Using return

[Steve Lang]

Can you use return and format the output? Currently i have this:

 	public static double getBillAmount(double bill)
	{
		if(bill > 2000)
		{
			double discounted = bill * 0.85;
			return discounted;
		}
			double notDiscounted = bill;
			return notDiscounted;
	}

Using return i am supposed to format it to only print two decimal places. Also, nothing is currently printing anyway.

[Henry Wong]

You are returning a double. A double is just a floating point value. It doesn't contain any formatting.

If you want the output formatted, either format it to a string using the DecimalFormat class, or format it as it is being printed using the printf() method.

Henry

[Amit Ghorpade]

Also I dont see a reason for the following code

 double notDiscounted = bill;  
  return notDiscounted;  

you can directly return bill without the use of an additional double value. Also in the first case you can directly return bill *0.5. Lastly you can use the ternary operator ?: so your function is reduced to a single line of code.

[Kieren Dixon]

public static double getBillAmount(double bill)
{
	return bill > 2000 ? bill * 0.85 : bill;
} 

[Brian Pianczk]

Henry Wong wrote:You are returning a double. A double is just a floating point value. It doesn't contain any formatting.

If you want the output formatted, either format it to a string using the DecimalFormat class, or format it as it is being printed using the printf() method.

Henry

Henry, are both your suggestions done at print? Since I am new, I have been messing around with this for practice. The best I could do was call the method in main and manipulate the return there.

Is there a specific way to have the method be called with the return already formatted?

This is what I did at print, also did pretty much the same with printf("$%8.2f", getBillAmount(2100.00));

import java.text.*;
 public class BillTest {
 
  public static double getBillAmount(double bill) { 
		
        return bill > 2000 ? bill * 0.85 : bill; 
     }  
	
  public static void main (String [] args) {
		DecimalFormat frmt = new DecimalFormat("0000.00");
		System.out.println("$" + frmt.format(getBillAmount (2100.00)));
	}
}    

[fred rosenberger]

I believe what Henry was saying was that you could either:

a) format the double when you go to print it

or

b) change the method to return a string, and format the double to a string inside the method

[Ernest Friedman-Hill]

Brian Pianczk wrote:
Is there a specific way to have the method be called with the return already formatted?

Again, a double is just a conceptual number; it does not include any kind of formatting. You can write the number 1/3 as 0.33333333333 or 0.3333 or 3.33x10-1, or many other different ways, but they're all represented by the same double value. Formatting happens only when you print a value.

If you want your method to return a specific formatted display of a number, and you'll never actually do any math on the returned value again, then you could have the method return a String, and put the format call into the method -- i.e.,

 public static String getBillAmount(double bill) { 	
        double amount = bill > 2000 ? bill * 0.85 : bill; 
        DecimalFormat frmt = new DecimalFormat("0000.00");
        return frmt.format(amount);
}

... but I wouldn't recommend this. Your original getBillAmount() did one thing: it computed a value. Your new one does two things: computes a value and formats it. In general, you want most of your methods to do just one thing -- that makes the code easier to read, and it's more flexible. If you had a lot of calculation methods and they all formatted their output, and now you decide you need to use a different format, you have to make changes all over the code! If, on the other hand, you did all your formatting and output in one place -- i.e., here, in main() -- then it'd be easy to make the change. So I actually think your original was just fine -- returning the double is a better plan.

Finally, about the advice you got to use the ternary operator: your original method was longer, yes, but it was also nicely self-documenting. The variables "discounted" and "notDiscounted" make the purpose of the code easy to understand. That "ternary operator" has its place, but it's something that should be used sparingly. Here, you've used it to turn a nice, clear, readable method into a terse, unreadable Perl-like blurt. Avoid clever, terse code -- and take all the style advice you get with a grain of salt. Always keep in mind that you, and others, might have to read the code again in a year. Which version would you rather find?

[Brian Pianczk]

Edit: Question was answered as I was writing it, thanks Ernest!