Java tutorial
/* * Copyright (c) 1996, 2003, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.beans; /** * A PropertyEditor class provides support for GUIs that want to * allow users to edit a property value of a given type. * <p> * PropertyEditor supports a variety of different kinds of ways of * displaying and updating property values. Most PropertyEditors will * only need to support a subset of the different options available in * this API. * <P> * Simple PropertyEditors may only support the getAsText and setAsText * methods and need not support (say) paintValue or getCustomEditor. More * complex types may be unable to support getAsText and setAsText but will * instead support paintValue and getCustomEditor. * <p> * Every propertyEditor must support one or more of the three simple * display styles. Thus it can either (1) support isPaintable or (2) * both return a non-null String[] from getTags() and return a non-null * value from getAsText or (3) simply return a non-null String from * getAsText(). * <p> * Every property editor must support a call on setValue when the argument * object is of the type for which this is the corresponding propertyEditor. * In addition, each property editor must either support a custom editor, * or support setAsText. * <p> * Each PropertyEditor should have a null constructor. * * @since 1.1 */ public interface PropertyEditor { /** * Set (or change) the object that is to be edited. Primitive types such * as "int" must be wrapped as the corresponding object type such as * "java.lang.Integer". * * @param value The new target object to be edited. Note that this * object should not be modified by the PropertyEditor, rather * the PropertyEditor should create a new object to hold any * modified value. */ void setValue(Object value); /** * Gets the property value. * * @return The value of the property. Primitive types such as "int" will * be wrapped as the corresponding object type such as "java.lang.Integer". */ Object getValue(); //---------------------------------------------------------------------- /** * Determines whether this property editor is paintable. * * @return True if the class will honor the paintValue method. */ boolean isPaintable(); /** * Paint a representation of the value into a given area of screen * real estate. Note that the propertyEditor is responsible for doing * its own clipping so that it fits into the given rectangle. * <p> * If the PropertyEditor doesn't honor paint requests (see isPaintable) * this method should be a silent noop. * <p> * The given Graphics object will have the default font, color, etc of * the parent container. The PropertyEditor may change graphics attributes * such as font and color and doesn't need to restore the old values. * * @param gfx Graphics object to paint into. * @param box Rectangle within graphics object into which we should paint. */ void paintValue(java.awt.Graphics gfx, java.awt.Rectangle box); //---------------------------------------------------------------------- /** * Returns a fragment of Java code that can be used to set a property * to match the editors current state. This method is intended * for use when generating Java code to reflect changes made through the * property editor. * <p> * The code fragment should be context free and must be a legal Java * expression as specified by the JLS. * <p> * Specifically, if the expression represents a computation then all * classes and static members should be fully qualified. This rule * applies to constructors, static methods and non primitive arguments. * <p> * Caution should be used when evaluating the expression as it may throw * exceptions. In particular, code generators must ensure that generated * code will compile in the presence of an expression that can throw * checked exceptions. * <p> * Example results are: * <ul> * <li>Primitive expresssion: {@code 2} * <li>Class constructor: {@code new java.awt.Color(127,127,34)} * <li>Static field: {@code java.awt.Color.orange} * <li>Static method: {@code javax.swing.Box.createRigidArea(new * java.awt.Dimension(0, 5))} * </ul> * * @return a fragment of Java code representing an initializer for the * current value. It should not contain a semi-colon * ('{@code ;}') to end the expression. */ String getJavaInitializationString(); //---------------------------------------------------------------------- /** * Gets the property value as text. * * @return The property value as a human editable string. * <p> Returns null if the value can't be expressed as an editable string. * <p> If a non-null value is returned, then the PropertyEditor should * be prepared to parse that string back in setAsText(). */ String getAsText(); /** * Set the property value by parsing a given String. May raise * java.lang.IllegalArgumentException if either the String is * badly formatted or if this kind of property can't be expressed * as text. * @param text The string to be parsed. */ void setAsText(String text) throws java.lang.IllegalArgumentException; //---------------------------------------------------------------------- /** * If the property value must be one of a set of known tagged values, * then this method should return an array of the tags. This can * be used to represent (for example) enum values. If a PropertyEditor * supports tags, then it should support the use of setAsText with * a tag value as a way of setting the value and the use of getAsText * to identify the current value. * * @return The tag values for this property. May be null if this * property cannot be represented as a tagged value. * */ String[] getTags(); //---------------------------------------------------------------------- /** * A PropertyEditor may choose to make available a full custom Component * that edits its property value. It is the responsibility of the * PropertyEditor to hook itself up to its editor Component itself and * to report property value changes by firing a PropertyChange event. * <P> * The higher-level code that calls getCustomEditor may either embed * the Component in some larger property sheet, or it may put it in * its own individual dialog, or ... * * @return A java.awt.Component that will allow a human to directly * edit the current property value. May be null if this is * not supported. */ java.awt.Component getCustomEditor(); /** * Determines whether this property editor supports a custom editor. * * @return True if the propertyEditor can provide a custom editor. */ boolean supportsCustomEditor(); //---------------------------------------------------------------------- /** * Adds a listener for the value change. * When the property editor changes its value * it should fire a {@link PropertyChangeEvent} * on all registered {@link PropertyChangeListener}s, * specifying the {@code null} value for the property name * and itself as the source. * * @param listener the {@link PropertyChangeListener} to add */ void addPropertyChangeListener(PropertyChangeListener listener); /** * Removes a listener for the value change. * * @param listener the {@link PropertyChangeListener} to remove */ void removePropertyChangeListener(PropertyChangeListener listener); }