Setting filter on headers of an Excel sheet via POI

easiest way of adding filter on header :

sheet.setAutoFilter(new CellRangeAddress(0, 0, 0, numColumns));
sheet.createFreezePane(0, 1);

Save the first and last cell from filter area, and execute:

sheet.setAutoFilter(new CellRangeAddress(firstCell.getRow(), lastCell.getRow(), firstCell.getCol(), lastCell.getCol()));

For example, from the below sheet.

>x         (x, y)
  0123456  
0|--hhh--|   h = header
1|--+++--|   + = values
2|--+++--|   - = empty fields
3|--+++--|
4|-------|

first cell will be the header above the first + (2,1) cell. The last will be the last + cell (5,3)

If you also want to set a filter programmatically, you could use the following:

void setAutoFilter(final XSSFSheet sheet, final int column, final String value) {
    sheet.setAutoFilter(CellRangeAddress.valueOf("A1:Z1"));

    final CTAutoFilter sheetFilter = sheet.getCTWorksheet().getAutoFilter();
    final CTFilterColumn filterColumn = sheetFilter.addNewFilterColumn();
    filterColumn.setColId(column);
    final CTFilter filter = filterColumn.addNewFilters().insertNewFilter(0);
    filter.setVal(value);

    // We have to apply the filter ourselves by hiding the rows: 
    for (final Row row : sheet) {
        for (final Cell c : row) {
            if (c.getColumnIndex() == column && !c.getStringCellValue().equals(value)) {
                final XSSFRow r1 = (XSSFRow) c.getRow();
                if (r1.getRowNum() != 0) { // skip header
                    r1.getCTRow().setHidden(true);
                }
            }
        }
    }
}

Relevant Gradle dependencies:

    // https://mvnrepository.com/artifact/org.apache.poi/poi
compile group: 'org.apache.poi', name: 'poi', version: '3.9'

// https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml
compile group: 'org.apache.poi', name: 'poi-ooxml', version: '3.9'

// https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml-schemas
compile group: 'org.apache.poi', name: 'poi-ooxml-schemas', version: '3.9'

// https://mvnrepository.com/artifact/org.apache.poi/ooxml-schemas
compile group: 'org.apache.poi', name: 'ooxml-schemas', version: '1.3'