ComboBoxEditorAdapter.java

/*
 * Copyright (c) 2006, 2015, Oracle. All rights reserved.
 *
 * This software is the proprietary information of Oracle Corporation.
 * Use is subject to license terms.
 */
package org.eclipse.persistence.tools.workbench.uitools.swing;

import java.awt.Component;
import java.awt.event.ActionListener;

import javax.swing.ComboBoxEditor;

import org.eclipse.persistence.tools.workbench.utility.string.BidiStringConverter;
import org.eclipse.persistence.tools.workbench.utility.string.StringTools;

/**
 * This adapter helps to convert the selected value to a string representation
 * before the default combo's editor receives it. Then once the edited value
 * needs to be pushed to the model, then another conversion is performed.
 *
 * @version 11.0.0
 * @since 11.0.0
 * @author Pascal Filion
 */
@SuppressWarnings("nls")
public class ComboBoxEditorAdapter implements ComboBoxEditor
{
    /**
     * The converter used to convert the selected value to a string or from the
     * edited string to the selected value.
     */
    private final BidiStringConverter converter;

    /**
     * The combo's editor used to delegate the behavior.
     */
    private final ComboBoxEditor delegate;

    /**
     * This defines what is the replacement of a <code>null</code> value since a
     * non-<code>null</code> value is required for proper selection in a combo
     * popup.
     */
    private final Object nullValue;

    /**
     * Creates a new <code>ComboBoxEditorAdapter</code>. No value is used to
     * represent the <code>null</code> value.
     *
     * @param delegate The combo's editor used to delegate the behavior
     * @param converter The <code>BidiStringConverter</code> used to convert the
     * item from the generic type to a string or vice versa
     */
    public ComboBoxEditorAdapter(ComboBoxEditor delegate,
                                 BidiStringConverter converter)
    {
        this(delegate, converter, null);
    }

    /**
     * Creates a new <code>ComboBoxEditorAdapter</code>.
     *
     * @param delegate The combo's editor used to delegate the behavior
     * @param converter The <code>BidiStringConverter</code> used to convert the
     * item from the generic type to a string or vice versa
     */
    @SuppressWarnings("unchecked")
    public ComboBoxEditorAdapter(ComboBoxEditor delegate,
                                 BidiStringConverter converter,
                                 Object nullValue)
    {
        super();

        this.delegate = delegate;
        this.converter = (BidiStringConverter) converter;
        this.nullValue = nullValue;
    }

    /*
     * (non-Javadoc)
     */
    public void addActionListener(ActionListener listener)
    {
        delegate.addActionListener(listener);
    }

    /*
     * (non-Javadoc)
     */
    public Component getEditorComponent()
    {
        return delegate.getEditorComponent();
    }

    /*
     * (non-Javadoc)
     */
    public Object getItem()
    {
        String value = (String) delegate.getItem();

        // Make sure there are no leading or trailing spaces
        if (value != null)
        {
            value = value.trim();
        }

        // Empty string was set, convert "null" to the string representation
        // and update the delegate
        if (StringTools.stringIsEmpty(value))
        {
            value = null;
        }
        // null-value, convert it to null before converting it
        // to the object representation
        else if (value == nullValue())
        {
            value = null;
        }

        // Convert the string value to the underlying model's object
        Object objectValue = converter.convertToObject(value);

        // null can't be used, use an empty string otherwise
        // JComboBox will ignore it
        if (objectValue == null)
        {
            objectValue = "";
        }

        return objectValue;
    }

    /**
     * Returns the value that represents the <code>null</code> item.
     *
     * @return The <code>null</code>-value
     */
    protected Object nullValue()
    {
        return nullValue;
    }

    /*
     * (non-Javadoc)
     */
    public void removeActionListener(ActionListener listener)
    {
        delegate.removeActionListener(listener);
    }

    /*
     * (non-Javadoc)
     */
    public void selectAll()
    {
        delegate.selectAll();
    }

    /*
     * (non-Javadoc)
     */
    public void setItem(Object value)
    {
        // Convert the null-value to null
        if (value == nullValue())
        {
            value = null;
        }

        // Convert the object to its string representation
        value = converter.convertToString(value);

        // Pass the value to the delegate
        delegate.setItem(value);
    }
}