Java tutorial
/* * Copyright 2008 Google Inc. * * Licensed 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 com.google.gwt.sample.showcase.client.content.lists; import com.google.gwt.core.client.GWT; import com.google.gwt.core.client.RunAsyncCallback; import com.google.gwt.event.logical.shared.OpenEvent; import com.google.gwt.event.logical.shared.OpenHandler; import com.google.gwt.i18n.client.Constants; import com.google.gwt.sample.showcase.client.ContentWidget; import com.google.gwt.sample.showcase.client.ShowcaseAnnotations.ShowcaseData; import com.google.gwt.sample.showcase.client.ShowcaseAnnotations.ShowcaseSource; import com.google.gwt.sample.showcase.client.ShowcaseAnnotations.ShowcaseStyle; import com.google.gwt.user.client.Random; import com.google.gwt.user.client.rpc.AsyncCallback; import com.google.gwt.user.client.ui.DecoratorPanel; import com.google.gwt.user.client.ui.Grid; import com.google.gwt.user.client.ui.HasVerticalAlignment; import com.google.gwt.user.client.ui.ScrollPanel; import com.google.gwt.user.client.ui.Tree; import com.google.gwt.user.client.ui.TreeItem; import com.google.gwt.user.client.ui.Widget; /** * Example file. */ @ShowcaseStyle(".gwt-Tree") public class CwTree extends ContentWidget { /** * The constants used in this Content Widget. */ @ShowcaseSource public static interface CwConstants extends Constants { String[] cwTreeBeethovenWorkConcertos(); String[] cwTreeBeethovenWorkQuartets(); String[] cwTreeBeethovenWorkSonatas(); String[] cwTreeBeethovenWorkSymphonies(); String[] cwTreeBrahmsWorkConcertos(); String[] cwTreeBrahmsWorkQuartets(); String[] cwTreeBrahmsWorkSonatas(); String[] cwTreeBrahmsWorkSymphonies(); String[] cwTreeComposers(); String cwTreeConcertos(); String cwTreeDescription(); String cwTreeDynamicLabel(); String cwTreeItem(); String[] cwTreeMozartWorkConcertos(); String cwTreeName(); String cwTreeQuartets(); String cwTreeSonatas(); String cwTreeStaticLabel(); String cwTreeSymphonies(); } /** * An instance of the constants. */ @ShowcaseData private final CwConstants constants; /** * Constructor. * * @param constants the constants */ public CwTree(CwConstants constants) { super(constants.cwTreeName(), constants.cwTreeDescription(), true); this.constants = constants; } /** * Initialize this example. */ @ShowcaseSource @Override public Widget onInitialize() { // Create a static tree and a container to hold it Tree staticTree = createStaticTree(); staticTree.setAnimationEnabled(true); staticTree.ensureDebugId("cwTree-staticTree"); ScrollPanel staticTreeWrapper = new ScrollPanel(staticTree); staticTreeWrapper.ensureDebugId("cwTree-staticTree-Wrapper"); staticTreeWrapper.setSize("300px", "300px"); // Wrap the static tree in a DecoratorPanel DecoratorPanel staticDecorator = new DecoratorPanel(); staticDecorator.setWidget(staticTreeWrapper); // Create a dynamically generated tree and a container to hold it final Tree dynamicTree = createDynamicTree(); dynamicTree.ensureDebugId("cwTree-dynamicTree"); ScrollPanel dynamicTreeWrapper = new ScrollPanel(dynamicTree); dynamicTreeWrapper.ensureDebugId("cwTree-dynamicTree-Wrapper"); dynamicTreeWrapper.setSize("300px", "300px"); // Wrap the dynamic tree in a DecoratorPanel DecoratorPanel dynamicDecorator = new DecoratorPanel(); dynamicDecorator.setWidget(dynamicTreeWrapper); // Combine trees onto the page Grid grid = new Grid(2, 3); grid.setCellPadding(2); grid.getRowFormatter().setVerticalAlign(1, HasVerticalAlignment.ALIGN_TOP); grid.setHTML(0, 0, constants.cwTreeStaticLabel()); grid.setHTML(0, 1, " "); grid.setHTML(0, 2, constants.cwTreeDynamicLabel()); grid.setWidget(1, 0, staticDecorator); grid.setHTML(1, 1, " "); grid.setWidget(1, 2, dynamicDecorator); // Wrap the trees in DecoratorPanels return grid; } @Override protected void asyncOnInitialize(final AsyncCallback<Widget> callback) { GWT.runAsync(CwTree.class, new RunAsyncCallback() { public void onFailure(Throwable caught) { callback.onFailure(caught); } public void onSuccess() { callback.onSuccess(onInitialize()); } }); } /** * Add a new section of music created by a specific composer. * * @param parent the parent {@link TreeItem} where the section will be added * @param label the label of the new section of music * @param composerWorks an array of works created by the composer */ @ShowcaseSource private void addMusicSection(TreeItem parent, String label, String[] composerWorks) { TreeItem section = parent.addItem(label); for (String work : composerWorks) { section.addItem(work); } } /** * Create a dynamic tree that will add a random number of children to each * node as it is clicked. * * @return the new tree */ @ShowcaseSource private Tree createDynamicTree() { // Create a new tree Tree dynamicTree = new Tree(); // Add some default tree items for (int i = 0; i < 5; i++) { TreeItem item = dynamicTree.addItem(constants.cwTreeItem() + " " + i); // Temporarily add an item so we can expand this node item.addItem(""); } // Add a handler that automatically generates some children dynamicTree.addOpenHandler(new OpenHandler<TreeItem>() { public void onOpen(OpenEvent<TreeItem> event) { TreeItem item = event.getTarget(); if (item.getChildCount() == 1) { // Close the item immediately item.setState(false, false); // Add a random number of children to the item String itemText = item.getText(); int numChildren = Random.nextInt(5) + 2; for (int i = 0; i < numChildren; i++) { TreeItem child = item.addItem(itemText + "." + i); child.addItem(""); } // Remove the temporary item when we finish loading item.getChild(0).remove(); // Reopen the item item.setState(true, false); } } }); // Return the tree return dynamicTree; } /** * Create a static tree with some data in it. * * @return the new tree */ @ShowcaseSource private Tree createStaticTree() { // Create the tree String[] composers = constants.cwTreeComposers(); String concertosLabel = constants.cwTreeConcertos(); String quartetsLabel = constants.cwTreeQuartets(); String sonatasLabel = constants.cwTreeSonatas(); String symphoniesLabel = constants.cwTreeSymphonies(); Tree staticTree = new Tree(); // Add some of Beethoven's music TreeItem beethovenItem = staticTree.addItem(composers[0]); addMusicSection(beethovenItem, concertosLabel, constants.cwTreeBeethovenWorkConcertos()); addMusicSection(beethovenItem, quartetsLabel, constants.cwTreeBeethovenWorkQuartets()); addMusicSection(beethovenItem, sonatasLabel, constants.cwTreeBeethovenWorkSonatas()); addMusicSection(beethovenItem, symphoniesLabel, constants.cwTreeBeethovenWorkSymphonies()); // Add some of Brahms's music TreeItem brahmsItem = staticTree.addItem(composers[1]); addMusicSection(brahmsItem, concertosLabel, constants.cwTreeBrahmsWorkConcertos()); addMusicSection(brahmsItem, quartetsLabel, constants.cwTreeBrahmsWorkQuartets()); addMusicSection(brahmsItem, sonatasLabel, constants.cwTreeBrahmsWorkSonatas()); addMusicSection(brahmsItem, symphoniesLabel, constants.cwTreeBrahmsWorkSymphonies()); // Add some of Mozart's music TreeItem mozartItem = staticTree.addItem(composers[2]); addMusicSection(mozartItem, concertosLabel, constants.cwTreeMozartWorkConcertos()); // Return the tree return staticTree; } }