basiccomboboxeditor.java

java jdk 1.4的源码

/*
 * @(#)BasicComboBoxEditor.java	1.25 03/01/23
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.swing.plaf.basic;

import javax.swing.*;
import javax.swing.border.Border;

import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

import java.awt.*;
import java.awt.event.*;

import java.lang.reflect.Method;

/**
 * The default editor for editable combo boxes. The editor is implemented as a JTextField.
 *
 * @version 1.25 01/23/03
 * @author Arnaud Weber
 * @author Mark Davidson
 */
public class BasicComboBoxEditor implements ComboBoxEditor,FocusListener {
    protected JTextField editor;
    private Object oldValue;

    public BasicComboBoxEditor() {
        editor = new BorderlessTextField("",9);
        editor.setBorder(null);
    }

    public Component getEditorComponent() {
        return editor;
    }

    /** 
     * Sets the item that should be edited. 
     *
     * @param anObject the displayed value of the editor
     */
    public void setItem(Object anObject) {
        if ( anObject != null )  {
            editor.setText(anObject.toString());
            
            oldValue = anObject;
        } else {
            editor.setText("");
        }
    }

    public Object getItem() {
        Object newValue = editor.getText();
        
        if (oldValue != null && !(oldValue instanceof String))  {
            // The original value is not a string. Should return the value in it's
            // original type.
            if (newValue.equals(oldValue.toString()))  {
                return oldValue;
            } else {
                // Must take the value from the editor and get the value and cast it to the new type.
                Class cls = oldValue.getClass();
                try {
                    Method method = cls.getMethod("valueOf", new Class[]{String.class});
                    newValue = method.invoke(oldValue, new Object[] { editor.getText()});
                } catch (Exception ex) {
                    // Fail silently and return the newValue (a String object)
                }
            }
        }
        return newValue;
    }

    public void selectAll() {
        editor.selectAll();
        editor.requestFocus();
    }

    // This used to do something but now it doesn't.  It couldn't be
    // removed because it would be an API change to do so.
    public void focusGained(FocusEvent e) {}
    
    // This used to do something but now it doesn't.  It couldn't be
    // removed because it would be an API change to do so.
    public void focusLost(FocusEvent e) {}

    public void addActionListener(ActionListener l) {
        editor.addActionListener(l);
    }

    public void removeActionListener(ActionListener l) {
        editor.removeActionListener(l);
    }

    static class BorderlessTextField extends JTextField {
        public BorderlessTextField(String value,int n) {
            super(value,n);
        }

        // workaround for 4530952
        public void setText(String s) {
            if (getText().equals(s)) {
                return;
            }
            super.setText(s);
        }

        public void setBorder(Border b) {}
    }
    
    /**
     * A subclass of BasicComboBoxEditor that implements UIResource.
     * BasicComboBoxEditor doesn't implement UIResource
     * directly so that applications can safely override the
     * cellRenderer property with BasicListCellRenderer subclasses.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases. The current serialization support is
     * appropriate for short term storage or RMI between applications running
     * the same version of Swing.  As of 1.4, support for long term storage
     * of all JavaBeans<sup><font size="-2">TM</font></sup>
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    public static class UIResource extends BasicComboBoxEditor
    implements javax.swing.plaf.UIResource {
    }
}