Moving a Row in a JTable Component
To move a row of data to a JTable component, you need to move it
in its table model. A simple implementation of a table model that
supports the moving of row data is DefaultTableModel.
When moving one or more rows using
DefaultTableModel.moveRow(), the set of the rows to be moved and
the destination position must be specified. The contiguous set of rows
to be moved is specified with the index of the starting row and the
index of the end row. Row indices start from 0. For example, if
there are 2 rows in a table, the index of the first row is 0 and the
index of the second row is 1.
The destination is also a position. Positions are locations between
rows. For example, if there are 2 rows in a table, there are 3
possible positions – – 0, 1,and 2. The important thing to remember about
the destination position is that it specifies the position in the row
data after the rows to be moved are taken out of the row
data. For example, if you want to move the first row to the end of the
table, the destination position is not getRowCount(), it is
getRowCount()-1. Similarly, if you want to move the first 2
lines to the end of the table, the destination position is
getRowCount()-2.
The way in which the parameters are interpreted is somewhat
awkward. The more conventional method is to either make the end index
exclusive (like String.substring()) or replace end with a
length. Also, it is easier to specify the destination as it exists
before the operation, and not have to pretend that the rows to be
moved are taken out. A version of moveRow() with more
conventional parameter interpretation is provided in
betterMoveRow().
DefaultTableModel model = new DefaultTableModel();
JTable table = new JTable(model);
// Create some data
model.addColumn("Col1");
model.addRow(new Object[]{"r1"});
model.addRow(new Object[]{"r2"});
model.addRow(new Object[]{"r3"});
// Move the first row to the end of the table
model.moveRow(0, 0, model.getRowCount()-1);
betterMoveRow(model, 0, 1, model.getRowCount());
// Move the last row to the beginning of the table
model.moveRow(model.getRowCount()-1, model.getRowCount()-1, 0);
betterMoveRow(model, model.getRowCount()-1, model.getRowCount(), 0);
// Move the first two rows to the end of the table
model.moveRow(0, 1, model.getRowCount()-2);
betterMoveRow(model, 0, 2, model.getRowCount());
// Move the last two rows to the start of the table
model.moveRow(model.getRowCount()-2, model.getRowCount()-1, 0);
betterMoveRow(model, model.getRowCount()-2, model.getRowCount(), 0);
// A better version of moveRow().
// Moves all rows contained between the positions start and end
// to the position specified by dest.
public static void betterMoveRow(DefaultTableModel model, int start, int end, int dest) {
int count = end - start;
if (count <= 0) {
return;
}
if (dest > start) {
dest = Math.max(start, dest-count);
}
end--;
model.moveRow(start, end, dest);
}
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