JTreeTable的动态列

Question

I am building a JTreeTable. I found some starter code and have come pretty far. In the end my goal is to be able to have different data at different levels like a hierarchical list.

Currently, I have it working with data at different levels. However, I am running up against a wall when it comes to changing the columns as a next goal. From where I currently stand I have 3 more milestones:

• Show different set of columns for different levels
• Ability to adjust column widths for different levels
• Ensure the JTree part of the table always stays to left

I am getting close to closing out this task but again stuck at the first of these 3.

Since creating a JTreeTable is complex, the minimum example leverages several class listed below in the image:

I am happy to post the code to any of those classes but I also did not want clog the question with useless code. First let me show the functionality I want.

The first image is when the top level is selected and the second image is when the second level is selected. Notice how the columns are different. That is what I want to happen in my application.

Top level selected:

Second level selected:

So one way I tried to solve this problem, is when the list selection is changed inside this section of code:

ListSelectionListener listener = (ListSelectionEvent e) -> {
        TreeTableModelAdapter adapter = (TreeTableModelAdapter) JTreeTable.this.getModel();
        //Need to see why this breaks.
        JTreeTable.this.getTableHeader().setColumnModel(adapter.getColumnModel());
    };
    this.getSelectionModel().addListSelectionListener(listener);

This code is in the initialization of the JTreeTable. I have tried setting the column model on both the TableHeader and the table as well. Below is what happens then when I select a row:

The columns just disappear on me. The creation of the column model is happening in the TreeTableModelAdapter class with the following method:

public TableColumnModel getColumnModel(){
     DefaultTableColumnModel model  = new DefaultTableColumnModel();
     for(int i=0;i<getColumnCount();i++){
         TableColumn column = new TableColumn();
         column.setIdentifier(getColumnName(i));
         model.addColumn(column);
     }
     return model;
 }

Any direction would be very helpful. Again happy to post any code you think could be helpful to answer the question. Just put a comment in and I will add it right away.

Answer 1

I will add the milestones as I find them in case this helps others, but for now this question is answered.

Milestone 1

I was actually able to solve the first milestone. The key is to trigger the creation of the columns of the column model, not to create a new column model. Below is the code for when the row selection is changed:

//Change columns depending on row
ListSelectionListener listener = (ListSelectionEvent e) -> {
    createDefaultColumnsFromModel();
};
this.getSelectionModel().addListSelectionListener(listener);

This code creates the columns based on the row selected in the JTree part of the JTreeTable . The TreeTableModelAdapter implements the getColumnCount() and getColumnName() methods by also passing the selected row in the JTree to the JTreeTableModel so that the columns and their names are dynamically retrieved based on a particular node in the JTree . The key for this for me was trigger those to be called again to update the JTreeTable .

Milestone 2

Adjusting column widths based on the data level proved to be much more difficult than I had originally anticipated. In order to retain the cells state when the column model changed I had to disconnect the painting of the cells from it. This is a hairy process because this is done inside BasicTableUI and the method that gets the rectangle of the cell is private. So I had to subclass it, overload the paint() method and create my own methods that get called inside the paint method. There was a lot of copy pasting so that I could call normally private methods. I just renamed them and referenced these methods instead. The way the ui class was designed did not make it very flexible. Below is 2 images where I am selecting different levels and the columns are obviously different widths at different levels.

Milestone 3

I was able to make this work by keeping track of the view in the model. This seems very dirty to me as the model should separated from the view. Since the tree column's class is unique, I just returned the right class if that column was the first in the view.

The one problem I have with this technique is that I get unexpected behavior where the value returned is not consistent. I attempted to resolve this by overriding JTree.covertValueToText() . Since a JTree only expects 1 value and depending on the sequence of columns in the view this value could change. So in overriding this method I check the stored index for the JTree column's value. Again this causes the unexpected behavior. I will update the post if I find the fix.