java.lang.UnsupportedOperationException from Grid

Flow
1

I’m getting this below exception

Caused by: java.lang.UnsupportedOperationException
    at java.base/java.util.Collections$UnmodifiableList.add(Collections.java:1352)
``` and is caused by lines

grid.getColumns()
.remove(grid.getColumns().size() - 1);
grid.getColumns()
.add(0,rowIndex);


My objective is to move the last column to the first column. I see ``setColumnOrder`` method is available to reorder the columns but it needs individual columns. I do not want to create the columns manually and later add it to ``setColumnOrder``. Please let me know how can I reorder the columns?
![image.png|3236x467](upload://jEYKwdkr6gJio2wrCVXbHs33WAD.png)
2

I need the ID column to displayFirst
image.png

3

In the docs, under Components > Grid > Column Reordering & Resizing, the code shows:

 grid.setColumnReorderingAllowed(true);

I figure if it allows DnD functions like this, then it should be allowable/possible to do it programmatically too. Unfortunately, the code example doesn’t show this.

4

You can’t modify the result of getColumns, the list is unmodifiable. You can use this list and create a copy in the order you want then call setColumnOrder

5

Let me try. And another question, when the list is unmodifiable, why there are remove/add methods?

6

The returned instance list is unmodifiable, that’s why there are add/remove methods (Java lists don’t notify on changes)

7

I created a copy like this ```final List<Grid.Column> columnList = grid.getColumns();
columnList.remove(columnList.size() - 1);
columnList.add(0, rowIndex);

    grid.setColumnOrder(columnList);```. But still getting the same exception. What am I doing wrong ?
8

I think is what you meant ```final List<Grid.Column> columnList = new ArrayList<>();
columnList.addAll(grid.getColumns());
columnList.remove(columnList.size() - 1);
columnList.add(0, rowIndex);

    grid.setColumnOrder(columnList);```. This one worked
9

image.png

10

Yes, the first wasn’t a copy