Negative Cell Value Styles in Apache POI

Question

Using Apache POI to generate a document and i'm having a small problem with cell styles, currentlly i'm using:

CellStyle currencyCellStyle=workbook.createCellStyle();
currencyCellStyle.setDataFormat(format.getFormat("$#,##0.00"));

Which works totally fine for positive numbers, however I would like to assign a different style to negative cells automatically.

Question is is there any to set this up without having to check the individual cell values and assign a separate style to them?

Or alternatively is there any way to tell Apache POI to use the built in excel currency format with one of its negative options?

Answer 1

Found it, thanks me :D

CellStyle currencyCellStyle=workbook.createCellStyle();
currencyCellStyle.setDataFormat(format.getFormat("$#,##0.00;[Red]($#,##0.00)"));

Answer 2

Why poi REFUSES to support the FIRST option in excel currency formatting is beyond me!

I don't like using the DecimalFormat for currency because your end cell value becomes a non-numeric with the introduction of the currency symbol. While working for a major financial institution, I was tasked with resolving this formatting issue. The core idea of this change is, because POI refuses to be reasonable and have comprehensive support of Excel's native options, I will infiltrate their code and change their values at the core. The following is my WORKAROUND:

private static final String CURRENCY_FORMAT_OVERRIDE = "\"$\"#,##0.00_);-\"$\"#,##0.00";
private static final String CURRENCY_FORMAT_TARGET = "\"$\"#,##0.00_);(\"$\"#,##0.00)";    

static { // static class level initializer
    Field field = org.apache.poi.ss.usermodel.BuiltinFormats.class.getDeclaredField("_formats");            
    field.setAccessible(true);
    String[] _formats = (String[])field.get(new org.apache.poi.ss.usermodel.BuiltinFormats());
    for(int i = 0; i < _formats.length; ++i) {
        if(_formats[i].equals(CURRENCY_FORMAT_TARGET)) {
            _formats[i]=CURRENCY_FORMAT_OVERRIDE;
            System.out.println("TAKE THAT, POI!!!");
        }
    }
}