1 /*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package javafx.scene.control;
26
27 import java.lang.ref.WeakReference;
28 import java.util.ArrayList;
29 import java.util.Arrays;
30 import java.util.List;
31 import java.util.Optional;
32
33 import com.sun.javafx.scene.control.skin.resources.ControlResources;
34 import javafx.beans.InvalidationListener;
35 import javafx.beans.NamedArg;
36 import javafx.beans.property.ObjectProperty;
37 import javafx.beans.property.SimpleObjectProperty;
38 import javafx.collections.ListChangeListener;
39 import javafx.collections.ObservableList;
40
41 /**
42 * The Alert class subclasses the {@link Dialog} class, and provides support for a number
43 * of pre-built dialog types that can be easily shown to users to prompt for a
44 * response. Therefore, for many users, the Alert class is the most suited class
45 * for their needs (as opposed to using {@link Dialog} directly). Alternatively,
46 * users who want to prompt a user for text input or to make a choice from a list
47 * of options would be better served by using {@link TextInputDialog} and
48 * {@link ChoiceDialog}, respectively.
49 *
50 * <p>When creating an Alert instance, users must pass in an {@link AlertType}
51 * enumeration value. It is by passing in this value that the Alert instance will
52 * configure itself appropriately (by setting default values for many of the
53 * {@link Dialog} properties, including {@link #titleProperty() title},
54 * {@link #headerTextProperty() header}, and {@link #graphicProperty() graphic},
55 * as well as the default {@link #getButtonTypes() buttons} that are expected in
56 * a dialog of the given type.
57 *
58 * <p>To instantiate (but not yet show) an Alert, simply use code such as the following:
59 * {@code Alert alert = new Alert(AlertType.CONFIRMATION, "Are you sure you want to format your system?");}
60 *
61 * <p>Once an Alert is instantiated, we must show it. More often than not, alerts
62 * (and dialogs in general) are shown in a modal and blocking fashion. 'Modal'
63 * means that the dialog prevents user interaction with the owning application
64 * whilst it is showing, and 'blocking' means that code execution stops at the
65 * point in which the dialog is shown. This means that you can show a dialog,
66 * await the user response, and then continue running the code that directly
67 * follows the show call, giving developers the ability to immediately deal with
68 * the user input from the dialog (if relevant).
69 *
70 * <p>JavaFX dialogs are modal by default (you can change this via the
71 * {@link #initModality(javafx.stage.Modality)} API). To specify whether you want
72 * blocking or non-blocking dialogs, developers simply choose to call
73 * {@link #showAndWait()} or {@link #show()} (respectively). By default most
74 * developers should choose to use {@link #showAndWait()}, given the ease of
75 * coding in these situations. Shown below is three code snippets, showing three
76 * equally valid ways of showing the Alert dialog that was specified above:
77 *
78 * <p><strong>Option 1: The 'traditional' approach</strong>
79 * <pre>{@code Optional<ButtonType> result = alert.showAndWait();
80 * if (result.isPresent() && result.get() == ButtonType.OK) {
81 * formatSystem();
82 * }}</pre>
83 *
84 * <p><strong>Option 2: The traditional + Optional approach</strong>
85 * <pre>{@code alert.showAndWait().ifPresent(response -> {
86 * if (response == ButtonType.OK) {
87 * formatSystem();
88 * }
89 * });}</pre>
90 *
91 * <p><strong>Option 3: The fully lambda approach</strong>
92 * <pre>{@code alert.showAndWait()
93 * .filter(response -> response == ButtonType.OK)
94 * .ifPresent(response -> formatSystem());
95 * }</pre>
96 *
97 * <p>There is no better or worse option of the three listed above, so developers
98 * are encouraged to work to their own style preferences. The purpose of showing
99 * the above is to help introduce developers to the {@link Optional} API, which
100 * is new in Java 8 and may be foreign to many developers.
101 *
102 * @see Dialog
103 * @see AlertType
104 * @see TextInputDialog
105 * @see ChoiceDialog
106 * @since JavaFX 8u40
107 */
108 public class Alert extends Dialog<ButtonType> {
109
110 /**************************************************************************
111 *
112 * Static enums
113 *
114 **************************************************************************/
115
116 /**
117 * An enumeration containing the available, pre-built alert types that
118 * the {@link Alert} class can use to pre-populate various properties.
119 *
120 * @since JavaFX 8u40
121 */
122 public static enum AlertType {
123 /**
124 * The NONE alert type has the effect of not setting any default properties
125 * in the Alert.
126 */
127 NONE,
128
129 /**
130 * The INFORMATION alert type configures the Alert dialog to appear in a
131 * way that suggests the content of the dialog is informing the user of
132 * a piece of information. This includes an 'information' image, an
133 * appropriate title and header, and just an OK button for the user to
134 * click on to dismiss the dialog.
135 */
136 INFORMATION,
137
138 /**
139 * The WARNING alert type configures the Alert dialog to appear in a
140 * way that suggests the content of the dialog is warning the user about
141 * some fact or action. This includes a 'warning' image, an
142 * appropriate title and header, and just an OK button for the user to
143 * click on to dismiss the dialog.
144 */
145 WARNING,
146
147 /**
148 * The CONFIRMATION alert type configures the Alert dialog to appear in a
149 * way that suggests the content of the dialog is seeking confirmation from
150 * the user. This includes a 'confirmation' image, an
151 * appropriate title and header, and both OK and Cancel buttons for the
152 * user to click on to dismiss the dialog.
153 */
154 CONFIRMATION,
155
156 /**
157 * The ERROR alert type configures the Alert dialog to appear in a
158 * way that suggests that something has gone wrong. This includes an
159 * 'error' image, an appropriate title and header, and just an OK button
160 * for the user to click on to dismiss the dialog.
161 */
162 ERROR
163 }
164
165
166
167 /**************************************************************************
168 *
169 * Fields
170 *
171 **************************************************************************/
172
173 private WeakReference<DialogPane> dialogPaneRef;
174
175 private boolean installingDefaults = false;
176 private boolean hasCustomButtons = false;
177 private boolean hasCustomTitle = false;
178 private boolean hasCustomHeaderText = false;
179
180 private final InvalidationListener headerTextListener = o -> {
181 if (!installingDefaults) hasCustomHeaderText = true;
182 };
183
184 private final InvalidationListener titleListener = o -> {
185 if (!installingDefaults) hasCustomTitle = true;
186 };
187
188 private final ListChangeListener<ButtonType> buttonsListener = change -> {
189 if (!installingDefaults) hasCustomButtons = true;
190 };
191
192
193
194 /**************************************************************************
195 *
196 * Constructors
197 *
198 **************************************************************************/
199
200 /**
201 * Creates an alert with the given AlertType (refer to the {@link AlertType}
202 * documentation for clarification over which one is most appropriate).
203 *
204 * <p>By passing in an AlertType, default values for the
205 * {@link #titleProperty() title}, {@link #headerTextProperty() headerText},
206 * and {@link #graphicProperty() graphic} properties are set, as well as the
207 * relevant {@link #getButtonTypes() buttons} being installed. Once the Alert
208 * is instantiated, developers are able to modify the values of the alert as
209 * desired.
210 *
211 * <p>It is important to note that the one property that does not have a
212 * default value set, and which therefore the developer must set, is the
213 * {@link #contentTextProperty() content text} property (or alternatively,
214 * the developer may call {@code alert.getDialogPane().setContent(Node)} if
215 * they want a more complex alert). If the contentText (or content) properties
216 * are not set, there is no useful information presented to end users.
217 */
218 public Alert(@NamedArg("alertType") AlertType alertType) {
219 this(alertType, "");
220 }
221
222 /**
223 * Creates an alert with the given contentText, ButtonTypes, and AlertType
224 * (refer to the {@link AlertType} documentation for clarification over which
225 * one is most appropriate).
226 *
227 * <p>By passing in a variable number of ButtonType arguments, the developer
228 * is directly overriding the default buttons that will be displayed in the
229 * dialog, replacing the pre-defined buttons with whatever is specified in the
230 * varargs array.
231 *
232 * <p>By passing in an AlertType, default values for the
233 * {@link #titleProperty() title}, {@link #headerTextProperty() headerText},
234 * and {@link #graphicProperty() graphic} properties are set. Once the Alert
235 * is instantiated, developers are able to modify the values of the alert as
236 * desired.
237 */
238 public Alert(@NamedArg("alertType") AlertType alertType,
239 @NamedArg("contentText") String contentText,
240 @NamedArg("buttonTypes") ButtonType... buttons) {
241 super();
242
243 final DialogPane dialogPane = getDialogPane();
244 dialogPane.setContentText(contentText);
245 getDialogPane().getStyleClass().add("alert");
246
247 dialogPaneRef = new WeakReference<>(dialogPane);
248
249 hasCustomButtons = buttons != null && buttons.length > 0;
250 if (hasCustomButtons) {
251 for (ButtonType btnType : buttons) {
252 dialogPane.getButtonTypes().addAll(btnType);
253 }
254 }
255
256 setAlertType(alertType);
257
258 // listening to property changes on Dialog and DialogPane
259 dialogPaneProperty().addListener(o -> updateListeners());
260 titleProperty().addListener(titleListener);
261 updateListeners();
262 }
263
264
265
266 /**************************************************************************
267 *
268 * Properties
269 *
270 **************************************************************************/
271
272 /**
273 * When creating an Alert instance, users must pass in an {@link AlertType}
274 * enumeration value. It is by passing in this value that the Alert instance will
275 * configure itself appropriately (by setting default values for many of the
276 * {@link Dialog} properties, including {@link #titleProperty() title},
277 * {@link #headerTextProperty() header}, and {@link #graphicProperty() graphic},
278 * as well as the default {@link #getButtonTypes() buttons} that are expected in
279 * a dialog of the given type.
280 */
281 // --- alertType
282 private final ObjectProperty<AlertType> alertType = new SimpleObjectProperty<AlertType>(null) {
283 final String[] styleClasses = new String[] { "information", "warning", "error", "confirmation" };
284
285 protected void invalidated() {
286 String newTitle = "";
287 String newHeader = "";
288 // Node newGraphic = null;
289 String styleClass = "";
290 ButtonType[] newButtons = new ButtonType[] { ButtonType.OK };
291 switch (getAlertType()) {
292 case NONE: {
293 newButtons = new ButtonType[] { };
294 break;
295 }
296 case INFORMATION: {
297 newTitle = ControlResources.getString("Dialog.info.title");
298 newHeader = ControlResources.getString("Dialog.info.header");
299 styleClass = "information";
300 break;
301 }
302 case WARNING: {
303 newTitle = ControlResources.getString("Dialog.warning.title");
304 newHeader = ControlResources.getString("Dialog.warning.header");
305 styleClass = "warning";
306 break;
307 }
308 case ERROR: {
309 newTitle = ControlResources.getString("Dialog.error.title");
310 newHeader = ControlResources.getString("Dialog.error.header");
311 styleClass = "error";
312 break;
313 }
314 case CONFIRMATION: {
315 newTitle = ControlResources.getString("Dialog.confirm.title");
316 newHeader = ControlResources.getString("Dialog.confirm.header");
317 styleClass = "confirmation";
318 newButtons = new ButtonType[] { ButtonType.OK, ButtonType.CANCEL };
319 break;
320 }
321 }
322
323 installingDefaults = true;
324 if (!hasCustomTitle) setTitle(newTitle);
325 if (!hasCustomHeaderText) setHeaderText(newHeader);
326 if (!hasCustomButtons) getButtonTypes().setAll(newButtons);
327
328 // update the style class based on the alert type. We use this to
329 // specify the default graphic to use (i.e. via CSS).
330 DialogPane dialogPane = getDialogPane();
331 if (dialogPane != null) {
332 List<String> toRemove = new ArrayList<>(Arrays.asList(styleClasses));
333 toRemove.remove(styleClass);
334 dialogPane.getStyleClass().removeAll(toRemove);
335 if (! dialogPane.getStyleClass().contains(styleClass)) {
336 dialogPane.getStyleClass().add(styleClass);
337 }
338 }
339
340 installingDefaults = false;
341 }
342 };
343
344 public final AlertType getAlertType() {
345 return alertType.get();
346 }
347
348 public final void setAlertType(AlertType alertType) {
349 this.alertType.setValue(alertType);
350 }
351
352 public final ObjectProperty<AlertType> alertTypeProperty() {
353 return alertType;
354 }
355
356
357 /**
358 * Returns an {@link ObservableList} of all {@link ButtonType} instances that
359 * are currently set inside this Alert instance. A ButtonType may either be one
360 * of the pre-defined types (e.g. {@link ButtonType#OK}), or it may be a
361 * custom type (created via the {@link ButtonType#ButtonType(String)} or
362 * {@link ButtonType#ButtonType(String, javafx.scene.control.ButtonBar.ButtonData)}
363 * constructors.
364 *
365 * <p>Readers should refer to the {@link ButtonType} class documentation for more details,
366 * but at a high level, each ButtonType instance is converted to
367 * a Node (although most commonly a {@link Button}) via the (overridable)
368 * {@link DialogPane#createButton(ButtonType)} method on {@link DialogPane}.
369 */
370 // --- buttonTypes
371 public final ObservableList<ButtonType> getButtonTypes() {
372 return getDialogPane().getButtonTypes();
373 }
374
375
376
377 /**************************************************************************
378 *
379 * Private Implementation
380 *
381 **************************************************************************/
382
383 private void updateListeners() {
384 DialogPane oldPane = dialogPaneRef.get();
385
386 if (oldPane != null) {
387 oldPane.headerTextProperty().removeListener(headerTextListener);
388 oldPane.getButtonTypes().removeListener(buttonsListener);
389 }
390
391 // listen to changes to properties that would be changed by alertType being
392 // changed, so that we only change values that are still at their default
393 // value (i.e. the user hasn't changed them, so we are free to set them
394 // to a new default value when the alertType changes).
395
396 DialogPane newPane = getDialogPane();
397 if (newPane != null) {
398 newPane.headerTextProperty().addListener(headerTextListener);
399 newPane.getButtonTypes().addListener(buttonsListener);
400 }
401
402 dialogPaneRef = new WeakReference<DialogPane>(newPane);
403 }
404 }