Who’s On Phirst

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;
            }
      }

}