CODEWITHSUNDEEP
javadouble
Vikram
Vikram

Reputation: 4106

How to avoid Double values getting stored in 1Ex format?

I am having a double variable:

private double b=0.0;

I am taking value of a certain field in b (the value is between 0.0 to 9.99999999). Mostly, user enters value between 0.0 to 1.0.

When I am saving the value from user in 'b', and if the value is 0.000001, then it is getting saved as 1E-6 and next time displayed as same on the screen (this is because b is Double).

Is there any way (just by calling some method) in Java, that I can avoid the conversion of value to 1E-6 format? I want to save the value as entered by user only (0.000001).

Upvotes: 3

Views: 1518

Answers (2)

dustmachine
dustmachine

Reputation: 10814

It's true that the number isn't stored in memory using the scientific (E) notation.

You can demonstrate this to yourself by formatting the number differently when you output it:

@Test
public void testLittle() {
    double myNum = 0.000001;
    System.out.printf("%f \n",myNum);
}

You should definitely heed other advice posted in answers here and use BigDecimal if you really want the output to match the input, since some floating-point values aren't what you think they are when representing them in a computer. (ref: IEEE-754)

The "Java Puzzlers" presentations sometimes discuss these odd behaviors and are always a fun way to learn. (See this talk from Google I/O 2011, a bit after 3 minutes in)

Upvotes: 2

Jon Skeet
Jon Skeet

Reputation: 1500875

The double isn't actually "saved" as a string at all. That's just a matter of formatting - for which you should see DecimalFormat. However, it definitely won't be exactly 0.000001 because that number isn't exactly representable as a double. I would strongly recommend that you use BigDecimal instead when precise decimal values matter (as it sounds like they do here).

Upvotes: 12

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