {
if (V.getparam (). Equals (param)) {
return V.ICP;
}
}
return 0;
}
public static int getisp (String param) {
For (Priorityenum v:values ()) {
if (V.getparam (). Equals (param)) {
return v.isp;
}
}
return 0;
}
public static arraylist<string> Getenumlist () {
arraylist<string> list = new arraylist<string> ();
For (Priorityenum v:values ()) {
List.add (V.getparam ());
}
List.trimtosize ();
return list;
}
}

Package calcutor;

Import java.util.ArrayList;
Import Java.util.Scanner;
public class Run {
public static void Main (string[] args) {

Scanner sc = new Scanner (system.in);
String s = sc.nextline ();
String s = "11+12* (13-14) -15/16* (12+1.5* (3+5.2))";
String s = "12.6 + 13.5*6";
S =s. Replace ("", "");
arraylist<string> list = Calcutor.readformula (s);
Arraylist<string> List1 = calcutor.sort (list);
for (String String:list1) {
System.out.print (string+ "");
}
System.out.println ();
System.out.println (Calcutor.getresult (List1). Doublevalue ());
Double A = 1*13*15* (5+9) * (12.0/9+9* (3+5));
System.out.println (12^14);
System.out.println (a);
}
}