#3755 Select threw IllegalArgumentException when browsing pages quickly

svn changeset:10012/svn branch:6.2

1 files changed, 435 insertions, 428 deletions

diff --git a/src/com/vaadin/ui/Select.java b/src/com/vaadin/ui/Select.java
index af812e4abb..48877d00f1 100644
--- a/src/com/vaadin/ui/Select.java
+++ b/src/com/vaadin/ui/Select.java
@@ -24,13 +24,13 @@ import com.vaadin.terminal.gwt.client.ui.VFilterSelect;
  * set of choices is presented as a set of {@link com.vaadin.data.Item}s in a
  * {@link com.vaadin.data.Container}.
  * </p>
- * 
+ *
  * <p>
  * A <code>Select</code> component may be in single- or multiselect mode.
  * Multiselect mode means that more than one item can be selected
  * simultaneously.
  * </p>
- * 
+ *
  * @author IT Mill Ltd.
  * @version
  * @VERSION@
@@ -40,431 +40,438 @@ import com.vaadin.terminal.gwt.client.ui.VFilterSelect;
 @ClientWidget(VFilterSelect.class)
 public class Select extends AbstractSelect implements AbstractSelect.Filtering {
 
-	/**
-	 * Holds value of property pageLength. 0 disables paging.
-	 */
-	protected int pageLength = 10;
-
-	private int columns = 0;
-
-	// Current page when the user is 'paging' trough options
-	private int currentPage = -1;
-
-	private int filteringMode = FILTERINGMODE_STARTSWITH;
-
-	private String filterstring;
-	private String prevfilterstring;
-	private List filteredOptions;
-
-	/**
-	 * Flag to indicate that request repaint is called by filter request only
-	 */
-	private boolean optionRequest;
-
-	/* Constructors */
-
-	/* Component methods */
-
-	public Select() {
-		super();
-	}
-
-	public Select(String caption, Collection options) {
-		super(caption, options);
-	}
-
-	public Select(String caption, Container dataSource) {
-		super(caption, dataSource);
-	}
-
-	public Select(String caption) {
-		super(caption);
-	}
-
-	/**
-	 * Paints the content of this component.
-	 * 
-	 * @param target
-	 *            the Paint Event.
-	 * @throws PaintException
-	 *             if the paint operation failed.
-	 */
-	@Override
-	public void paintContent(PaintTarget target) throws PaintException {
-		if (isMultiSelect()) {
-			// background compatibility hack. This object shouldn't be used for
-			// multiselect lists anymore (ListSelect instead). This fallbacks to
-			// a simpler paint method in super class.
-			super.paintContent(target);
-			return;
-		}
-
-		// clear caption change listeners
-		getCaptionChangeListener().clear();
-
-		// The tab ordering number
-		if (getTabIndex() != 0) {
-			target.addAttribute("tabindex", getTabIndex());
-		}
-
-		// If the field is modified, but not committed, set modified attribute
-		if (isModified()) {
-			target.addAttribute("modified", true);
-		}
-
-		// Adds the required attribute
-		if (isRequired()) {
-			target.addAttribute("required", true);
-		}
-
-		if (isNewItemsAllowed()) {
-			target.addAttribute("allownewitem", true);
-		}
-
-		boolean needNullSelectOption = false;
-		if (isNullSelectionAllowed()) {
-			target.addAttribute("nullselect", true);
-			needNullSelectOption = (getNullSelectionItemId() == null);
-			if (!needNullSelectOption) {
-				target.addAttribute("nullselectitem", true);
-			}
-		}
-
-		// Constructs selected keys array
-		String[] selectedKeys;
-		if (isMultiSelect()) {
-			selectedKeys = new String[((Set) getValue()).size()];
-		} else {
-			selectedKeys = new String[(getValue() == null
-					&& getNullSelectionItemId() == null ? 0 : 1)];
-		}
-
-		target.addAttribute("pagelength", pageLength);
-
-		target.addAttribute("filteringmode", getFilteringMode());
-
-		// Paints the options and create array of selected id keys
-		// TODO Also use conventional rendering if lazy loading is not supported
-		// by terminal
-		int keyIndex = 0;
-
-		target.startTag("options");
-
-		if (currentPage < 0) {
-			optionRequest = false;
-			currentPage = 0;
-			filterstring = "";
-		}
-
-		List options = getFilteredOptions();
-		options = sanitetizeList(options, needNullSelectOption);
-
-		final boolean paintNullSelection = needNullSelectOption
-				&& (currentPage == 0 && (getFilteringMode() == FILTERINGMODE_OFF
-						|| filterstring == null || filterstring.equals("")));
-
-		if (paintNullSelection) {
-			target.startTag("so");
-			target.addAttribute("caption", "");
-			target.addAttribute("key", "");
-			target.endTag("so");
-		}
-
-		final Iterator i = options.iterator();
-		// Paints the available selection options from data source
-
-		while (i.hasNext()) {
-
-			final Object id = i.next();
-
-			if (!isNullSelectionAllowed() && id != null
-					&& id.equals(getNullSelectionItemId()) && !isSelected(id)) {
-				continue;
-			}
-
-			// Gets the option attribute values
-			final String key = itemIdMapper.key(id);
-			final String caption = getItemCaption(id);
-			final Resource icon = getItemIcon(id);
-			getCaptionChangeListener().addNotifierForItem(id);
-
-			// Paints the option
-			target.startTag("so");
-			if (icon != null) {
-				target.addAttribute("icon", icon);
-			}
-			target.addAttribute("caption", caption);
-			if (id != null && id.equals(getNullSelectionItemId())) {
-				target.addAttribute("nullselection", true);
-			}
-			target.addAttribute("key", key);
-			if (isSelected(id) && keyIndex < selectedKeys.length) {
-				target.addAttribute("selected", true);
-				selectedKeys[keyIndex++] = key;
-			}
-			target.endTag("so");
-		}
-		target.endTag("options");
-
-		target.addAttribute("totalitems", size()
-				+ (needNullSelectOption ? 1 : 0));
-		if (filteredOptions != null) {
-			target.addAttribute("totalMatches", filteredOptions.size()
-					+ (needNullSelectOption ? 1 : 0));
-		}
-
-		// Paint variables
-		target.addVariable(this, "selected", selectedKeys);
-		if (isNewItemsAllowed()) {
-			target.addVariable(this, "newitem", "");
-		}
-
-		target.addVariable(this, "filter", filterstring);
-		target.addVariable(this, "page", currentPage);
-
-		currentPage = -1; // current page is always set by client
-
-		optionRequest = true;
-	}
-
-	/**
-	 * Makes correct sublist of given list of options.
-	 * 
-	 * If paint is not an option request (affected by page or filter change),
-	 * page will be the one where possible selection exists.
-	 * 
-	 * Detects proper first and last item in list to return right page of
-	 * options.
-	 * 
-	 * @param options
-	 * @param needNullSelectOption
-	 *            flag to indicate if nullselect option needs to be taken into
-	 *            consideration
-	 */
-	private List sanitetizeList(List options, boolean needNullSelectOption) {
-
-		if (options.size() > pageLength) {
-			int first = currentPage * pageLength;
-			int last = first + pageLength;
-			if (needNullSelectOption) {
-				if (currentPage > 0) {
-					first--;
-				}
-				last--;
-			}
-			if (options.size() < last) {
-				last = options.size();
-			}
-			if (!optionRequest) {
-				// TODO ensure proper page
-				if (!isMultiSelect()) {
-					Object selection = getValue();
-					if (selection != null) {
-						int index = options.indexOf(selection);
-						if (index != -1 && (index < first || index >= last)) {
-							int newPage = (index + (needNullSelectOption ? 1
-									: 0))
-									/ pageLength;
-							currentPage = newPage;
-							return sanitetizeList(options, needNullSelectOption);
-						}
-					}
-				}
-			}
-
-			return options.subList(first, last);
-		} else {
-			return options;
-		}
-	}
-
-	protected List getFilteredOptions() {
-		if (filterstring == null || filterstring.equals("")
-				|| filteringMode == FILTERINGMODE_OFF) {
-			prevfilterstring = null;
-			filteredOptions = new LinkedList(getItemIds());
-			return filteredOptions;
-		}
-
-		if (filterstring.equals(prevfilterstring)) {
-			return filteredOptions;
-		}
-
-		Collection items;
-		if (prevfilterstring != null
-				&& filterstring.startsWith(prevfilterstring)) {
-			items = filteredOptions;
-		} else {
-			items = getItemIds();
-		}
-		prevfilterstring = filterstring;
-
-		filteredOptions = new LinkedList();
-		for (final Iterator it = items.iterator(); it.hasNext();) {
-			final Object itemId = it.next();
-			String caption = getItemCaption(itemId);
-			if (caption == null || caption.equals("")) {
-				continue;
-			} else {
-				caption = caption.toLowerCase();
-			}
-			switch (filteringMode) {
-			case FILTERINGMODE_CONTAINS:
-				if (caption.indexOf(filterstring) > -1) {
-					filteredOptions.add(itemId);
-				}
-				break;
-			case FILTERINGMODE_STARTSWITH:
-			default:
-				if (caption.startsWith(filterstring)) {
-					filteredOptions.add(itemId);
-				}
-				break;
-			}
-		}
-
-		return filteredOptions;
-	}
-
-	/**
-	 * Invoked when the value of a variable has changed.
-	 * 
-	 * @see com.vaadin.ui.AbstractComponent#changeVariables(java.lang.Object,
-	 *      java.util.Map)
-	 */
-	@Override
-	public void changeVariables(Object source, Map variables) {
-
-		// Selection change
-		if (variables.containsKey("selected")) {
-			final String[] ka = (String[]) variables.get("selected");
-
-			if (isMultiSelect()) {
-				// Multiselect mode
-
-				// TODO Optimize by adding repaintNotNeeded whan applicaple
-
-				// Converts the key-array to id-set
-				final LinkedList s = new LinkedList();
-				for (int i = 0; i < ka.length; i++) {
-					final Object id = itemIdMapper.get(ka[i]);
-					if (id != null && containsId(id)) {
-						s.add(id);
-					}
-				}
-
-				// Limits the deselection to the set of visible items
-				// (non-visible items can not be deselected)
-				final Collection visible = getVisibleItemIds();
-				if (visible != null) {
-					Set newsel = (Set) getValue();
-					if (newsel == null) {
-						newsel = new HashSet();
-					} else {
-						newsel = new HashSet(newsel);
-					}
-					newsel.removeAll(visible);
-					newsel.addAll(s);
-					setValue(newsel, true);
-				}
-			} else {
-				// Single select mode
-				if (ka.length == 0) {
-
-					// Allows deselection only if the deselected item is visible
-					final Object current = getValue();
-					final Collection visible = getVisibleItemIds();
-					if (visible != null && visible.contains(current)) {
-						setValue(null, true);
-					}
-				} else {
-					final Object id = itemIdMapper.get(ka[0]);
-					if (id != null && id.equals(getNullSelectionItemId())) {
-						setValue(null, true);
-					} else {
-						setValue(id, true);
-					}
-				}
-			}
-		}
-
-		String newFilter;
-		if ((newFilter = (String) variables.get("filter")) != null) {
-			// this is a filter request
-			currentPage = ((Integer) variables.get("page")).intValue();
-			filterstring = newFilter;
-			if (filterstring != null) {
-				filterstring = filterstring.toLowerCase();
-			}
-			optionRepaint();
-			return;
-		}
-
-		// New option entered (and it is allowed)
-		if (isNewItemsAllowed()) {
-			final String newitem = (String) variables.get("newitem");
-			if (newitem != null && newitem.length() > 0) {
-				getNewItemHandler().addNewItem(newitem);
-				// rebuild list
-				filterstring = null;
-				prevfilterstring = null;
-			}
-		}
-
-	}
-
-	@Override
-	public void requestRepaint() {
-		super.requestRepaint();
-		optionRequest = false;
-		prevfilterstring = filterstring;
-		filterstring = null;
-	}
-
-	private void optionRepaint() {
-		super.requestRepaint();
-	}
-
-	public void setFilteringMode(int filteringMode) {
-		this.filteringMode = filteringMode;
-	}
-
-	public int getFilteringMode() {
-		return filteringMode;
-	}
-
-	/**
-	 * Note, one should use more generic setWidth(String) method instead of
-	 * this. This now days actually converts columns to width with em css unit.
-	 * 
-	 * Sets the number of columns in the editor. If the number of columns is set
-	 * 0, the actual number of displayed columns is determined implicitly by the
-	 * adapter.
-	 * 
-	 * @deprecated
-	 * 
-	 * @param columns
-	 *            the number of columns to set.
-	 */
-	@Deprecated
-	public void setColumns(int columns) {
-		if (columns < 0) {
-			columns = 0;
-		}
-		if (this.columns != columns) {
-			this.columns = columns;
-			setWidth(columns, Select.UNITS_EM);
-			requestRepaint();
-		}
-	}
-
-	/**
-	 * @deprecated see setter function
-	 * @return
-	 */
-	@Deprecated
-	public int getColumns() {
-		return columns;
-	}
+    /**
+     * Holds value of property pageLength. 0 disables paging.
+     */
+    protected int pageLength = 10;
+
+    private int columns = 0;
+
+    // Current page when the user is 'paging' trough options
+    private int currentPage = -1;
+
+    private int filteringMode = FILTERINGMODE_STARTSWITH;
+
+    private String filterstring;
+    private String prevfilterstring;
+    private List filteredOptions;
+
+    /**
+     * Flag to indicate that request repaint is called by filter request only
+     */
+    private boolean optionRequest;
+
+    /* Constructors */
+
+    /* Component methods */
+
+    public Select() {
+        super();
+    }
+
+    public Select(String caption, Collection options) {
+        super(caption, options);
+    }
+
+    public Select(String caption, Container dataSource) {
+        super(caption, dataSource);
+    }
+
+    public Select(String caption) {
+        super(caption);
+    }
+
+    /**
+     * Paints the content of this component.
+     *
+     * @param target
+     *            the Paint Event.
+     * @throws PaintException
+     *             if the paint operation failed.
+     */
+    @Override
+    public void paintContent(PaintTarget target) throws PaintException {
+        if (isMultiSelect()) {
+            // background compatibility hack. This object shouldn't be used for
+            // multiselect lists anymore (ListSelect instead). This fallbacks to
+            // a simpler paint method in super class.
+            super.paintContent(target);
+            return;
+        }
+
+        // clear caption change listeners
+        getCaptionChangeListener().clear();
+
+        // The tab ordering number
+        if (getTabIndex() != 0) {
+            target.addAttribute("tabindex", getTabIndex());
+        }
+
+        // If the field is modified, but not committed, set modified attribute
+        if (isModified()) {
+            target.addAttribute("modified", true);
+        }
+
+        // Adds the required attribute
+        if (isRequired()) {
+            target.addAttribute("required", true);
+        }
+
+        if (isNewItemsAllowed()) {
+            target.addAttribute("allownewitem", true);
+        }
+
+        boolean needNullSelectOption = false;
+        if (isNullSelectionAllowed()) {
+            target.addAttribute("nullselect", true);
+            needNullSelectOption = (getNullSelectionItemId() == null);
+            if (!needNullSelectOption) {
+                target.addAttribute("nullselectitem", true);
+            }
+        }
+
+        // Constructs selected keys array
+        String[] selectedKeys;
+        if (isMultiSelect()) {
+            selectedKeys = new String[((Set) getValue()).size()];
+        } else {
+            selectedKeys = new String[(getValue() == null
+                    && getNullSelectionItemId() == null ? 0 : 1)];
+        }
+
+        target.addAttribute("pagelength", pageLength);
+
+        target.addAttribute("filteringmode", getFilteringMode());
+
+        // Paints the options and create array of selected id keys
+        // TODO Also use conventional rendering if lazy loading is not supported
+        // by terminal
+        int keyIndex = 0;
+
+        target.startTag("options");
+
+        if (currentPage < 0) {
+            optionRequest = false;
+            currentPage = 0;
+            filterstring = "";
+        }
+
+        List options = getFilteredOptions();
+        options = sanitetizeList(options, needNullSelectOption);
+
+        final boolean paintNullSelection = needNullSelectOption
+                && (currentPage == 0 && (getFilteringMode() == FILTERINGMODE_OFF
+                        || filterstring == null || filterstring.equals("")));
+
+        if (paintNullSelection) {
+            target.startTag("so");
+            target.addAttribute("caption", "");
+            target.addAttribute("key", "");
+            target.endTag("so");
+        }
+
+        final Iterator i = options.iterator();
+        // Paints the available selection options from data source
+
+        while (i.hasNext()) {
+
+            final Object id = i.next();
+
+            if (!isNullSelectionAllowed() && id != null
+                    && id.equals(getNullSelectionItemId()) && !isSelected(id)) {
+                continue;
+            }
+
+            // Gets the option attribute values
+            final String key = itemIdMapper.key(id);
+            final String caption = getItemCaption(id);
+            final Resource icon = getItemIcon(id);
+            getCaptionChangeListener().addNotifierForItem(id);
+
+            // Paints the option
+            target.startTag("so");
+            if (icon != null) {
+                target.addAttribute("icon", icon);
+            }
+            target.addAttribute("caption", caption);
+            if (id != null && id.equals(getNullSelectionItemId())) {
+                target.addAttribute("nullselection", true);
+            }
+            target.addAttribute("key", key);
+            if (isSelected(id) && keyIndex < selectedKeys.length) {
+                target.addAttribute("selected", true);
+                selectedKeys[keyIndex++] = key;
+            }
+            target.endTag("so");
+        }
+        target.endTag("options");
+
+        target.addAttribute("totalitems", size()
+                + (needNullSelectOption ? 1 : 0));
+        if (filteredOptions != null) {
+            target.addAttribute("totalMatches", filteredOptions.size()
+                    + (needNullSelectOption ? 1 : 0));
+        }
+
+        // Paint variables
+        target.addVariable(this, "selected", selectedKeys);
+        if (isNewItemsAllowed()) {
+            target.addVariable(this, "newitem", "");
+        }
+
+        target.addVariable(this, "filter", filterstring);
+        target.addVariable(this, "page", currentPage);
+
+        currentPage = -1; // current page is always set by client
+
+        optionRequest = true;
+    }
+
+    /**
+     * Makes correct sublist of given list of options.
+     *
+     * If paint is not an option request (affected by page or filter change),
+     * page will be the one where possible selection exists.
+     *
+     * Detects proper first and last item in list to return right page of
+     * options. Also, if the current page is beyond the end of the list, it will
+     * be adjusted.
+     *
+     * @param options
+     * @param needNullSelectOption
+     *            flag to indicate if nullselect option needs to be taken into
+     *            consideration
+     */
+    private List sanitetizeList(List options, boolean needNullSelectOption) {
+
+        if (options.size() > pageLength) {
+            int first = currentPage * pageLength;
+            int last = first + pageLength;
+            if (needNullSelectOption) {
+                if (currentPage > 0) {
+                    first--;
+                }
+                last--;
+            }
+            if (options.size() < last) {
+                last = options.size();
+            }
+            if (!optionRequest) {
+                // TODO ensure proper page
+                if (!isMultiSelect()) {
+                    Object selection = getValue();
+                    if (selection != null) {
+                        int index = options.indexOf(selection);
+                        if (index != -1 && (index < first || index >= last)) {
+                            int newPage = (index + (needNullSelectOption ? 1
+                                    : 0))
+                                    / pageLength;
+                            currentPage = newPage;
+                            return sanitetizeList(options, needNullSelectOption);
+                        }
+                    }
+                }
+            }
+
+            // adjust the current page if beyond the end of the list
+            if (first >= last && currentPage > 0) {
+                currentPage -= (first - last + pageLength) / pageLength;
+                return sanitetizeList(options, needNullSelectOption);
+            }
+
+            return options.subList(first, last);
+        } else {
+            return options;
+        }
+    }
+
+    protected List getFilteredOptions() {
+        if (filterstring == null || filterstring.equals("")
+                || filteringMode == FILTERINGMODE_OFF) {
+            prevfilterstring = null;
+            filteredOptions = new LinkedList(getItemIds());
+            return filteredOptions;
+        }
+
+        if (filterstring.equals(prevfilterstring)) {
+            return filteredOptions;
+        }
+
+        Collection items;
+        if (prevfilterstring != null
+                && filterstring.startsWith(prevfilterstring)) {
+            items = filteredOptions;
+        } else {
+            items = getItemIds();
+        }
+        prevfilterstring = filterstring;
+
+        filteredOptions = new LinkedList();
+        for (final Iterator it = items.iterator(); it.hasNext();) {
+            final Object itemId = it.next();
+            String caption = getItemCaption(itemId);
+            if (caption == null || caption.equals("")) {
+                continue;
+            } else {
+                caption = caption.toLowerCase();
+            }
+            switch (filteringMode) {
+            case FILTERINGMODE_CONTAINS:
+                if (caption.indexOf(filterstring) > -1) {
+                    filteredOptions.add(itemId);
+                }
+                break;
+            case FILTERINGMODE_STARTSWITH:
+            default:
+                if (caption.startsWith(filterstring)) {
+                    filteredOptions.add(itemId);
+                }
+                break;
+            }
+        }
+
+        return filteredOptions;
+    }
+
+    /**
+     * Invoked when the value of a variable has changed.
+     *
+     * @see com.vaadin.ui.AbstractComponent#changeVariables(java.lang.Object,
+     *      java.util.Map)
+     */
+    @Override
+    public void changeVariables(Object source, Map variables) {
+
+        // Selection change
+        if (variables.containsKey("selected")) {
+            final String[] ka = (String[]) variables.get("selected");
+
+            if (isMultiSelect()) {
+                // Multiselect mode
+
+                // TODO Optimize by adding repaintNotNeeded whan applicaple
+
+                // Converts the key-array to id-set
+                final LinkedList s = new LinkedList();
+                for (int i = 0; i < ka.length; i++) {
+                    final Object id = itemIdMapper.get(ka[i]);
+                    if (id != null && containsId(id)) {
+                        s.add(id);
+                    }
+                }
+
+                // Limits the deselection to the set of visible items
+                // (non-visible items can not be deselected)
+                final Collection visible = getVisibleItemIds();
+                if (visible != null) {
+                    Set newsel = (Set) getValue();
+                    if (newsel == null) {
+                        newsel = new HashSet();
+                    } else {
+                        newsel = new HashSet(newsel);
+                    }
+                    newsel.removeAll(visible);
+                    newsel.addAll(s);
+                    setValue(newsel, true);
+                }
+            } else {
+                // Single select mode
+                if (ka.length == 0) {
+
+                    // Allows deselection only if the deselected item is visible
+                    final Object current = getValue();
+                    final Collection visible = getVisibleItemIds();
+                    if (visible != null && visible.contains(current)) {
+                        setValue(null, true);
+                    }
+                } else {
+                    final Object id = itemIdMapper.get(ka[0]);
+                    if (id != null && id.equals(getNullSelectionItemId())) {
+                        setValue(null, true);
+                    } else {
+                        setValue(id, true);
+                    }
+                }
+            }
+        }
+
+        String newFilter;
+        if ((newFilter = (String) variables.get("filter")) != null) {
+            // this is a filter request
+            currentPage = ((Integer) variables.get("page")).intValue();
+            filterstring = newFilter;
+            if (filterstring != null) {
+                filterstring = filterstring.toLowerCase();
+            }
+            optionRepaint();
+            return;
+        }
+
+        // New option entered (and it is allowed)
+        if (isNewItemsAllowed()) {
+            final String newitem = (String) variables.get("newitem");
+            if (newitem != null && newitem.length() > 0) {
+                getNewItemHandler().addNewItem(newitem);
+                // rebuild list
+                filterstring = null;
+                prevfilterstring = null;
+            }
+        }
+
+    }
+
+    @Override
+    public void requestRepaint() {
+        super.requestRepaint();
+        optionRequest = false;
+        prevfilterstring = filterstring;
+        filterstring = null;
+    }
+
+    private void optionRepaint() {
+        super.requestRepaint();
+    }
+
+    public void setFilteringMode(int filteringMode) {
+        this.filteringMode = filteringMode;
+    }
+
+    public int getFilteringMode() {
+        return filteringMode;
+    }
+
+    /**
+     * Note, one should use more generic setWidth(String) method instead of
+     * this. This now days actually converts columns to width with em css unit.
+     *
+     * Sets the number of columns in the editor. If the number of columns is set
+     * 0, the actual number of displayed columns is determined implicitly by the
+     * adapter.
+     *
+     * @deprecated
+     *
+     * @param columns
+     *            the number of columns to set.
+     */
+    @Deprecated
+    public void setColumns(int columns) {
+        if (columns < 0) {
+            columns = 0;
+        }
+        if (this.columns != columns) {
+            this.columns = columns;
+            setWidth(columns, Select.UNITS_EM);
+            requestRepaint();
+        }
+    }
+
+    /**
+     * @deprecated see setter function
+     * @return
+     */
+    @Deprecated
+    public int getColumns() {
+        return columns;
+    }
 
 }