JDK8/Java8源码在线阅读

/*
 * Copyright (c) 1997, 2013, 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 javax.swing.plaf.basic;

import javax.swing.ComboBoxEditor;
import javax.swing.JTextField;
import javax.swing.border.Border;
import java.awt.Component;
import java.awt.event.*;

import java.lang.reflect.Method;

import sun.reflect.misc.MethodUtil;

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

    public BasicComboBoxEditor() {
        editor = createEditorComponent();
    }

    public Component getEditorComponent() {
        return editor;
    }

    /**
     * Creates the internal editor component. Override this to provide
     * a custom implementation.
     *
     * @return a new editor component
     * @since 1.6
     */
    protected JTextField createEditorComponent() {
        JTextField editor = new BorderlessTextField("",9);
        editor.setBorder(null);
        return editor;
    }

    /**
     * Sets the item that should be edited.
     *
     * @param anObject the displayed value of the editor
     */
    public void setItem(Object anObject) {
        String text;

        if ( anObject != null )  {
            text = anObject.toString();
            if (text == null) {
                text = "";
            }
            oldValue = anObject;
        } else {
            text = "";
        }
        // workaround for 4530952
        if (! text.equals(editor.getText())) {
            editor.setText(text);
        }
    }

    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 = MethodUtil.getMethod(cls, "valueOf", new Class[]{String.class});
                    newValue = MethodUtil.invoke(method, 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) {
            if (!(b instanceof UIResource)) {
                super.setBorder(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>

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