Java programs, writing calculators through scanner

 Packagetest;ImportJava.util.Scanner;ImportJava.util.regex.Matcher;ImportJava.util.regex.Pattern;classCalculator {PrivateDouble NUM1; PrivateDouble num2; PrivateString var; PrivateScanner input;  PublicDouble getNum1 () {returnNUM1; }     Public voidsetNum1 (Double num1) { This. NUM1 =NUM1; }     PublicDouble getNum2 () {returnnum2; }     Public voidsetNum2 (Double num2) { This. num2 =num2; }     PublicString GetVar () {returnvar; }     Public voidSetVar (String var) { This. var =var; }     PublicScanner GetInput () {returninput; }     Public voidsetinput (Scanner input) { This. Input =input; }     Public Booleaninput1 () {System.out.println ("Please enter first number"); String Num1str=Input.next (); if(! This. Isnumber (NUM1STR))            {input1 (); }Else{                 This. NUM1 =double.valueof (NUM1STR); }            return true; }     Public BooleanInput2 () {System.out.println ("Enter a second number:"); String Num2str=Input.next (); if(! This. Isnumber (NUM2STR))        {Input2 (); }Else if(Var.equalsignorecase ("/") &&num2str.equalsignorecase ("0")) {System.err.println ("Divisor cannot be 0");        Input2 (); }Else{             This. num2 =double.valueof (NUM2STR); }        return true; }     Public BooleanInputvar () {System.out.println ("Input calculation symbol: +-*/"); String Varstr=Input.next (); Pattern Pat=pattern.compile ("[+-\\\\*/]"); Matcher Match=Pat.matcher (VARSTR); Booleanflag=match.matches (); if(flag==false) {System.err.println ("The operation symbol is incorrect!" ");         Inputvar (); }Else{              This. SetVar (VARSTR); }                 return true; }         Public voidgocal () {Scanner input=NewScanner (system.in);  This. SetInput (input); Booleanflag1= This. INPUT1 (); if(FLAG1) {if( This. Inputvar ()) {                if( This. Input2 ())                {Calculate (); }            }        }    }     Public voidcalculate () {Try {            Switch(Var) { Case"+": System.out.println (NUM1+ "+" +num2+ "=" + (num1+num2));  Break;  Case"-": System.out.println (NUM1+ "-" +num2+ "=" + (num1-num2));  Break;  Case"*": System.out.println (NUM1+ "-" +num2+ "=" + (num1*num2));  Break;  Case"/": System.out.println (NUM1+ "/" +num2+ "=" + (num1/(Double) (num2)) ;  Break; default:                 Break; }        } Catch(Exception e) {//TODO auto-generated Catch blockE.printstacktrace (); if(input!=NULL) {input.close (); System.exit (0); }        }        if(input!=NULL) {input.close (); System.exit (0); }           }     Public Booleanisnumber (Object obj) {if(obj==NULL|| Obj.tostring (). Equals ("")){            return false; } Pattern Pattern=pattern.compile ("[0-9]+.*[0-9]*"); String Str=obj.tostring (); Matcher Matcher=Pattern.matcher (str); Booleanflag=matcher.matches (); if(flag==false) {System.err.println ("Please enter a valid value!" "); }        returnFlag; }} Public classTESTB { Public Static voidMain (string[] args) {Calculator cal=NewCalculator ();                    Cal.gocal (); }}

Java programs, writing calculators through scanner