Java tutorial
/******************************************************************************* * * Copyright (c) 2012 Google, Inc. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * Google, Inc. - initial API and implementation *******************************************************************************/ package com.swtdesigner; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import org.eclipse.jface.preference.FieldEditor; import org.eclipse.jface.preference.PreferencePage; import org.eclipse.jface.resource.ImageDescriptor; import org.eclipse.jface.util.IPropertyChangeListener; import org.eclipse.jface.util.PropertyChangeEvent; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Control; /** * A special abstract preference page to host field editors and eny other controls * with flexible layout. * <p> * Subclasses must implement the <code>createPageContents</code>. * </p> * * This class may be freely distributed as part of any application or plugin. * @version $Revision: 1.1 $ * @author scheglov_ke */ public abstract class FieldLayoutPreferencePage extends PreferencePage implements IPropertyChangeListener { /** * The field editors. */ private List fields = new ArrayList(); /** * The first invalid field editor, or <code>null</code> * if all field editors are valid. */ private FieldEditor invalidFieldEditor = null; /** * Creates a new field editor preference page with an empty title, and no image. */ protected FieldLayoutPreferencePage() { } /** * Creates a new field editor preference page with the given title, but no image. * * @param title the title of this preference page */ protected FieldLayoutPreferencePage(String title) { super(title); } /** * Creates a new field editor preference page with the given image, and style. * * @param title the title of this preference page * @param image the image for this preference page, or <code>null</code> if none */ protected FieldLayoutPreferencePage(String title, ImageDescriptor image) { super(title, image); } /** * Adds the given field editor to this page. * * @param editor the field editor */ protected void addField(FieldEditor editor) { if (fields == null) fields = new ArrayList(); fields.add(editor); } /** * Recomputes the page's error state by calling <code>isValid</code> for * every field editor. */ protected void checkState() { boolean valid = true; invalidFieldEditor = null; // The state can only be set to true if all // field editors contain a valid value. So we must check them all if (fields != null) { int size = fields.size(); for (int i = 0; i < size; i++) { FieldEditor editor = (FieldEditor) fields.get(i); valid = valid && editor.isValid(); if (!valid) { invalidFieldEditor = editor; break; } } } setValid(valid); } /* (non-Javadoc) * Method declared on PreferencePage. */ protected Control createContents(Composite parent) { Control contens = createPageContents(parent); initialize(); checkState(); return contens; } /** * Creates and returns the SWT control for the customized body * of this preference page under the given parent composite. * <p> * This framework method must be implemented by concrete subclasses. Any * subclass returning a <code>Composite</code> object whose <code>Layout</code> * has default margins (for example, a <code>GridLayout</code>) are expected to * set the margins of this <code>Layout</code> to 0 pixels. * </p> * * @param parent the parent composite * @return the new control */ protected abstract Control createPageContents(Composite parent); /** * The field editor preference page implementation of an <code>IDialogPage</code> * method disposes of this page's controls and images. * Subclasses may override to release their own allocated SWT * resources, but must call <code>super.dispose</code>. */ public void dispose() { super.dispose(); if (fields != null) { Iterator e = fields.iterator(); while (e.hasNext()) { FieldEditor pe = (FieldEditor) e.next(); /* $codepro.preprocessor.if version >= 3.1 $ */ pe.setPage(null); /* $codepro.preprocessor.elseif version < 3.0 $ pe.setPreferencePage(null); $codepro.preprocessor.endif $ */ pe.setPropertyChangeListener(null); pe.setPreferenceStore(null); } } } /** * Initializes all field editors. */ protected void initialize() { if (fields != null) { Iterator e = fields.iterator(); while (e.hasNext()) { FieldEditor pe = (FieldEditor) e.next(); /* $codepro.preprocessor.if version >= 3.1 $ */ pe.setPage(null); /* $codepro.preprocessor.elseif version < 3.0 $ pe.setPreferencePage(null); $codepro.preprocessor.endif $ */ pe.setPropertyChangeListener(this); pe.setPreferenceStore(getPreferenceStore()); pe.load(); } } } /** * The field editor preference page implementation of a <code>PreferencePage</code> * method loads all the field editors with their default values. */ protected void performDefaults() { if (fields != null) { Iterator e = fields.iterator(); while (e.hasNext()) { FieldEditor pe = (FieldEditor) e.next(); pe.loadDefault(); } } // Force a recalculation of my error state. checkState(); super.performDefaults(); } /** * The field editor preference page implementation of this * <code>PreferencePage</code> method saves all field editors by * calling <code>FieldEditor.store</code>. Note that this method * does not save the preference store itself; it just stores the * values back into the preference store. * * @see FieldEditor#store() */ public boolean performOk() { if (fields != null) { Iterator e = fields.iterator(); while (e.hasNext()) { FieldEditor pe = (FieldEditor) e.next(); pe.store(); } } return true; } /** * The field editor preference page implementation of this <code>IPreferencePage</code> * (and <code>IPropertyChangeListener</code>) method intercepts <code>IS_VALID</code> * events but passes other events on to its superclass. */ public void propertyChange(PropertyChangeEvent event) { if (event.getProperty().equals(FieldEditor.IS_VALID)) { boolean newValue = ((Boolean) event.getNewValue()).booleanValue(); // If the new value is true then we must check all field editors. // If it is false, then the page is invalid in any case. if (newValue) { checkState(); } else { invalidFieldEditor = (FieldEditor) event.getSource(); setValid(newValue); } } } /* (non-Javadoc) * Method declared on IDialog. */ public void setVisible(boolean visible) { super.setVisible(visible); if (visible && invalidFieldEditor != null) { invalidFieldEditor.setFocus(); } } }