The tutor continues about number formatting with Java.

We don’t live in countries any more; rather,  we live in the world.  Right now, for instance, my family is off in the US.  I’m not with them; I stayed home to run the business.  In fact, I’m not a traveller.

I learn about the world from print, which is how  I recently became aware that number formats vary from country to country.  Behold the many faces of 1 139 275.78:

Notice that none of those nation-specific formats is the way I write the number (once again: 1 139 275.78). I was taught that, in Metric, the thousands separators are spaces, not commas. Yet, being in an English-speaking country, I use a decimal point rather than a comma. It’s an interesting mash of formats that I believe scientifically-educated North Americans commonly use:)

Being an international programming language, Java is prepared to accommodate the number formats used in different countries. Java calls a country a locale.

I wrote two earlier posts on Java decimal number formatting here and here. Any Java programmer who is reading this article likely wants the key lines that enable a program to translate a number from one country’s format to another’s. You start with an instance of NumberFormat, setting it with the desired locale:

NumberFormat numform = NumberFormat.getInstance(Locale.COUNTRY)

For example, to get the format used in France:

NumberFormat numform0 = NumberFormat.getInstance(Locale.FRANCE);

Next, you cast the NumberFormat instance into a DecimalFormat object:

DecimalFormat decform0 = (DecimalFormat)numform0;

Finally, you apply the format descriptor string; for example,

decform0.applyPattern(“#,##0.00”);

Now, you can format number num0 to String string0, in the style of France:

string0 = decform0.format(num0);

To use the above code effectively, you’ll need to include the lines

import java.text.NumberFormat;
import java.text.DecimalFormat;
import java.util.Locale;

above the class definition.

As far as I’ve read, not necessarily every country has a locale in Java. You can see which ones do here.

HTH:)

Other sources:

docs.oracle.com

stackoverflow.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.