java/10 : java.desktop/java/awt/FileDialog.java

FileDialog
https://openjdk.java.net/
GPLv2 + Classpath Exception
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package java.awt;

import java.awt.peer.FileDialogPeer;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.File;
import sun.awt.AWTAccessor;

The FileDialog class displays a dialog window from which the user can select a file.  Since it is a modal dialog, when the application calls its show method to display the dialog, it blocks the rest of the application until the user has chosen a file. 
Author:      Sami Shaio,      Arthur van Hoff
See Also: Window.show
Since:       1.0/**
 * The {@code FileDialog} class displays a dialog window
 * from which the user can select a file.
 * <p>
 * Since it is a modal dialog, when the application calls
 * its {@code show} method to display the dialog,
 * it blocks the rest of the application until the user has
 * chosen a file.
 *
 * @see Window#show
 *
 * @author      Sami Shaio
 * @author      Arthur van Hoff
 * @since       1.0
 */
public class FileDialog extends Dialog {

    This constant value indicates that the purpose of the file
dialog window is to locate a file from which to read.
/**
     * This constant value indicates that the purpose of the file
     * dialog window is to locate a file from which to read.
     */
    public static final int LOAD = 0;

    This constant value indicates that the purpose of the file
dialog window is to locate a file to which to write.
/**
     * This constant value indicates that the purpose of the file
     * dialog window is to locate a file to which to write.
     */
    public static final int SAVE = 1;

    /*
     * There are two {@code FileDialog} modes: {@code LOAD} and
     * {@code SAVE}.
     * This integer will represent one or the other.
     * If the mode is not specified it will default to {@code LOAD}.
     *
     * @serial
     * @see getMode()
     * @see setMode()
     * @see java.awt.FileDialog#LOAD
     * @see java.awt.FileDialog#SAVE
     */
    int mode;

    /*
     * The string specifying the directory to display
     * in the file dialog.  This variable may be {@code null}.
     *
     * @serial
     * @see getDirectory()
     * @see setDirectory()
     */
    String dir;

    /*
     * The string specifying the initial value of the
     * filename text field in the file dialog.
     * This variable may be {@code null}.
     *
     * @serial
     * @see getFile()
     * @see setFile()
     */
    String file;

    Contains the File instances for all the files that the user selects.
See Also: getFiles
@serial 
Since: 1.7/**
     * Contains the File instances for all the files that the user selects.
     *
     * @serial
     * @see #getFiles
     * @since 1.7
     */
    private File[] files;

    Represents whether the file dialog allows the multiple file selection.
See Also: setMultipleMode
isMultipleMode
@serial 
Since: 1.7/**
     * Represents whether the file dialog allows the multiple file selection.
     *
     * @serial
     * @see #setMultipleMode
     * @see #isMultipleMode
     * @since 1.7
     */
    private boolean multipleMode = false;

    /*
     * The filter used as the file dialog's filename filter.
     * The file dialog will only be displaying files whose
     * names are accepted by this filter.
     * This variable may be {@code null}.
     *
     * @serial
     * @see #getFilenameFilter()
     * @see #setFilenameFilter()
     * @see FileNameFilter
     */
    FilenameFilter filter;

    private static final String base = "filedlg";
    private static int nameCounter = 0;

    /*
     * JDK 1.1 serialVersionUID
     */
     private static final long serialVersionUID = 5035145889651310422L;


    static {
        /* ensure that the necessary native libraries are loaded */
        Toolkit.loadLibraries();
        if (!GraphicsEnvironment.isHeadless()) {
            initIDs();
        }
    }

    static {
        AWTAccessor.setFileDialogAccessor(
            new AWTAccessor.FileDialogAccessor() {
                public void setFiles(FileDialog fileDialog, File files[]) {
                    fileDialog.setFiles(files);
                }
                public void setFile(FileDialog fileDialog, String file) {
                    fileDialog.file = ("".equals(file)) ? null : file;
                }
                public void setDirectory(FileDialog fileDialog, String directory) {
                    fileDialog.dir = ("".equals(directory)) ? null : directory;
                }
                public boolean isMultipleMode(FileDialog fileDialog) {
                    synchronized (fileDialog.getObjectLock()) {
                        return fileDialog.multipleMode;
                    }
                }
            });
    }

    Initialize JNI field and method IDs for fields that may be
accessed from C.
/**
     * Initialize JNI field and method IDs for fields that may be
       accessed from C.
     */
    private static native void initIDs();

    Creates a file dialog for loading a file. The title of the file dialog is initially empty. This is a convenience method for FileDialog(parent, "", LOAD). 
Note: Some platforms may not support
showing the user-specified title in a file dialog.
In this situation, either no title will be displayed in the file dialog's
title bar or, on some systems, the file dialog's title bar will not be
displayed.
Params: parent – the owner of the dialog
Since: 1.1/**
     * Creates a file dialog for loading a file.  The title of the
     * file dialog is initially empty.  This is a convenience method for
     * {@code FileDialog(parent, "", LOAD)}.
     * <p>
     * <strong>Note:</strong> Some platforms may not support
     * showing the user-specified title in a file dialog.
     * In this situation, either no title will be displayed in the file dialog's
     * title bar or, on some systems, the file dialog's title bar will not be
     * displayed.
     *
     * @param parent the owner of the dialog
     * @since 1.1
     */
    public FileDialog(Frame parent) {
        this(parent, "", LOAD);
    }

    Creates a file dialog window with the specified title for loading a file. The files shown are those in the current directory. This is a convenience method for FileDialog(parent, title, LOAD). 
Note: Some platforms may not support
showing the user-specified title in a file dialog.
In this situation, either no title will be displayed in the file dialog's
title bar or, on some systems, the file dialog's title bar will not be
displayed.
Params: parent –   the owner of the dialog
title –    the title of the dialog/**
     * Creates a file dialog window with the specified title for loading
     * a file. The files shown are those in the current directory.
     * This is a convenience method for
     * {@code FileDialog(parent, title, LOAD)}.
     * <p>
     * <strong>Note:</strong> Some platforms may not support
     * showing the user-specified title in a file dialog.
     * In this situation, either no title will be displayed in the file dialog's
     * title bar or, on some systems, the file dialog's title bar will not be
     * displayed.
     *
     * @param     parent   the owner of the dialog
     * @param     title    the title of the dialog
     */
    public FileDialog(Frame parent, String title) {
        this(parent, title, LOAD);
    }

    Creates a file dialog window with the specified title for loading
or saving a file.
 If the value of mode is LOAD, then the file dialog is finding a file to read, and the files shown are those in the current directory. If the value of mode is SAVE, the file dialog is finding a place to write a file. 

Note: Some platforms may not support
showing the user-specified title in a file dialog.
In this situation, either no title will be displayed in the file dialog's
title bar or, on some systems, the file dialog's title bar will not be
displayed.
Params: parent –   the owner of the dialog
title –   the title of the dialog
mode –  the mode of the dialog; either FileDialog.LOAD or FileDialog.SAVE
Throws: IllegalArgumentException – if an illegal file
                dialog mode is supplied
See Also: LOAD
SAVE/**
     * Creates a file dialog window with the specified title for loading
     * or saving a file.
     * <p>
     * If the value of {@code mode} is {@code LOAD}, then the
     * file dialog is finding a file to read, and the files shown are those
     * in the current directory.   If the value of
     * {@code mode} is {@code SAVE}, the file dialog is finding
     * a place to write a file.
     * <p>
     * <strong>Note:</strong> Some platforms may not support
     * showing the user-specified title in a file dialog.
     * In this situation, either no title will be displayed in the file dialog's
     * title bar or, on some systems, the file dialog's title bar will not be
     * displayed.
     *
     * @param     parent   the owner of the dialog
     * @param     title   the title of the dialog
     * @param     mode   the mode of the dialog; either
     *            {@code FileDialog.LOAD} or {@code FileDialog.SAVE}
     * @exception  IllegalArgumentException if an illegal file
     *                 dialog mode is supplied
     * @see       java.awt.FileDialog#LOAD
     * @see       java.awt.FileDialog#SAVE
     */
    public FileDialog(Frame parent, String title, int mode) {
        super(parent, title, true);
        this.setMode(mode);
        setLayout(null);
    }

    Creates a file dialog for loading a file. The title of the file dialog is initially empty. This is a convenience method for FileDialog(parent, "", LOAD). 
Note: Some platforms may not support
showing the user-specified title in a file dialog.
In this situation, either no title will be displayed in the file dialog's
title bar or, on some systems, the file dialog's title bar will not be
displayed.
Params: parent –   the owner of the dialog
Throws: IllegalArgumentException – if the parent's GraphicsConfiguration is not from a screen device;
IllegalArgumentException – if parent is null; this exception is always thrown when GraphicsEnvironment.isHeadless returns true
See Also: GraphicsEnvironment.isHeadless
Since: 1.5/**
     * Creates a file dialog for loading a file.  The title of the
     * file dialog is initially empty.  This is a convenience method for
     * {@code FileDialog(parent, "", LOAD)}.
     * <p>
     * <strong>Note:</strong> Some platforms may not support
     * showing the user-specified title in a file dialog.
     * In this situation, either no title will be displayed in the file dialog's
     * title bar or, on some systems, the file dialog's title bar will not be
     * displayed.
     *
     * @param     parent   the owner of the dialog
     * @exception java.lang.IllegalArgumentException if the {@code parent}'s
     *            {@code GraphicsConfiguration}
     *            is not from a screen device;
     * @exception java.lang.IllegalArgumentException if {@code parent}
     *            is {@code null}; this exception is always thrown when
     *            {@code GraphicsEnvironment.isHeadless}
     *            returns {@code true}
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @since 1.5
     */
    public FileDialog(Dialog parent) {
        this(parent, "", LOAD);
    }

    Creates a file dialog window with the specified title for loading a file. The files shown are those in the current directory. This is a convenience method for FileDialog(parent, title, LOAD). 
Note: Some platforms may not support
showing the user-specified title in a file dialog.
In this situation, either no title will be displayed in the file dialog's
title bar or, on some systems, the file dialog's title bar will not be
displayed.
Params: parent –   the owner of the dialog
title –  the title of the dialog; a null value will be accepted without causing a NullPointerException to be thrown
Throws: IllegalArgumentException – if the parent's GraphicsConfiguration is not from a screen device;
IllegalArgumentException – if parent is null; this exception is always thrown when GraphicsEnvironment.isHeadless returns true
See Also: GraphicsEnvironment.isHeadless
Since:     1.5/**
     * Creates a file dialog window with the specified title for loading
     * a file. The files shown are those in the current directory.
     * This is a convenience method for
     * {@code FileDialog(parent, title, LOAD)}.
     * <p>
     * <strong>Note:</strong> Some platforms may not support
     * showing the user-specified title in a file dialog.
     * In this situation, either no title will be displayed in the file dialog's
     * title bar or, on some systems, the file dialog's title bar will not be
     * displayed.
     *
     * @param     parent   the owner of the dialog
     * @param     title    the title of the dialog; a {@code null} value
     *                     will be accepted without causing a
     *                     {@code NullPointerException} to be thrown
     * @exception java.lang.IllegalArgumentException if the {@code parent}'s
     *            {@code GraphicsConfiguration}
     *            is not from a screen device;
     * @exception java.lang.IllegalArgumentException if {@code parent}
     *            is {@code null}; this exception is always thrown when
     *            {@code GraphicsEnvironment.isHeadless}
     *            returns {@code true}
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @since     1.5
     */
    public FileDialog(Dialog parent, String title) {
        this(parent, title, LOAD);
    }

    Creates a file dialog window with the specified title for loading
or saving a file.
 If the value of mode is LOAD, then the file dialog is finding a file to read, and the files shown are those in the current directory. If the value of mode is SAVE, the file dialog is finding a place to write a file. 

Note: Some platforms may not support
showing the user-specified title in a file dialog.
In this situation, either no title will be displayed in the file dialog's
title bar or, on some systems, the file dialog's title bar will not be
displayed.
Params: parent –   the owner of the dialog
title –  the title of the dialog; a null value will be accepted without causing a NullPointerException to be thrown
mode –  the mode of the dialog; either FileDialog.LOAD or FileDialog.SAVE
Throws: IllegalArgumentException – if an illegal
           file dialog mode is supplied;
IllegalArgumentException – if the parent's GraphicsConfiguration is not from a screen device;
IllegalArgumentException – if parent is null; this exception is always thrown when GraphicsEnvironment.isHeadless returns true
See Also: GraphicsEnvironment.isHeadless
LOAD
SAVE
Since:     1.5/**
     * Creates a file dialog window with the specified title for loading
     * or saving a file.
     * <p>
     * If the value of {@code mode} is {@code LOAD}, then the
     * file dialog is finding a file to read, and the files shown are those
     * in the current directory.   If the value of
     * {@code mode} is {@code SAVE}, the file dialog is finding
     * a place to write a file.
     * <p>
     * <strong>Note:</strong> Some platforms may not support
     * showing the user-specified title in a file dialog.
     * In this situation, either no title will be displayed in the file dialog's
     * title bar or, on some systems, the file dialog's title bar will not be
     * displayed.
     *
     * @param     parent   the owner of the dialog
     * @param     title    the title of the dialog; a {@code null} value
     *                     will be accepted without causing a
     *                     {@code NullPointerException} to be thrown
     * @param     mode     the mode of the dialog; either
     *                     {@code FileDialog.LOAD} or {@code FileDialog.SAVE}
     * @exception java.lang.IllegalArgumentException if an illegal
     *            file dialog mode is supplied;
     * @exception java.lang.IllegalArgumentException if the {@code parent}'s
     *            {@code GraphicsConfiguration}
     *            is not from a screen device;
     * @exception java.lang.IllegalArgumentException if {@code parent}
     *            is {@code null}; this exception is always thrown when
     *            {@code GraphicsEnvironment.isHeadless}
     *            returns {@code true}
     * @see       java.awt.GraphicsEnvironment#isHeadless
     * @see       java.awt.FileDialog#LOAD
     * @see       java.awt.FileDialog#SAVE
     * @since     1.5
     */
    public FileDialog(Dialog parent, String title, int mode) {
        super(parent, title, true);
        this.setMode(mode);
        setLayout(null);
    }


    {@inheritDoc}

Note: Some platforms may not support
showing the user-specified title in a file dialog.
In this situation, either no title will be displayed in the file dialog's
title bar or, on some systems, the file dialog's title bar will not be
displayed.
/**
     * {@inheritDoc}
     * <p>
     * <strong>Note:</strong> Some platforms may not support
     * showing the user-specified title in a file dialog.
     * In this situation, either no title will be displayed in the file dialog's
     * title bar or, on some systems, the file dialog's title bar will not be
     * displayed.
     */
    @Override
    public void setTitle(String title) {
        super.setTitle(title);
    }


    Constructs a name for this component. Called by getName() when the name is null. /**
     * Constructs a name for this component. Called by {@code getName()}
     * when the name is {@code null}.
     */
    String constructComponentName() {
        synchronized (FileDialog.class) {
            return base + nameCounter++;
        }
    }

    Creates the file dialog's peer.  The peer allows us to change the look
of the file dialog without changing its functionality.
/**
     * Creates the file dialog's peer.  The peer allows us to change the look
     * of the file dialog without changing its functionality.
     */
    public void addNotify() {
        synchronized(getTreeLock()) {
            if (parent != null && parent.peer == null) {
                parent.addNotify();
            }
            if (peer == null)
                peer = getComponentFactory().createFileDialog(this);
            super.addNotify();
        }
    }

    Indicates whether this file dialog box is for loading from a file
or for saving to a file.
See Also: LOAD
SAVE
setMode
Returns:  the mode of this file dialog window, either FileDialog.LOAD or FileDialog.SAVE/**
     * Indicates whether this file dialog box is for loading from a file
     * or for saving to a file.
     *
     * @return   the mode of this file dialog window, either
     *               {@code FileDialog.LOAD} or
     *               {@code FileDialog.SAVE}
     * @see      java.awt.FileDialog#LOAD
     * @see      java.awt.FileDialog#SAVE
     * @see      java.awt.FileDialog#setMode
     */
    public int getMode() {
        return mode;
    }

    Sets the mode of the file dialog. If mode is not a legal value, an exception will be thrown and mode will not be set. 
Params: mode –  the mode for this file dialog, either FileDialog.LOAD or FileDialog.SAVE
Throws: IllegalArgumentException – if an illegal file
                dialog mode is supplied
See Also: LOAD
SAVE
getMode
Since:      1.1/**
     * Sets the mode of the file dialog.  If {@code mode} is not
     * a legal value, an exception will be thrown and {@code mode}
     * will not be set.
     *
     * @param      mode  the mode for this file dialog, either
     *                 {@code FileDialog.LOAD} or
     *                 {@code FileDialog.SAVE}
     * @see        java.awt.FileDialog#LOAD
     * @see        java.awt.FileDialog#SAVE
     * @see        java.awt.FileDialog#getMode
     * @exception  IllegalArgumentException if an illegal file
     *                 dialog mode is supplied
     * @since      1.1
     */
    public void setMode(int mode) {
        switch (mode) {
          case LOAD:
          case SAVE:
            this.mode = mode;
            break;
          default:
            throw new IllegalArgumentException("illegal file dialog mode");
        }
    }

    Gets the directory of this file dialog.
See Also: setDirectory
Returns:  the (potentially null or invalid) directory of this FileDialog/**
     * Gets the directory of this file dialog.
     *
     * @return  the (potentially {@code null} or invalid)
     *          directory of this {@code FileDialog}
     * @see       java.awt.FileDialog#setDirectory
     */
    public String getDirectory() {
        return dir;
    }

    Sets the directory of this file dialog window to be the specified directory. Specifying a null or an invalid directory implies an implementation-defined default. This default will not be realized, however, until the user has selected a file. Until this point, getDirectory() will return the value passed into this method.  Specifying "" as the directory is exactly equivalent to specifying null as the directory. 
Params: dir –   the specified directory
See Also: getDirectory/**
     * Sets the directory of this file dialog window to be the
     * specified directory. Specifying a {@code null} or an
     * invalid directory implies an implementation-defined default.
     * This default will not be realized, however, until the user
     * has selected a file. Until this point, {@code getDirectory()}
     * will return the value passed into this method.
     * <p>
     * Specifying "" as the directory is exactly equivalent to
     * specifying {@code null} as the directory.
     *
     * @param     dir   the specified directory
     * @see       java.awt.FileDialog#getDirectory
     */
    public void setDirectory(String dir) {
        this.dir = (dir != null && dir.equals("")) ? null : dir;
        FileDialogPeer peer = (FileDialogPeer)this.peer;
        if (peer != null) {
            peer.setDirectory(this.dir);
        }
    }

    Gets the selected file of this file dialog. If the user selected CANCEL, the returned file is null. 
See Also: setFile
Returns:  the currently selected file of this file dialog window, or null if none is selected/**
     * Gets the selected file of this file dialog.  If the user
     * selected {@code CANCEL}, the returned file is {@code null}.
     *
     * @return    the currently selected file of this file dialog window,
     *                or {@code null} if none is selected
     * @see       java.awt.FileDialog#setFile
     */
    public String getFile() {
        return file;
    }

    Returns files that the user selects.

If the user cancels the file dialog,
then the method returns an empty array.
See Also: setFile(String)
getFile
Returns:    files that the user selects or an empty array
           if the user cancels the file dialog.
Since: 1.7/**
     * Returns files that the user selects.
     * <p>
     * If the user cancels the file dialog,
     * then the method returns an empty array.
     *
     * @return    files that the user selects or an empty array
     *            if the user cancels the file dialog.
     * @see       #setFile(String)
     * @see       #getFile
     * @since 1.7
     */
    public File[] getFiles() {
        synchronized (getObjectLock()) {
            if (files != null) {
                return files.clone();
            } else {
                return new File[0];
            }
        }
    }

    Stores the names of all the files that the user selects.
Note that the method is private and it's intended to be used
by the peers through the AWTAccessor API.
Params: files –     the array that contains the short names of
                 all the files that the user selects.
See Also: getFiles
Since: 1.7/**
     * Stores the names of all the files that the user selects.
     *
     * Note that the method is private and it's intended to be used
     * by the peers through the AWTAccessor API.
     *
     * @param files     the array that contains the short names of
     *                  all the files that the user selects.
     *
     * @see #getFiles
     * @since 1.7
     */
    private void setFiles(File files[]) {
        synchronized (getObjectLock()) {
            this.files = files;
        }
    }

    Sets the selected file for this file dialog window to be the
specified file. This file becomes the default file if it is set
before the file dialog window is first shown.

When the dialog is shown, the specified file is selected. The kind of
selection depends on the file existence, the dialog type, and the native
platform. E.g., the file could be highlighted in the file list, or a
file name editbox could be populated with the file name.
 This method accepts either a full file path, or a file name with an extension if used together with the setDirectory method. 
 Specifying "" as the file is exactly equivalent to specifying null as the file. 
Params: file –   the file being set
See Also: getFile
getFiles/**
     * Sets the selected file for this file dialog window to be the
     * specified file. This file becomes the default file if it is set
     * before the file dialog window is first shown.
     * <p>
     * When the dialog is shown, the specified file is selected. The kind of
     * selection depends on the file existence, the dialog type, and the native
     * platform. E.g., the file could be highlighted in the file list, or a
     * file name editbox could be populated with the file name.
     * <p>
     * This method accepts either a full file path, or a file name with an
     * extension if used together with the {@code setDirectory} method.
     * <p>
     * Specifying "" as the file is exactly equivalent to specifying
     * {@code null} as the file.
     *
     * @param    file   the file being set
     * @see      #getFile
     * @see      #getFiles
     */
    public void setFile(String file) {
        this.file = (file != null && file.equals("")) ? null : file;
        FileDialogPeer peer = (FileDialogPeer)this.peer;
        if (peer != null) {
            peer.setFile(this.file);
        }
    }

    Enables or disables multiple file selection for the file dialog.
Params: enable –  if true, multiple file selection is enabled; false - disabled.
See Also: isMultipleMode
Since: 1.7/**
     * Enables or disables multiple file selection for the file dialog.
     *
     * @param enable    if {@code true}, multiple file selection is enabled;
     *                  {@code false} - disabled.
     * @see #isMultipleMode
     * @since 1.7
     */
    public void setMultipleMode(boolean enable) {
        synchronized (getObjectLock()) {
            this.multipleMode = enable;
        }
    }

    Returns whether the file dialog allows the multiple file selection.
See Also: setMultipleMode
Returns:  true if the file dialog allows the multiple file selection; false otherwise.
Since: 1.7/**
     * Returns whether the file dialog allows the multiple file selection.
     *
     * @return          {@code true} if the file dialog allows the multiple
     *                  file selection; {@code false} otherwise.
     * @see #setMultipleMode
     * @since 1.7
     */
    public boolean isMultipleMode() {
        synchronized (getObjectLock()) {
            return multipleMode;
        }
    }

    Determines this file dialog's filename filter. A filename filter
allows the user to specify which files appear in the file dialog
window.  Filename filters do not function in Sun's reference
implementation for Microsoft Windows.
See Also: FilenameFilter
setFilenameFilter
Returns:    this file dialog's filename filter/**
     * Determines this file dialog's filename filter. A filename filter
     * allows the user to specify which files appear in the file dialog
     * window.  Filename filters do not function in Sun's reference
     * implementation for Microsoft Windows.
     *
     * @return    this file dialog's filename filter
     * @see       java.io.FilenameFilter
     * @see       java.awt.FileDialog#setFilenameFilter
     */
    public FilenameFilter getFilenameFilter() {
        return filter;
    }

    Sets the filename filter for this file dialog window to the
specified filter.
Filename filters do not function in Sun's reference
implementation for Microsoft Windows.
Params: filter –   the specified filter
See Also: FilenameFilter
getFilenameFilter/**
     * Sets the filename filter for this file dialog window to the
     * specified filter.
     * Filename filters do not function in Sun's reference
     * implementation for Microsoft Windows.
     *
     * @param   filter   the specified filter
     * @see     java.io.FilenameFilter
     * @see     java.awt.FileDialog#getFilenameFilter
     */
    public synchronized void setFilenameFilter(FilenameFilter filter) {
        this.filter = filter;
        FileDialogPeer peer = (FileDialogPeer)this.peer;
        if (peer != null) {
            peer.setFilenameFilter(filter);
        }
    }

    Reads the ObjectInputStream and performs a backwards compatibility check by converting either a dir or a file equal to an empty string to null. 
Params: s – the ObjectInputStream to read/**
     * Reads the {@code ObjectInputStream} and performs
     * a backwards compatibility check by converting
     * either a {@code dir} or a {@code file}
     * equal to an empty string to {@code null}.
     *
     * @param s the {@code ObjectInputStream} to read
     */
    private void readObject(ObjectInputStream s)
        throws ClassNotFoundException, IOException
    {
        s.defaultReadObject();

        // 1.1 Compatibility: "" is not converted to null in 1.1
        if (dir != null && dir.equals("")) {
            dir = null;
        }
        if (file != null && file.equals("")) {
            file = null;
        }
    }

    Returns a string representing the state of this FileDialog window. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null. 
Returns:  the parameter string of this file dialog window/**
     * Returns a string representing the state of this {@code FileDialog}
     * window. This method is intended to be used only for debugging purposes,
     * and the content and format of the returned string may vary between
     * implementations. The returned string may be empty but may not be
     * {@code null}.
     *
     * @return  the parameter string of this file dialog window
     */
    protected String paramString() {
        String str = super.paramString();
        str += ",dir= " + dir;
        str += ",file= " + file;
        return str + ((mode == LOAD) ? ",load" : ",save");
    }

    boolean postsOldMouseEvents() {
        return false;
    }
}
Author:	Sami Shaio, Arthur van Hoff
See Also:	Window.show
Since:	1.0
Params:	parent – the owner of the dialog title – the title of the dialog mode – the mode of the dialog; either `FileDialog.LOAD` or `FileDialog.SAVE`
Throws:	IllegalArgumentException – if an illegal file dialog mode is supplied
See Also:	LOAD SAVE
Params:	parent – the owner of the dialog
Throws:	IllegalArgumentException – if the `parent`'s `GraphicsConfiguration` is not from a screen device; IllegalArgumentException – if `parent` is `null`; this exception is always thrown when `GraphicsEnvironment.isHeadless` returns `true`
See Also:	GraphicsEnvironment.isHeadless
Since:	1.5
See Also:	LOAD SAVE setMode
Returns:	the mode of this file dialog window, either `FileDialog.LOAD` or `FileDialog.SAVE`
Params:	mode – the mode for this file dialog, either `FileDialog.LOAD` or `FileDialog.SAVE`
Throws:	IllegalArgumentException – if an illegal file dialog mode is supplied
See Also:	LOAD SAVE getMode
Since:	1.1
See Also:	setDirectory
Returns:	the (potentially `null` or invalid) directory of this `FileDialog`
See Also:	setFile
Returns:	the currently selected file of this file dialog window, or `null` if none is selected
See Also:	setFile(String) getFile
Returns:	files that the user selects or an empty array if the user cancels the file dialog.
Since:	1.7
Params:	files – the array that contains the short names of all the files that the user selects.
See Also:	getFiles
Since:	1.7
Params:	enable – if `true`, multiple file selection is enabled; `false` - disabled.
See Also:	isMultipleMode
Since:	1.7
See Also:	setMultipleMode
Returns:	`true` if the file dialog allows the multiple file selection; `false` otherwise.
Since:	1.7
See Also:	FilenameFilter setFilenameFilter
Returns:	this file dialog's filename filter
Params:	filter – the specified filter
See Also:	FilenameFilter getFilenameFilter
/

java/ 10/ java.desktop/java/awt/FileDialog.java
