enumcols.html
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<TITLE>Enumerating the Columns in a JTable Component
(Java Developers Almanac Example)
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<h3>
e915.
Enumerating the Columns in a JTable Component</h3>
Column information such as the name of a column and the cell renderer
are kept in a <code>TableColumn</code> object. The values in a column are not
kept in a <code>TableColumn</code> object; they are kept in a <code>TableModel</code>
object. There is one <code>TableColumn</code> object for each visible column.
All the <code>TableColumn</code> objects in a <code>JTable</code> are maintained by a
single <code>TableColumnModel</code> object kept by the <code>JTable</code> component.
<P>
This example demonstrates how to enumerate <code>TableColumn</code> objects in both
model order (order of creation) and view order (modifiable by the
user).
<P> Note: The number of columns in a <code>TableModel</code> can be greater
than the number of <code>TableColumns</code>. The reason is that if you remove
a column from a <code>JTable</code> (or <code>TableColumnModel</code>), you are only
removing the visual representation of the column; the column of data
still exists in the <code>TableModel</code>.
<pre>
// Returns the visible columns in the order that they appear in the model
public TableColumn[] getColumnsInModel(JTable table) {
java.util.List result = new ArrayList();
Enumeration enum = table.getColumnModel().getColumns();
for (; enum.hasMoreElements(); ) {
result.add((TableColumn)enum.nextElement());
}
// Sort the columns based on the model index
Collections.sort(result, new Comparator() {
public int compare(Object a, Object b) {
TableColumn c1 = (TableColumn)a;
TableColumn c2 = (TableColumn)b;
if (c1.getModelIndex() < c2.getModelIndex()) {
return -1;
} else if (c1.getModelIndex() == c2.getModelIndex()) {
return 0;
} else {
return 1;
}
}
});
return (TableColumn[])result.toArray(new TableColumn[result.size()]);
}
// Returns the columns in the order that they appear in the view
public TableColumn[] getColumnsInView(JTable table) {
TableColumn[] result = new TableColumn[table.getColumnCount()];
// Use an enumeration
Enumeration enum = table.getColumnModel().getColumns();
for (int i=0; enum.hasMoreElements(); i++) {
result[i] = (TableColumn)enum.nextElement();
}
// Use a for loop
for (int c=0; c<table.getColumnCount(); c++) {
result[c] = table.getColumnModel().getColumn(c);
}
return result;
}
// Returns the TableColumn associated with the specified column
// index in the model
public TableColumn findTableColumn(JTable table, int columnModelIndex) {
Enumeration enum = table.getColumnModel().getColumns();
for (; enum.hasMoreElements(); ) {
TableColumn col = (TableColumn)enum.nextElement();
if (col.getModelIndex() == columnModelIndex) {
return col;
}
}
return null;
}
</pre>
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Related Examples
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</table>
e914. <a class="eglink" href="ConvertColIndex.html?l=rel">
Converting a Column Index Between the View and Model in a JTable Component
</a>
<br>
e916. <a class="eglink" href="ColSize.html?l=rel">
Setting the Width of a Column in a JTable Component
</a>
<br>
e917. <a class="eglink" href="ColResize.html?l=rel">
Setting the Column Resize Mode of a JTable Component
</a>
<br>
e918. <a class="eglink" href="LockCol.html?l=rel">
Locking the Width of a Column in a JTable Component
</a>
<br>
e919. <a class="eglink" href="AppendCol.html?l=rel">
Appending a Column to a JTable Component
</a>
<br>
e920. <a class="eglink" href="InsertCol.html?l=rel">
Inserting a Column in a JTable Component
</a>
<br>
e921. <a class="eglink" href="RemCol.html?l=rel">
Removing a Column from a JTable Component
</a>
<br>
e922. <a class="eglink" href="MoveCol.html?l=rel">
Moving a Column in a JTable Component
</a>
<br>
e923. <a class="eglink" href="NoHeadMove.html?l=rel">
Allowing the User to Move a Column in a JTable Component
</a>
<br>
e924. <a class="eglink" href="NoResizeHead.html?l=rel">
Allowing the User to Resize a Column in a JTable Component
</a>
<br>
<table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
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See also:
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Cells">
Cells
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Column%20Heads">
Column Heads
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Editing">
Editing
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Events">
Events
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Layout">
Layout
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Rows">
Rows
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Scrolling">
Scrolling
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Selection">
Selection
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Sorting">
Sorting
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Table%20Model">
Table Model
</a>
<a class="eglink" href="/egs/javax.swing.table/pkg.html?l=rel#Tool%20Tips">
Tool Tips
</a>
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