package breaking_it_down;
import java.util.Scanner;
public class TooMuchInMain { public static void main(String[] args) { Scanner scan = new Scanner(System.in); int operand1, operand2, answer; char operator='q'; boolean keepCalculating = true;
while (keepCalculating) { //************************************************* // This next block will get the user desired operator // getOperator should contain the following logic //************************************************* boolean operator_is_good=false;
do {
System.out.print("Enter an Operator: +  - *  /  q for
quit: ");
String strOperator = scan.nextLine(); strOperator = strOperator.trim(); if (strOperator.length() == 0) continue; // Need to try this again with no input operator = strOperator.charAt(0); operator_is_good=false;
switch (operator) { case 'q': case '+': case '-': case '*': case '/': operator_is_good = true; break; default: System.out.println("Your operator is bad ... try
again:");
break;
} } while (!operator_is_good);
//*********************************************** // At this point operator contains a proper operator chosen
by the user
// This will show up in doCalculation //*********************************************** if (operator == 'q') { keepCalculating=false; // not really needed because we are doing a break... but clarifies what will happen break; }
//*********************************************** // Now get operand 1 // getOperand() will get the next hunk of logic //*********************************************** int which =1; System.out.println("Enter operand "+which); String input;
boolean operand_is_bad;
do {
operand_is_bad=false;
input = scan.nextLine(); input = input.trim(); if (input.length() == 0) operand_is_bad=true; for (int i=0; i < input.length(); i++) { char c = input.charAt(i); if (c < '0' || c > '9') { // Oops, bad digit operand_is_bad=true; System.out.println("Your last input was bad, try
again");
}
} } while (operand_is_bad);
// The following statement will be covered later in the
course.
// For now, just know that it converts a String to an integer // Note that Integer.parseInt is picky and blows up with any
bad characters
operand1 =  Integer.parseInt(input);
//*********************************************** // Now get operand 2 // Note this code is mostly the same as the above code.  // You can just reuse the same getOperand method again //*********************************************** which =2;
System.out.println("Enter operand "+which); do { operand_is_bad=false;
input = scan.nextLine(); input = input.trim(); if (input.length() == 0) operand_is_bad=true; for (int i=0; i < input.length(); i++) { char c = input.charAt(i); if (c < '0' || c > '9') { // Oops, bad digit operand_is_bad=true; System.out.println("Your last input was bad,
try again");
}
} } while (operand_is_bad);
// The following statement will be covered later in the
course.
// For now, just know that it converts a String to an integer // Note that Integer.parseInt is picky and blows up with any
bad characters
operand2 =  Integer.parseInt(input);
//*********************************************** // Now we have operator, operand1, and operand2. // Time to calculate the answer // doArithmetic will take the following logic //*********************************************** switch(operator) { case '+': answer = operand1 + operand2; break; case '-': answer = operand1 - operand2; break; case '*': answer = operand1 * operand2; break; case '/': answer = operand1 / operand2; break; default: System.out.println("We shouldn't get here in doArithmentic!!!!"); answer = -1; break; }
//***********************************************
// Time to format the answer // the format routine will get the following statement //*********************************************** System.out.println(operand1 + " "+ operator + " "+ operand2 + " = "+ answer);
System.out.println("======================="); } // end of while (continue_calculating)
System.out.println("Finished Calculations");
} // end of main
} // end of class TooMuchInMain