From time to time I visit the Eclipse news groups to find a solution to a problem I am having with a particular area of Eclipse. Since Eclipse is such a huge platform with many projects there are many different news groups, each designed to cover a particular project or API (Application Programming Interface).
Some of my favorite Eclipse news groups are:
eclipse.platform
eclipse.platform.rcp
eclipse.platform.swt
Often while I am looking for answers in a news group I run across questions that I have already conquered and so I try to give back and help others. Recently I responded to a question about how to perform in-line editing within the cell of an SWT (Standard Widget Toolkit) table. I have included my example java program below. If you are a Java developer and somewhat familiar with SWT/JFace then you should have no problems understanding the example code. If you are new to SWT/JFace I have provided a brief summary of the primary components used to create the example.
Looking at the java code below you will see that the program contains a main method to launch the java program. The primary UI component is an SWT Table which is added to an SWT Composite. Under the table I have added SWT buttons to “Add” and “Remove” rows from the table. The SelectionListeners on the buttons handle the add and remove actions. The model for the table is a POJO (Plain Old Java Object) which I have named “Row”. A TableContentProvider and TableLabelProvider provide the content and labels for the table and the TextCellEditor provides the ability to edit the table allowing a user to type data directly into the table’s cells.
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import org.eclipse.jface.viewers.CellEditor;
import org.eclipse.jface.viewers.ColumnWeightData;
import org.eclipse.jface.viewers.ICellModifier;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.ITableLabelProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.TableLayout;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.TextCellEditor;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;
import org.eclipse.swt.widgets.TableItem;
/**
* This is an example program showing how to use a TableCellEditor
* to allow direct editing of a table's cell.
*
* @author Shawn Spiars
*
*/
public class TableCellModifierExample {
private Table table;
private TableViewer tableViewer;
private final static String[] COLUMN_HEADINGS = {"Property",
"Value"};
public static void main(String [] args) {
new TableCellModifierExample();
}
public TableCellModifierExample() {
Display display = new Display();
Shell shell = new Shell(display, SWT.SHELL_TRIM);
shell.setText("TableCellModifier Example");
shell.setLayout(new FillLayout());
createContents(shell);
shell.setSize(400, 400);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) display.sleep();
}
display.dispose();
}
protected Control createContents(Composite parent) {
Composite composite = new Composite(parent, SWT.NONE);
GridLayout layout = new GridLayout(1, false);
layout.verticalSpacing = 10;
composite.setLayout(layout);
GridData data = new GridData(GridData.FILL_BOTH);
data.grabExcessHorizontalSpace = true;
composite.setLayoutData(data);
table = new Table(composite, SWT.BORDER | SWT.V_SCROLL
| SWT.MULTI | SWT.FULL_SELECTION);
table.setLinesVisible(true);
table.setHeaderVisible(true);
data = new GridData(SWT.FILL, SWT.FILL, true, false);
data.heightHint = 300;
table.setLayoutData(data);
TableLayout tableLayout = new TableLayout();
table.setLayout(tableLayout);
tableLayout.addColumnData(new ColumnWeightData(10, 100,
true));
TableColumn column = new TableColumn(table, SWT.NONE);
column.setText(COLUMN_HEADINGS[0]);
column.setAlignment(SWT.LEFT);
tableLayout.addColumnData(new ColumnWeightData(15, 200,
true));
column = new TableColumn(table, SWT.NONE);
column.setText(COLUMN_HEADINGS[1]);
column.setAlignment(SWT.LEFT);
tableViewer = new TableViewer(table);
tableViewer.setColumnProperties(COLUMN_HEADINGS);
tableViewer.setContentProvider(new
TableContentProvider());
tableViewer.setLabelProvider(new TableLabelProvider());
CellEditor[] editors = new CellEditor[2];
editors[0] = new TextCellEditor(table);
editors[1] = new TextCellEditor(table);
tableViewer.setCellEditors(editors);
tableViewer.setCellModifier(new TableCellModifier());
Composite buttonComposite = new Composite(composite,
SWT.NONE);
FillLayout fillLayout = new FillLayout(SWT.HORIZONTAL);
fillLayout.spacing = 10;
buttonComposite.setLayout(fillLayout);
Button addButton = new Button(buttonComposite,
SWT.PUSH);
addButton.setText("Add");
addButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
Row row = new Row("", "");
tableViewer.add(row);
table.setTopIndex(table.getItemCount());
table.select(table.getItemCount()-1);
tableViewer.editElement(row, 0);
}
});
Button removeButton = new Button(buttonComposite,
SWT.PUSH);
removeButton.setText("Remove");
removeButton.addSelectionListener(new
SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
ISelection selection =
tableViewer.getSelection();
if (selection instanceof
IStructuredSelection) {
Iterator iterator =
((IStructuredSelection)selection).iterator();
while(iterator.hasNext()) {
Object obj = iterator.next();
tableViewer.remove(obj);
}
}
}
});
return composite;
}
public class TableLabelProvider extends LabelProvider
implements ITableLabelProvider {
public Image getColumnImage(Object element, int
columnIndex) {
return null;
}
public String getColumnText(Object element,
int columnIndex) {
Row row = (Row) element;
switch
(columnIndex) {
case 0:
return row.getKey();
case 1:
return row.getValue();
}
return null;
}
}
public class TableContentProvider implements
IStructuredContentProvider {
public Object[] getElements(Object parent) {
List results = new ArrayList();
if (parent instanceof ArrayList) {
results = (ArrayList) parent;
}
return results.toArray();
}
public void dispose() {
}
public void inputChanged(Viewer viewer, Object oldInput,
Object newInput) {
}
}
class TableCellModifier implements ICellModifier {
public boolean canModify(Object element,
String property) {
return true;
}
public Object getValue(Object element,
String property) {
Object result = null;
Row row = (Row) element;
List list = Arrays.asList(COLUMN_HEADINGS);
int columnIndex = list.indexOf(property);
switch (columnIndex) {
case 0:
result = row.getKey();
break;
case 1:
result = row.getValue();
break;
}
return result;
}
public void modify(Object element, String property,
Object value) {
List list = Arrays.asList(COLUMN_HEADINGS);
int columnIndex = list.indexOf(property);
TableItem tableItem = (TableItem) element;
Row row = (Row) tableItem.getData();
switch (columnIndex) {
case 0:
String key = (String) value;
if (key.length() > 0) {
row.setKey(key);
}
break;
case 1:
String v = (String) value;
if (v.length() > 0) {
row.setValue(v);
}
break;
}
tableViewer.update(row, null);
}
}
private class Row {
private String key;
private String value;
public Row(String key, String value) {
setKey(key);
setValue(value);
}
public void setKey(String key) {
this.key = key
}
public String getKey() {
return key;
}
public void setValue(String value) {
this.value = value;
}
public String getValue() {
return value;
}
}
}
In SWTJFace, SWT, Standard Widget Toolkit, Eclipse
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year there were a lot more technical sessions to choose from and overall the presentations seemed more professional than in the previous years. I also liked that the Monday tutorials were included in the overall conference registration fee, rather than an extra charge.