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.user.client.ui; import com.google.gwt.dom.client.Document; import com.google.gwt.dom.client.Element; import com.google.gwt.dom.client.InputElement; import com.google.gwt.editor.client.IsEditor; import com.google.gwt.editor.client.LeafValueEditor; import com.google.gwt.editor.client.adapters.TakesValueEditor; import com.google.gwt.user.client.TakesValue; /** * A simple checkbox widget, with no label. * * <h3>CSS Style Rules</h3> * <ul class='css'> * <li>.gwt-SimpleCheckBox { }</li> * <li>.gwt-SimpleCheckBox-disabled { Applied when checkbox is disabled }</li> * </ul> */ public class SimpleCheckBox extends FocusWidget implements HasName, TakesValue<Boolean>, IsEditor<LeafValueEditor<Boolean>> { /** * Creates a SimpleCheckBox widget that wraps an existing <input * type='checkbox'> element. * * This element must already be attached to the document. If the element is * removed from the document, you must call * {@link RootPanel#detachNow(Widget)}. * * @param element the element to be wrapped */ public static SimpleCheckBox wrap(Element element) { // Assert that the element is attached. assert Document.get().getBody().isOrHasChild(element); SimpleCheckBox checkBox = new SimpleCheckBox(element); // Mark it attached and remember it for cleanup. checkBox.onAttach(); RootPanel.detachOnWindowClose(checkBox); return checkBox; } private LeafValueEditor<Boolean> editor; /** * Creates a new simple checkbox. */ public SimpleCheckBox() { this(Document.get().createCheckInputElement(), "gwt-SimpleCheckBox"); } /** * This constructor may be used by subclasses to explicitly use an existing * element. This element must be an <input> element whose type is either * 'checkbox'. * * @param element the element to be used */ protected SimpleCheckBox(Element element) { assert InputElement.as(element).getType().equalsIgnoreCase("checkbox"); setElement(element); } SimpleCheckBox(Element element, String styleName) { setElement(element); if (styleName != null) { setStyleName(styleName); } } public LeafValueEditor<Boolean> asEditor() { if (editor == null) { editor = TakesValueEditor.of(this); } return editor; } /** * Returns the value property of the input element that backs this widget. * This is the value that will be associated with the check box name and * submitted to the server if a {@link FormPanel} that holds it is submitted * and the box is checked. * <p> * Don't confuse this with {@link #getValue}, which returns true or false if * the widget is checked. */ public String getFormValue() { return getInputElement().getValue(); } public String getName() { return getInputElement().getName(); } /** * Determines whether this check box is currently checked. * <p> * Note that this <em>does not</em> return the value property of the checkbox * input element wrapped by this widget. For access to that property, see * {@link #getFormValue()} * * @return <code>true</code> if the check box is checked, false otherwise. * Will not return null */ public Boolean getValue() { String propName = isAttached() ? "checked" : "defaultChecked"; return getInputElement().getPropertyBoolean(propName); } /** * Determines whether this check box is currently checked. * * @return <code>true</code> if the check box is checked * @deprecated Use {@link #getValue} instead */ @Deprecated public boolean isChecked() { // Funny comparison b/c getValue could in theory return null return getValue() == true; } /** * Checks or unchecks this check box. * * @param checked <code>true</code> to check the check box * @deprecated Use {@link #setValue(Boolean)} instead */ @Deprecated public void setChecked(boolean checked) { setValue(checked); } @Override public void setEnabled(boolean enabled) { super.setEnabled(enabled); if (enabled) { removeStyleDependentName("disabled"); } else { addStyleDependentName("disabled"); } } /** * Set the value property on the input element that backs this widget. This is * the value that will be associated with the check box's name and submitted * to the server if a {@link FormPanel} that holds it is submitted and the box * is checked. * <p> * Don't confuse this with {@link #setValue}, which actually checks and * unchecks the box. * * @param value */ public void setFormValue(String value) { getInputElement().setAttribute("value", value); } public void setName(String name) { getInputElement().setName(name); } /** * Checks or unchecks the check box. * <p> * Note that this <em>does not</em> set the value property of the checkbox * input element wrapped by this widget. For access to that property, see * {@link #setFormValue(String)} * * @param value true to check, false to uncheck; null value implies false */ public void setValue(Boolean value) { if (value == null) { value = Boolean.FALSE; } getInputElement().setChecked(value); getInputElement().setDefaultChecked(value); } /** * This method is called when a widget is detached from the browser's * document. Overridden because of IE bug that throws away checked state. */ @Override protected void onUnload() { setValue(getValue()); } private InputElement getInputElement() { return InputElement.as(getElement()); } }