JavaFX TreeView TreeColumn auto-size to fit content

After 3 years I come back to this problem again, some suggestions are calculating the size of text of data in each cell (it's complicated depending on font size, font family, padding...)

But I realize that when I click on the divider on table header, it's resized fit to content as I want. So I dig into JavaFX source code I finally found resizeColumnToFitContent method in TableViewSkin, but it is protected method, we can resolve by reflection:

import com.sun.javafx.scene.control.skin.TableViewSkin;
import javafx.scene.control.Skin;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class GUIUtils {
    private static Method columnToFitMethod;

    static {
        try {
            columnToFitMethod = TableViewSkin.class.getDeclaredMethod("resizeColumnToFitContent", TableColumn.class, int.class);
            columnToFitMethod.setAccessible(true);
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
    }

    public static void autoFitTable(TableView tableView) {
        tableView.getItems().addListener(new ListChangeListener<Object>() {
            @Override
            public void onChanged(Change<?> c) {
                for (Object column : tableView.getColumns()) {
                    try {
                        columnToFitMethod.invoke(tableView.getSkin(), column, -1);
                    } catch (IllegalAccessException | InvocationTargetException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
    }
}

Note that we call "tableView.getItems()" so we have to call this function after setItems()

If a column is set to AutoSize, PHPExcel attempts to calculate the column width based on the calculated value of the column (so on the result of any formulae), and any additional characters added by format masks such as thousand separators.

By default, this is an estimated width: a more accurate calculation method is available, based on using GD, which can also handle font style features such as bold and italic; but this is a much bigger overhead, so it is turned off by default. You can enable the more accurate calculation using

PHPExcel_Shared_Font::setAutoSizeMethod(PHPExcel_Shared_Font::AUTOSIZE_METHOD_EXACT);

However, autosize doesn't apply to all Writer formats... for example CSV. You don't mention what writer you're using.

But you also need to identify the columns to set dimensions:

foreach(range('B','G') as $columnID) {
    $objPHPExcel->getActiveSheet()->getColumnDimension($columnID)
        ->setAutoSize(true);
}

$objPHPExcel->getActiveSheet()->getColumnDimension() expects a column ID.

$objPHPExcel->getActiveSheet()->getColumnDimensions() will return an array of all the defined column dimension records; but unless a column dimension record has been explicitly created (perhaps by loading a template, or by manually calling getColumnDimension()) then it won't exist (memory saving).