JTable weird behavior of getAccessibleChild () method leading to null pointer in client code

Question

I came across the strange behavior of JTable (JDK 1.5_22):
After changing the selection in the table and under some unknown specific circumstances, JTable will call the cell renderer with "null" for the value parameter.
This will ultimately lead to a good “Null Pointer Exception” in the code of the user renderer that is not ready for such rude calls.

Here is the culpable method (JTable.java, line 5319):

public Accessible getAccessibleChild(int i) {
            if (i < 0 || i >= getAccessibleChildrenCount()) {
                return null;
            } else {
                // children increase across, and then down, for tables
                // (arbitrary decision)
                int column = getAccessibleColumnAtIndex(i);
                int row = getAccessibleRowAtIndex(i);

                TableColumn aColumn = getColumnModel().getColumn(column);
                TableCellRenderer renderer = aColumn.getCellRenderer();
                if (renderer == null) {
                    Class<?> columnClass = getColumnClass(column);
                    renderer = getDefaultRenderer(columnClass);
                }
                Component component = renderer.getTableCellRendererComponent(
                                  JTable.this, null, false, false,
                                  row, column);
                return new AccessibleJTableCell(JTable.this, row, column,
                      getAccessibleIndexAt(row, column));
            }
        }

and here the main focus is on the erroneous statement:

Component component = renderer.getTableCellRendererComponent(
                                  JTable.this, null, false, false,
                                  row, column);

Asking google whith "JTable getAccessibleChild 5334" was interesting: I'm not alone to meet this "feature." But there was no answer.

.

- ?

Answer 1

EDT. JTable getTableCellRendererComponent .

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Answer 2

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