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.
+ *
+ * @see Window#show
+ *
+ * @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.
+ *
+ * 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.
+ *
+ * @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.
+ *
+ * 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.
+ *
+ * @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 (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.
+ */
+ 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.
+ *
+ * Specifying "" as the directory is exactly equivalent to
+ * specifying 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.
+ *
+ * Specifying "" as the file is exactly equivalent to specifying
+ * 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;
+ }
+}