org.apache.wicket.markup.html.list.PageableListView.java Source code

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Here is the source code for org.apache.wicket.markup.html.list.PageableListView.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.wicket.markup.html.list;

import java.util.List;

import org.apache.wicket.markup.html.navigation.paging.IPageableItems;
import org.apache.wicket.model.IModel;

/**
 * PageableListView is similar to ListView but provides in addition pageable views. A
 * PageableListView holds pageable rows of information. The rows can be re-ordered and deleted,
 * either one at a time or many at a time.
 * 
 * @author Jonathan Locke
 * @param <T>
 *            type of elements contained in the model's list
 */
public abstract class PageableListView<T> extends ListView<T> implements IPageableItems {
    private static final long serialVersionUID = 1L;

    /** The page to show. */
    private long currentPage;

    /** Number of rows per page of the list view. */
    private long itemsPerPage;

    /**
     * Constructor
     * 
     * @param id
     *            See Component
     * @param model
     *            See Component
     * @param itemsPerPage
     *            Number of rows to show on a page
     */
    public PageableListView(final String id, final IModel<? extends List<T>> model, long itemsPerPage) {
        super(id, model);
        this.itemsPerPage = itemsPerPage;
    }

    /**
     * Creates a pageable list view having the given number of rows per page that uses the provided
     * object as a simple model.
     * 
     * @param id
     *            See Component
     * @param list
     *            See Component
     * @param itemsPerPage
     *            Number of rows to show on a page
     * @see ListView#ListView(String, List)
     */
    public PageableListView(final String id, final List<T> list, final long itemsPerPage) {
        super(id, list);
        this.itemsPerPage = itemsPerPage;
    }

    /**
     * Gets the index of the current page being displayed by this list view.
     * 
     * @return Returns the currentPage.
     */
    @Override
    public final long getCurrentPage() {
        // If first cell is out of range, bring page back into range
        while ((currentPage > 0) && ((currentPage * itemsPerPage) >= getItemCount())) {
            currentPage--;
        }

        return currentPage;
    }

    /**
     * Gets the number of pages in this list view.
     * 
     * @return The number of pages in this list view
     */
    @Override
    public final long getPageCount() {
        return ((getItemCount() + itemsPerPage) - 1) / itemsPerPage;
    }

    /**
     * Gets the maximum number of rows on each page.
     * 
     * @return the maximum number of rows on each page.
     */
    @Override
    public final long getItemsPerPage() {
        return itemsPerPage;
    }

    /**
     * Sets the maximum number of rows on each page.
     * 
     * @param itemsPerPage
     *            the maximum number of rows on each page.
     */
    public final void setItemsPerPage(long itemsPerPage) {
        if (itemsPerPage < 0) {
            itemsPerPage = 0;
        }

        addStateChange();
        this.itemsPerPage = itemsPerPage;
    }

    /**
     * @return offset of first item
     */
    public long getFirstItemOffset() {
        return getCurrentPage() * getItemsPerPage();
    }

    /**
     * @see org.apache.wicket.markup.html.navigation.paging.IPageableItems#getItemCount()
     */
    @Override
    public long getItemCount() {
        return getList().size();
    }

    /**
     * @see org.apache.wicket.markup.html.list.ListView#getViewSize()
     */
    @Override
    public int getViewSize() {
        if (getDefaultModelObject() != null) {
            super.setStartIndex((int) getFirstItemOffset());
            super.setViewSize((int) getItemsPerPage());
        }

        return super.getViewSize();
    }

    /**
     * Sets the current page that this list view should show.
     * 
     * @param currentPage
     *            The currentPage to set.
     */
    @Override
    public final void setCurrentPage(long currentPage) {
        if (currentPage < 0) {
            currentPage = 0;
        }

        long pageCount = getPageCount();
        if ((currentPage > 0) && (currentPage >= pageCount)) {
            currentPage = pageCount - 1;
        }

        addStateChange();
        this.currentPage = currentPage;
    }

    /**
     * Prevent users from accidentally using it.
     * 
     * @see org.apache.wicket.markup.html.list.ListView#setStartIndex(int)
     * @throws UnsupportedOperationException
     *             always
     */
    @Override
    public ListView<T> setStartIndex(int startIndex) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("You must not use setStartIndex() with PageableListView");
    }

    /**
     * Prevent users from accidentally using it.
     * 
     * @param size
     *            the view size
     * @return This
     * @throws UnsupportedOperationException
     *             always
     * @see org.apache.wicket.markup.html.list.ListView#setStartIndex(int)
     */
    @Override
    public ListView<T> setViewSize(int size) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("You must not use setViewSize() with PageableListView");
    }

}