Java Double to String conversion without formattin

问题:

I have the number 654987. Its an ID in a database. I want to convert it to a string. The regular Double.ToString(value) makes it into scientific form, 6.54987E5. Something I dont want.

Other formatting functions Ive found checks the current locale and adds appropriate thousand separators and such. Since its an ID, I cant accept any formatting at all.

How to do it?

[Edit] To clarify: Im working on a special database that treats all numeric columns as doubles. Double is the only (numeric) type I can retrieve from the database.

回答1:

Use Long:

long id = 654987;
String str = Long.toString(id);

回答2:

Use a fixed NumberFormat (specifically a DecimalFormat):

double value = getValue();
String str = new DecimalFormat("#").format(value);

alternatively simply cast to int (or long if the range of values it too big):

String str = String.valueOf((long) value);

But then again: why do you have an integer value (i.e. a "whole" number) in a double variable in the first place?

回答3:

If it's an integer id in the database, use an Integer instead. Then it will format as an integer.

回答4:

How about String.valueOf((long)value);

回答5:

What about:

Long.toString(value)

or

new String(value)

回答6:

Also you can use

double value = getValue();

NumberFormat f = NumberFormat.getInstance();
f.setGroupingUsed(false);

String strVal = f.format(value);

回答7:

If what you are storing is an ID (i.e. something used only to identify another entity, whose actual numeric value has no significance) then you shouldn't be using Double to store it. Precision will almost certainly screw you.

If your database doesn't allow integer values then you should stored IDs as strings. If necessary make the string the string representation of the integer you want to use. With appropriate use of leading zeros you can make the alphabetic order of the string the same as the numeric order of the ints.

That should get you round the issue.

回答8:

What about Long.toString((long)value) ?

回答9:

    double d = 56789;
    String s = d+"";