Unable to add rows in a PDF table

I tried adding rows under the column. It must display 2 rows which consists of 4 columns each.

The below code provides 1 row and 4 column respectively.

I tried adding cell1.setRowSpan(1) under each cell but that doesn't seems to work.

public class report {
    public static void main(String[] args) {
        Document document = new Document();
        try {
            PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("C:\\Users\\report.pdf"));
            document.open();

            PdfPTable table = new PdfPTable(4); // 4 columns.
            table.setWidthPercentage(100); //Width 100%
            table.setSpacingBefore(10f); //Space before table
            table.setSpacingAfter(10f); //Space after table

            //Set Column widths
            float[] columnWidths = {1f, 1f, 1f , 1f};
            table.setWidths(columnWidths);

            PdfPCell cell1 = new PdfPCell(new Paragraph("Cell 1"));
            cell1.setBorderColor(BaseColor.RED);
            cell1.setBackgroundColor(BaseColor.GRAY);
            cell1.setPaddingLeft(10);
            cell1.setHorizontalAlignment(Element.ALIGN_CENTER);
            cell1.setVerticalAlignment(Element.ALIGN_MIDDLE);

            PdfPCell cell2 = new PdfPCell(new Paragraph("Cell 2"));
            cell2.setBorderColor(BaseColor.RED);
            cell2.setBackgroundColor(BaseColor.GRAY);
            cell2.setPaddingLeft(10);
            cell2.setHorizontalAlignment(Element.ALIGN_CENTER);
            cell2.setVerticalAlignment(Element.ALIGN_MIDDLE);

            PdfPCell cell3 = new PdfPCell(new Paragraph("Cell 3"));
            cell3.setBorderColor(BaseColor.RED);
            cell3.setBackgroundColor(BaseColor.GRAY);
            cell3.setPaddingLeft(10);
            cell3.setHorizontalAlignment(Element.ALIGN_CENTER);
            cell3.setVerticalAlignment(Element.ALIGN_MIDDLE);

            PdfPCell cell4 = new PdfPCell(new Paragraph("Cell 4"));
            cell4.setBorderColor(BaseColor.WHITE);
            cell4.setBackgroundColor(BaseColor.GRAY);
            cell4.setPaddingLeft(10);
            cell4.setHorizontalAlignment(Element.ALIGN_CENTER);
            cell4.setVerticalAlignment(Element.ALIGN_MIDDLE);

            table.addCell(cell1);
            table.addCell(cell2);
            table.addCell(cell3);
            table.addCell(cell4);

            document.add(table);
            document.close();
            writer.close();
        } catch (Exception e) {`enter code here`
            e.printStackTrace();
        }
    }
}

You have already defined your table to have 4 columns:

PdfPTable table = new PdfPTable(4); // 4 columns.

And you have already added 4 cells:

table.addCell(cell1);
table.addCell(cell2);
table.addCell(cell3);
table.addCell(cell4);

So, just keep adding more cells. The 5th cell you add will automatically become the first cell of row 2.

You can repeat your four addCell() statements if you want to see what I mean:

This just repeats the entire first row.