Truncate double or add extra 0 to the decimal - Java

Question

This might be a duplicate, but I cannot find any answers that work with my code.

I'm trying to truncate my results for a method(for calculating a fee) in Java. I then try to write the results to a text file, but it's not showing like it should. This is what I get and what I'd like it to return:

Result of fee is 8.4, it should return 8.40
Result of fee is 8.0, it should return 8.00

And so on... Any suggestions please?

This is my entire code for the method:

public Double calculateFee(Parcel pcl) {    
    // Get type of parcel (E, S or X)
    String typeOfParcel = pcl.getParcelID().substring(0,1);
    // Formula for calculating fee
    Double fee = (double) 1 + Math.floor(pcl.getVolume()/28000) + (pcl.getDays()-1);

    // apply a discount to parcels of type "S"
    if (typeOfParcel.equalsIgnoreCase("S")) {
        fee = fee * 0.9;
    }

    // apply a discount to parcels of type "X"
    else if (typeOfParcel.equalsIgnoreCase("X")) {
        fee = fee * 0.8; 
    } 

    // This is what I tried:
    // Tried also using #.##, but no result
    DecimalFormat decim = new DecimalFormat("0.00");
    fee = Double.parseDouble(decim.format(fee));

    return fee;     
}

Why are you parsing the formatted double again to return a double? Just return the string form returned by `DecimalFormat.parse`. — Rohit Jain, Feb 14 '13 at 22:01
Why are you returning a `double` as the result of formatting code, and not a `String`? — Louis Wasserman, Feb 14 '13 at 22:06
I wasn't aware that formatting cannot be applied to type Double. Sorry guys, beginner's mistake. — B.B10, Feb 14 '13 at 22:18

Andy Thomas · Answer 1 · 2013-02-14T22:08:39.870

2

One way is to use String.format().

  Double fee = 8.0;
  String formattedDouble = String.format("%.2f", fee );

Note that a Double doesn't hold a formatted representation of its value.

Additional details about format strings are available here.

edited Feb 14 '13 at 22:08

answered Feb 14 '13 at 22:02

Andy Thomas

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score 1 · Accepted Answer · answered Feb 14 '13 at 22:09

1

The problem here isn't that you are formatting it wrong. You are formatting your double using:

decim.format(fee);

Then, you parse this string, back into a Double, therefore losing your formatting:

Double.parseDouble(...

Just return a String rather than a Double, and don't use Double.parseDouble.

answered Feb 14 '13 at 22:09

aglassman

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Hmm.. Now I understand what I am doing wrong. It makes sense! Thanks @aglassman for you explanation. – B.B10 Feb 14 '13 at 22:15
You should say what to use instead of .parseDouble – Wrong Nov 06 '18 at 11:05
@Wrong The last line of my answer explains what to do. – aglassman Nov 06 '18 at 23:28

Truncate double or add extra 0 to the decimal - Java

2 Answers2