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
* If the value of
* If the value of
* Specifying "" as the directory is exactly equivalent to
* specifying
* Specifying "" as the file is exactly equivalent to specifying
* show method to display the dialog,
* it blocks the rest of the application until the user has
* chosen a file.
*
* @see Window#show
*
* @version 1.53, 12/19/03
* @author Sami Shaio
* @author Arthur van Hoff
* @since JDK1.0
*/
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.
*/
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.
*/
public static final int SAVE = 1;
/*
* There are two FileDialog modes: LOAD and
* SAVE.
* This integer will represent one or the other.
* If the mode is not specified it will default to 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 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 null.
*
* @serial
* @see getFile()
* @see setFile()
*/
String file;
/*
* 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 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();
}
}
/**
* 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).
*
* @param parent the owner of the dialog
* @since JDK1.1
*/
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).
*
* @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.
* 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.
*
* @param parent the owner of the dialog
* @param title the title of the dialog
* @param mode the mode of the dialog; either
* FileDialog.LOAD or 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).
*
* @param parent the owner of the dialog
* @exception java.lang.IllegalArgumentException if the parent's
* GraphicsConfiguration
* is not from a screen device;
* @exception java.lang.IllegalArgumentException if parent
* is null; this exception is always thrown when
* GraphicsEnvironment.isHeadless
* returns 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).
*
* @param parent the owner of the dialog
* @param title the title of the dialog; a null value
* will be accepted without causing a
* NullPointerException to be thrown
* @exception java.lang.IllegalArgumentException if the parent's
* GraphicsConfiguration
* is not from a screen device;
* @exception java.lang.IllegalArgumentException if parent
* is null; this exception is always thrown when
* GraphicsEnvironment.isHeadless
* returns 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.
* 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.
*
* @param parent the owner of the dialog
* @param title the title of the dialog; a null value
* will be accepted without causing a
* NullPointerException to be thrown
* @param mode the mode of the dialog; either
* FileDialog.LOAD or FileDialog.SAVE
* @exception java.lang.IllegalArgumentException if an illegal
* file dialog mode is supplied;
* @exception java.lang.IllegalArgumentException if the parent's
* GraphicsConfiguration
* is not from a screen device;
* @exception java.lang.IllegalArgumentException if parent
* is null; this exception is always thrown when
* GraphicsEnvironment.isHeadless
* returns 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);
}
/**
* Constructs a name for this component. Called by getName()
* when the name is null.
*/
String constructComponentName() {
synchronized (getClass()) {
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.
*/
public void addNotify() {
synchronized(getTreeLock()) {
if (parent != null && parent.getPeer() == null) {
parent.addNotify();
}
if (peer == null)
peer = getToolkit().createFileDialog(this);
super.addNotify();
}
}
/**
* 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
* FileDialog.LOAD or
* 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.
*
* @param mode the mode for this file dialog, either
* FileDialog.LOAD or
* 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 JDK1.1
*/
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.
*
* @return the (potentially null or invalid)
* directory of this 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.
* 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.
*
* @return the currently selected file of this file dialog window,
* or null if none is selected
* @see java.awt.FileDialog#setFile
*/
public String getFile() {
return file;
}
/**
* 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.
* null
* as the file.
*
* @param file the file being set
* @see java.awt.FileDialog#getFile
*/
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);
}
}
/**
* 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.
*
* @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.
*
* @param s the 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.
*
* @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;
}
}