validation - Java - validate operator -

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i written below program, confused on part b of question. question is- write program evaluate simple expressions such 17 + 3 , 3.14159 * 4.7. expressions typed in user. input consists of number, followed operator, followed number. operators allowed +, -, *, , /. not required perform data validation here done in part (b) below. program output must show expression entered result (e.g. 17 + 3 = 20).

part b: modify program in part (a) above validate operator entered. program repeats input until valid operator entered. required make use of method validation.

here's wrote

import java.util.scanner; public class javacalculator {      public static void main(string[] args)    {        scanner console = new scanner(system.in);        double digit1;        double digit2;        double total;        string operator1;          system.out.print("enter 1st number: ");        digit1 = console.nextdouble();         system.out.print("enter operator: ");        operator1=console.next();             system.out.print("enter 2nd number: ");        digit2 = console.nextdouble();          if (operator1.equals("-"))       {         total = digit1-digit2;         system.out.println(+digit1+ "-" +digit2+ "=" +total);       }       else if (operator1.equals("+"))       {         total = digit1+digit2;         system.out.println(+digit1+ "+" +digit2+ "=" +total);       }       else if (operator1.equals("*"))       {         total = digit1*digit2;         system.out.println(+digit1+ "*" +digit2+ "=" +total);       }       else if (operator1.equals("+"))       {         total = digit1/digit2;         system.out.println(+digit1+ "/" +digit2+ "=" +total);       }       }  }

just got started out java, please bear me or ignorance here in question. on line should started on part b validate operator?

here have rewritten code. hope fulfill expectation.

 public static void main(string[] args)  {    scanner console = new scanner(system.in);    double digit1;    double digit2;    double total;    string operator = "";     boolean repeatflag = true;    while(repeatflag)   {      system.out.print("enter valid operator(+, -, /, *): ");      operator = console.next();    if(!(operator.equals("+") ||            operator.equals("-") || operator.equals("/") || operator.equals("*")))       {     repeatflag=true;     continue;      }         repeatflag = false;    }     system.out.print("enter 1st number: ");    digit1 = console.nextdouble();    system.out.print("enter 2nd number: ");    digit2 = console.nextdouble();    if (operator.equals("-"))   {     total = digit1-digit2;     system.out.println(+digit1+ "-" +digit2+ "=" +total);   }   else if (operator.equals("+"))   {     total = digit1+digit2;     system.out.println(+digit1+ "+" +digit2+ "=" +total);   }   else if (operator.equals("*"))   {     total = digit1*digit2;     system.out.println(+digit1+ "*" +digit2+ "=" +total);   }   else if (operator.equals("/"))   {     total = digit1/digit2;     system.out.println(+digit1+ "/" +digit2+ "=" +total);   }   }

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