Thread: String formatting

I'm not very knowledgeable of String formatting, so I was hoping someone could answer what I hope will be an easy question:

I am using String.format to format Strings into some specified pattern. How would I write the format String for currency?

For example, I'd like to convert:
1005.1000032
Into:
$1,005.10

I attempted something as simple as:

"$%.2s"

If I input: 105.1000032
It converts it to: $10

And if I input 1005.1000032
The test program never actually starts up. I assume some sort of infinite loop or something going on, but I don't care right now since my format is incorrect anyway.

What should my format String be? Keep in mind that I am NOT converting it to a number type before formatting it.

Originally Posted by aussiemcgr

Keep in mind that I am NOT converting it to a number type before formatting it.

Why not?

See the Formattable class for ideas on how to have custom formatting of an object's contents.

--- Update ---

BTW Formattable is an interface not class

I was not wanting to convert it to a number first because I am creating a generalized formatting class for a custom swing table class I've made, so I didn't want to restrict the formatting to only numbers. At the moment, I don't know if I'll need to do any formatting with non-numbers, but I'd rather not create an infrastructure which will require me to do a lot of refactoring if that condition does present itself.
Basically, I just have this simple class (with what will be a handful of public constants as "common" formats):

public class TableColumnFormatter {
 
	public static final String MONEY_FORMAT = "$%(,.2s"; 
 
	private String format;
 
	public TableColumnFormatter(String form) {
		format = form;
	}
 
	public String formatCell(String content) {
		return String.format(format,content);
	}
}

I map that class to a column in my custom swing table and it will automatically format the cells in that column when I add objects to the table. The custom swing table has a hell of a lot more extra stuff with it, but this is just one of the things I'm wanting to include.

Although the more I look at examples online, the more it seems like the only way to do this in any simple fashion is with a number...

Are going to use only what the String class's format() method supports?
Or are you trying to extend the formatting rules with your own definitions?
If you are not going to extend what format() supports, what is the purpose of the new class?

There is the very likely possibly down the line that I will attempt to include cell rendering information within the formatting class. However, I haven't really scoped that out yet. For example, the TableColumnFormatter class would contain information for both content formatting and/or rendering flags for a specific column. The TableColumnFormatter then gets mapped to a column so I can resolve formatting and rendering information without having to map both individually. I haven't designed any solid plans for it yet, but I imagine I would set it up so the rendering flags would resolved at table initialization, while the cell formatting is resolved each time an object is added to the table.
Keep in mind that this extremely in the frameworking and designing stage. I have a handful of design plans which I am attempting to implement in a basic fashion to see how realistic my plans are. And then I have other plans which are in an "implement when I need to" state.