Apache POI - How to set correct column width in Word table - apache-poi

Question

I have an existing Word document containing a table. The first row of the table has two cells, but all the other rows have four cells and each cell has a different width.
I need to insert new rows via POI that also have four cells with widths that match those of the existing 4-cell rows.
The basic code is:
XWPFTable table = doc.getTableArray(0);
XWPFTableRow oldRow = table.getRow(2);
table.insertNewTableRow(3);
XWPFTableRow newRow = table.getRow(3);
XWPFTableCell cell;
for (int i = 0; i < oldRow.getTableCells().size(); i++) {
cell = newRow.createCell();
CTTblWidth cellWidth = cell.getCTTc().addNewTcPr().addNewTcW();
BigInteger width = oldRow.getCell(i).getCTTc().getTcPr().getTcW().getW();
cellWidth.setW(width); // sets width
XWPFRun run = cell.getParagraphs().get(0).createRun();
run.setText("NewRow C" + i);
}
The result of this is that row 3 has four cells but their widths do not match those of row 2. The total new row width ends up being the same as the total width of the first three cells of row 2. (Sorry, I don't know how to paste the Word table here).
However, if I first manually edit the source document so that the first table row also has four cells, then everything works perfectly. Similarly, if I get a reference to an existing row and add it to the table, then the cell widths are also correct (but I have the same row object twice so can't modify it).
It seems that the number of cells in the first row influences how other rows are inserted. Does this make sense to anyone and can you suggest how to override it? Also, is there a document anywhere that I can study to understand how this works? Thanks.

Answer 1

Accordiing to your mention: "The first row of the table has two cells, but all the other rows have four cells and each cell has a different width." I suspect this will be a very messy table. Although Word is supporting such tables, I would try to avoid such. But if it must be, you need to know that there is a table grid also for those messy tables. Unzip the *.docx and have a look at /word/document.xml there you will find it.
So if we want to insert rows into such messy tables, we also must respect the table grid. For this there is a GridSpan element in the CTTcPr. This we must also copy from the oldRow and not only copy the CTTblWidth.
Also the CTTblWidth has not only a width but also a type. This we also should copy.
Example:
The source.docx looks like this:
As you see the table grid has 10 columns in total. "Cell 2 1" spans 3 columns, "Cell 2 2" spans 3 columns, "Cell 2 3" spans 0 columns (is its own column), "Cell 2 4" spans 3 columns.
With code:
import java.io.*;
import org.apache.poi.xwpf.usermodel.*;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.openxmlformats.schemas.wordprocessingml.x2006.main.CTTblWidth;
import org.openxmlformats.schemas.wordprocessingml.x2006.main.CTTcPr;
import java.math.BigInteger;
public class WordInsertTableRow {
public static void main(String[] args) throws IOException, InvalidFormatException {
XWPFDocument doc = new XWPFDocument(new FileInputStream("source.docx"));
XWPFTable table = doc.getTableArray(0);
XWPFTableRow oldRow = table.getRow(2);
table.insertNewTableRow(3);
XWPFTableRow newRow = table.getRow(3);
XWPFTableCell cell;
for (int i = 0; i < oldRow.getTableCells().size(); i++) {
cell = newRow.createCell();
CTTcPr ctTcPr = cell.getCTTc().addNewTcPr();
CTTblWidth cellWidth = ctTcPr.addNewTcW();
cellWidth.setType(oldRow.getCell(i).getCTTc().getTcPr().getTcW().getType()); // sets type of width
BigInteger width = oldRow.getCell(i).getCTTc().getTcPr().getTcW().getW();
cellWidth.setW(width); // sets width
if (oldRow.getCell(i).getCTTc().getTcPr().getGridSpan() != null) {
ctTcPr.setGridSpan(oldRow.getCell(i).getCTTc().getTcPr().getGridSpan()); // sets grid span if any
}
XWPFRun run = cell.getParagraphs().get(0).createRun();
run.setText("NewRow C" + i);
}
doc.write(new FileOutputStream("result.docx"));
doc.close();
System.out.println("Done");
}
}
The result.docx looks like: