How to nicely format floating numbers to String without unnecessary decimal 0?

Question

A 64-bit double can represent integer +/- 253 exactly

Given this fact, I choose to use a double type as a single type for all my types since my largest integer is unsigned 32-bit.

But now I have to print these pseudo integers, but the problem is they are also mixed in with actual doubles.

So how do I print these doubles nicely in Java?

I have tried String.format("%f", value), which is close, except I get a lot of trailing zeros for small values.

Here's an example output of %f

232.00000000

0.18000000000

1237875192.0

4.5800000000

0.00000000

1.23450000

What I want is:

232

0.18

1237875192

4.58

0

1.2345

Sure I can write a function to trim those zeros, but that's a lot of performance loss due to String manipulation. Can I do better with another format code?

Please note that String.format(format, args...) is locale-dependent 

Answer 1

You can try this to print integers saved as doubles as if they are integers, and unless printing the doubles with the smallest necessary precision:

public static String fmt(double d)

{

    if(d == (long) d)

        return String.format("%d",(long)d);

    else

        return String.format("%s",d);

}

Produces:

232

0.18

1237875192

4.58

0

1.2345

And does not rely on string manipulation.