Javafx : Restrict Column rearrangement on drag and drop - javafx

Question

In a tree table view, we can re-arrange the columns by dragging the column headers.
I want to restrict the user from dragging the first column alone. Which means my first column should be the first column all the time.
Is this possible?
Thanks in advance.

Answer 1

This is a simple example where I am storing the column arrangement in a temporary list and when ever we are trying to move or replace the first column we are resetting the column arrangement.
!change.getList().get(0).equals(col1)
checks if the col1 is still at the first location after the change. If not, we replace it with the old list.
MCVE
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.stage.Stage;
public class FixFiestColumnTable extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage stage) {
final TableView tableView = new TableView();
TableColumn col1 = new TableColumn("Col 1");
TableColumn col2 = new TableColumn("Col 2");
TableColumn col3 = new TableColumn("Col 3");
tableView.getColumns().setAll(col1, col2, col3);
tableView.getColumns().addListener(new ListChangeListener() {
public ObservableList<TableColumn> tempList = FXCollections.observableArrayList();
#Override
public void onChanged(Change change) {
change.next();
if (change.wasReplaced() && !change.getList().get(0).equals(col1)) {
tableView.getColumns().setAll(tempList);
}
tempList.setAll(change.getList());
}
});
stage.setScene(new Scene(tableView));
stage.show();
}
}

Answer 2

There's no API for that. A solution according to this post is to revert the changes using a ChangeListener.
In your case you'd have to check if the 1st column changes and only revert then.
Here's an example:
import java.util.ArrayList;
import java.util.List;
import javafx.application.Application;
import javafx.collections.ListChangeListener;
import javafx.scene.Scene;
import javafx.scene.control.TreeTableColumn;
import javafx.scene.control.TreeTableView;
import javafx.stage.Stage;
public class TreeTableTest extends Application {
#SuppressWarnings({ "unchecked", "rawtypes" })
#Override
public void start(Stage stage) {
final TreeTableView treeTableView = new TreeTableView();
TreeTableColumn c1 = new TreeTableColumn("1");
TreeTableColumn c2 = new TreeTableColumn("2");
TreeTableColumn c3 = new TreeTableColumn("3");
TreeTableColumn c4 = new TreeTableColumn("4");
treeTableView.getColumns().setAll(c1, c2, c3, c4);
treeTableView.getColumns().addListener(new ListChangeListener() {
public boolean suspended;
#Override
public void onChanged(Change change) {
change.next();
if (change.wasReplaced() && !suspended) {
List<TreeTableColumn> oldList = new ArrayList<>(change.getRemoved());
List<TreeTableColumn> newList = new ArrayList<>(treeTableView.getColumns());
// first column changed => revert to original list
if (oldList.get(0) != newList.get(0)) {
this.suspended = true;
treeTableView.getColumns().setAll(oldList);
this.suspended = false;
}
}
}
});
stage.setScene(new Scene(treeTableView));
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}