System File Chooser:

- introduced state storage
- added "New Folder" to macOS select folder dialog
- Demo: added "Select Folder (System)" menu item
- javadoc fixes

flatlaf-core/src/main/java/com/formdev/flatlaf/util/SystemFileChooser.java

@@ -60,6 +60,10 @@ import com.formdev.flatlaf.ui.FlatNativeWindowsLibrary;
  * {@code SystemFileChooser} requires FlatLaf native libraries (usually contained in flatlaf.jar).
  * If not available or disabled (via {@link FlatSystemProperties#USE_NATIVE_LIBRARY}
  * or {@link FlatSystemProperties#USE_SYSTEM_FILE_CHOOSER}), then {@code JFileChooser} is used.
+ * <p>
+ * To improve user experience, it is recommended to use a state storage
+ * (see {@link #setStateStore(StateStore)}), so that file dialogs open at previously
+ * visited folder.
  *
  * <h2>Limitations/incompatibilities compared to JFileChooser</h2>
  *
@@ -90,6 +94,11 @@ import com.formdev.flatlaf.ui.FlatNativeWindowsLibrary;
  *   <li><b>macOS</b>: By default, the user can not navigate into file packages (e.g. applications).
  *       If needed, this can be enabled by setting platform property
  *       {@link #MAC_TREATS_FILE_PACKAGES_AS_DIRECTORIES} to {@code true}.
+ *   <li>If no "current directory" is specified, then {@code JFileChooser} always opens
+ *       the users "Documents" folder (on Windows) or "Home" folder (on macOS and Linux).<br>
+ *       {@code SystemFileChooser} does the same when first shown, but then remembers
+ *       last visited folder (either in memory or in a {@link StateStore}) and
+ *       re-uses that folder when {@code SystemFileChooser} is shown again.
  * </ul>
  *
  * @author Karl Tauber
@@ -248,6 +257,25 @@ public class SystemFileChooser
 
 	private Map<String, Object> platformProperties;
 
+	private static final StateStore inMemoryStateStore = new StateStore() {
+		private final Map<String, String> state = new HashMap<>();
+
+		@Override
+		public String get( String key, String def ) {
+			return state.getOrDefault( key, def );
+		}
+
+		@Override
+		public void put( String key, String value ) {
+			if( value != null )
+				state.put( key, value );
+			else
+				state.remove( key );
+		}
+	};
+
+	private static StateStore stateStore;
+	private String stateStoreID;
 
 	/** @see JFileChooser#JFileChooser() */
 	public SystemFileChooser() {
@@ -384,18 +412,35 @@ public class SystemFileChooser
 
 	/** @see JFileChooser#getCurrentDirectory() */
 	public File getCurrentDirectory() {
+		if( currentDirectory == null ) {
+			// get current directory from state store
+			StateStore store = (stateStore != null) ? stateStore : inMemoryStateStore;
+			String path = store.get( buildStateKey( StateStore.KEY_CURRENT_DIRECTORY ), null );
+			if( path != null )
+				currentDirectory = getTraversableDirectory( FileSystemView.getFileSystemView().createFileObject( path ) );
+
+			// for compatibility with JFileChooser
+			if( currentDirectory == null )
+				currentDirectory = getTraversableDirectory( FileSystemView.getFileSystemView().getDefaultDirectory() );
+		}
+
 		return currentDirectory;
 	}
 
 	/** @see JFileChooser#setCurrentDirectory(File) */
 	public void setCurrentDirectory( File dir ) {
-		// for compatibility with JFileChooser
-		if( dir != null && !dir.exists() )
-			return;
-		if( dir == null )
-			dir = FileSystemView.getFileSystemView().getDefaultDirectory();
+		currentDirectory = getTraversableDirectory( dir );
+	}
 
-		currentDirectory = dir;
+	private File getTraversableDirectory( File dir ) {
+		if( dir == null )
+			return null;
+
+		// make sure to use existing (traversable) directory
+		FileSystemView fsv = FileSystemView.getFileSystemView();
+		while( dir != null && !fsv.isTraversable( dir ) )
+			dir = fsv.getParentDirectory( dir );
+		return dir;
 	}
 
 	/** @see JFileChooser#getSelectedFile() */
@@ -533,7 +578,7 @@ public class SystemFileChooser
 	 * Sets a callback that is invoked when user presses "OK" button (or double-clicks a file).
 	 * The file dialog is still open.
 	 * If the callback returns {@link #CANCEL_OPTION}, then the file dialog stays open.
-	 * If it returns {@link #APPROVE_OPTION} (or any other value other than {@link #CANCEL_OPTION}),
+	 * If it returns {@link #APPROVE_OPTION} (or any value other than {@link #CANCEL_OPTION}),
 	 * the file dialog is closed and the {@code show...Dialog()} methods return that value.
 	 * <p>
 	 * The callback has two parameters:
@@ -562,9 +607,9 @@ public class SystemFileChooser
 	 * }
 	 * }</pre>
 	 *
-	 * <b>WARNING:</b> Do not show a Swing dialog for the callback. This will not work!
+	 * <b>WARNING:</b> Do not show a Swing dialog from within the callback. This will not work!
 	 * <p>
-	 * Instead use {@link ApproveContext#showMessageDialog(int, String, String, int, String...)},
+	 * Instead, use {@link ApproveContext#showMessageDialog(int, String, String, int, String...)},
 	 * which shows a modal system message dialog as child of the file dialog.
 	 *
 	 * <pre>{@code
@@ -617,6 +662,43 @@ public class SystemFileChooser
 		return (value instanceof Integer) ? (Integer) value & ~optionsBlocked : 0;
 	}
 
+	/**
+	 * Returns state storage used to persist file chooser state (e.g. last used directory).
+	 * Or {@code null} if there is no state storage (the default).
+	 */
+	public static StateStore getStateStore() {
+		return stateStore;
+	}
+
+	/**
+	 * Sets state storage used to persist file chooser state (e.g. last used directory).
+	 */
+	public static void setStateStore( StateStore stateStore ) {
+		SystemFileChooser.stateStore = stateStore;
+	}
+
+	/**
+	 * Returns the ID used to prefix keys in state storage. Or {@code null} (the default).
+	 */
+	public String getStateStoreID() {
+		return stateStoreID;
+	}
+
+	/**
+	 * Sets the ID used to prefix keys in state storage. Or {@code null} (the default).
+	 * <p>
+	 * By specifying an ID, an application can have different persisted states
+	 * for different kinds of file dialogs within the application. E.g. Import/Export
+	 * file dialogs could use a different ID then Open/Save file dialogs.
+	 */
+	public void setStateStoreID( String stateStoreID ) {
+		this.stateStoreID = stateStoreID;
+	}
+
+	private String buildStateKey( String key ) {
+		return (stateStoreID != null) ? stateStoreID + '.' + key : key;
+	}
+
 	private int showDialogImpl( Component parent ) {
 		Window owner = (parent instanceof Window)
 			? (Window) parent
@@ -627,7 +709,16 @@ public class SystemFileChooser
 		approveResult = APPROVE_OPTION;
 		File[] files = getProvider().showDialog( owner, this );
 		setSelectedFiles( files );
-		return (files != null) ? approveResult : CANCEL_OPTION;
+		if( files == null )
+			return CANCEL_OPTION;
+
+		// remember current directory in state store
+		File currentDirectory = getCurrentDirectory();
+		StateStore store = (stateStore != null) ? stateStore : inMemoryStateStore;
+		store.put( buildStateKey( StateStore.KEY_CURRENT_DIRECTORY ),
+			(currentDirectory != null) ? currentDirectory.getAbsolutePath() : null );
+
+		return approveResult;
 	}
 
 	private FileChooserProvider getProvider() {
@@ -870,7 +961,7 @@ public class SystemFileChooser
 			if( (optionsClear & FlatNativeMacLibrary.FC_accessoryViewDisclosed) == 0 )
 				optionsSet |= FlatNativeMacLibrary.FC_accessoryViewDisclosed;
 			if( fc.isDirectorySelectionEnabled() ) {
-				optionsSet |= FlatNativeMacLibrary.FC_canChooseDirectories;
+				optionsSet |= FlatNativeMacLibrary.FC_canChooseDirectories | FlatNativeMacLibrary.FC_canCreateDirectories;
 				optionsClear |= FlatNativeMacLibrary.FC_canChooseFiles;
 				open = true;
 			}
@@ -1335,4 +1426,26 @@ public class SystemFileChooser
 		public abstract int showMessageDialog( int messageType, String primaryText,
 			String secondaryText, int defaultButton, String... buttons );
 	}
+
+	//---- class StateStore ---------------------------------------------------
+
+	/**
+	 * Simple state storage used to persist file chooser state (e.g. last used directory).
+	 *
+	 * @see SystemFileChooser#setStateStore(StateStore)
+	 * @see SystemFileChooser#setStateStoreID(String)
+	 */
+	public interface StateStore {
+		String KEY_CURRENT_DIRECTORY = "currentDirectory";
+
+		/**
+		 * Returns the value for the given key, or the default value if there is no value stored.
+		 */
+		String get( String key, String def );
+
+		/**
+		 * Stores the given key and value. If value is {@code null}, it is removed from the store.
+		 */
+		void put( String key, String value );
+	}
 }

flatlaf-demo/src/main/java/com/formdev/flatlaf/demo/DemoFrame.java

@@ -18,6 +18,7 @@ package com.formdev.flatlaf.demo;
 
 import java.awt.*;
 import java.awt.event.*;
+import java.io.File;
 import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
@@ -175,13 +176,19 @@ class DemoFrame
 
 	private void openSystemActionPerformed() {
 		SystemFileChooser chooser = new SystemFileChooser();
+		chooser.setMultiSelectionEnabled( true );
 		chooser.addChoosableFileFilter( new SystemFileChooser.FileNameExtensionFilter(
 			"Text Files", "txt", "md" ) );
 		chooser.addChoosableFileFilter( new SystemFileChooser.FileNameExtensionFilter(
 			"PDF Files", "pdf" ) );
 		chooser.addChoosableFileFilter( new SystemFileChooser.FileNameExtensionFilter(
 			"Archives", "zip", "tar", "jar", "7z" ) );
-		chooser.showOpenDialog( this );
+
+		if( chooser.showOpenDialog( this ) != SystemFileChooser.APPROVE_OPTION )
+			return;
+
+		File[] files = chooser.getSelectedFiles();
+		System.out.println( Arrays.toString( files ).replace( ",", "\n" ) );
 	}
 
 	private void saveAsSystemActionPerformed() {
@@ -190,7 +197,23 @@ class DemoFrame
 			"Text Files", "txt", "md" ) );
 		chooser.addChoosableFileFilter( new SystemFileChooser.FileNameExtensionFilter(
 			"Images", "png", "gif", "jpg" ) );
-		chooser.showSaveDialog( this );
+
+		if( chooser.showSaveDialog( this ) != SystemFileChooser.APPROVE_OPTION )
+			return;
+
+		File file = chooser.getSelectedFile();
+		System.out.println( file );
+	}
+
+	private void selectFolderSystemActionPerformed() {
+		SystemFileChooser chooser = new SystemFileChooser();
+		chooser.setFileSelectionMode( SystemFileChooser.DIRECTORIES_ONLY );
+
+		if( chooser.showOpenDialog( this ) != SystemFileChooser.APPROVE_OPTION )
+			return;
+
+		File directory  = chooser.getSelectedFile();
+		System.out.println( directory  );
 	}
 
 	private void exitActionPerformed() {
@@ -519,6 +542,7 @@ class DemoFrame
 		JMenuItem saveAsMenuItem = new JMenuItem();
 		JMenuItem openSystemMenuItem = new JMenuItem();
 		JMenuItem saveAsSystemMenuItem = new JMenuItem();
+		JMenuItem selectFolderSystemMenuItem = new JMenuItem();
 		JMenuItem closeMenuItem = new JMenuItem();
 		exitMenuItem = new JMenuItem();
 		JMenu editMenu = new JMenu();
@@ -630,6 +654,12 @@ class DemoFrame
 				saveAsSystemMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()|KeyEvent.SHIFT_DOWN_MASK));
 				saveAsSystemMenuItem.addActionListener(e -> saveAsSystemActionPerformed());
 				fileMenu.add(saveAsSystemMenuItem);
+
+				//---- selectFolderSystemMenuItem ----
+				selectFolderSystemMenuItem.setText("Select Folder (System)...");
+				selectFolderSystemMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()|KeyEvent.SHIFT_DOWN_MASK));
+				selectFolderSystemMenuItem.addActionListener(e -> selectFolderSystemActionPerformed());
+				fileMenu.add(selectFolderSystemMenuItem);
 				fileMenu.addSeparator();
 
 				//---- closeMenuItem ----

flatlaf-demo/src/main/java/com/formdev/flatlaf/demo/DemoFrame.jfd

@@ -197,6 +197,12 @@ new FormModel {
 						"accelerator": static javax.swing.KeyStroke getKeyStroke( 83, 4291, false )
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "saveAsSystemActionPerformed", false ) )
 					} )
+					add( new FormComponent( "javax.swing.JMenuItem" ) {
+						name: "selectFolderSystemMenuItem"
+						"text": "Select Folder (System)..."
+						"accelerator": static javax.swing.KeyStroke getKeyStroke( 70, 4291, false )
+						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "selectFolderSystemActionPerformed", false ) )
+					} )
 					add( new FormComponent( "javax.swing.JPopupMenu$Separator" ) {
 						name: "separator2"
 					} )

flatlaf-demo/src/main/java/com/formdev/flatlaf/demo/FlatLafDemo.java

@@ -17,6 +17,7 @@
 package com.formdev.flatlaf.demo;
 
 import java.awt.Dimension;
+import java.util.prefs.Preferences;
 import javax.swing.JDialog;
 import javax.swing.JFrame;
 import javax.swing.SwingUtilities;
@@ -27,6 +28,7 @@ import com.formdev.flatlaf.fonts.inter.FlatInterFont;
 import com.formdev.flatlaf.fonts.jetbrains_mono.FlatJetBrainsMonoFont;
 import com.formdev.flatlaf.fonts.roboto.FlatRobotoFont;
 import com.formdev.flatlaf.fonts.roboto_mono.FlatRobotoMonoFont;
+import com.formdev.flatlaf.util.SystemFileChooser;
 import com.formdev.flatlaf.util.SystemInfo;
 
 /**
@@ -73,6 +75,28 @@ public class FlatLafDemo
 		DemoPrefs.init( PREFS_ROOT_PATH );
 		DemoPrefs.initSystemScale();
 
+		// SystemFileChooser state storage
+		SystemFileChooser.setStateStore( new SystemFileChooser.StateStore() {
+			private static final String KEY_PREFIX = "fileChooser.";
+			private final Preferences state = Preferences.userRoot().node( PREFS_ROOT_PATH );
+
+			@Override
+			public String get( String key, String def ) {
+				String value = state.get( KEY_PREFIX + key, def );
+				System.out.println( "SystemFileChooser State GET " + key + " = " + value );
+				return value;
+			}
+
+			@Override
+			public void put( String key, String value ) {
+				System.out.println( "SystemFileChooser State PUT " + key + " = " + value );
+				if( value != null )
+					state.put( KEY_PREFIX + key, value );
+				else
+					state.remove( KEY_PREFIX + key );
+			}
+		} );
+
 		SwingUtilities.invokeLater( () -> {
 			// install fonts for lazy loading
 			FlatInterFont.installLazy();

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatSystemFileChooserTest.java

@@ -89,10 +89,39 @@ public class FlatSystemFileChooserTest
 		currentDirCheckBox.setSelected( state.getBoolean( "systemfilechooser.currentdir.enabled", false ) );
 		selectedFileCheckBox.setSelected( state.getBoolean( "systemfilechooser.selectedfile.enabled", false ) );
 		selectedFilesCheckBox.setSelected( state.getBoolean( "systemfilechooser.selectedfiles.enabled", false ) );
+		persistStateCheckBox.setSelected( state.getBoolean( "systemfilechooser.persistState.enabled", false ) );
 
 		currentDirChanged();
 		selectedFileChanged();
 		selectedFilesChanged();
+		persistStateChanged();
+	}
+
+	private void persistStateChanged() {
+		boolean b = persistStateCheckBox.isSelected();
+
+		SystemFileChooser.setStateStore( b
+			? new SystemFileChooser.StateStore() {
+				private static final String KEY_PREFIX = "fileChooser.";
+
+				@Override
+				public String get( String key, String def ) {
+					String value = DemoPrefs.getState().get( KEY_PREFIX + key, def );
+					System.out.println( "GET " + key + " = " + value );
+					return value;
+				}
+
+				@Override
+				public void put( String key, String value ) {
+					System.out.println( "PUT " + key + " = " + value );
+					if( value != null )
+						DemoPrefs.getState().put( KEY_PREFIX + key, value );
+					else
+						DemoPrefs.getState().remove( KEY_PREFIX + key );
+				}
+			} : null );
+
+		DemoPrefs.getState().putBoolean( "systemfilechooser.persistState.enabled", b );
 	}
 
 	private void open() {
@@ -221,6 +250,9 @@ public class FlatSystemFileChooserTest
 //		fc.putPlatformProperty( SystemFileChooser.MAC_OPTIONS_CLEAR, FlatNativeMacLibrary.FC_showsTagField );
 
 //		fc.putPlatformProperty( SystemFileChooser.LINUX_OPTIONS_CLEAR, FlatNativeLinuxLibrary.FC_create_folders | FlatNativeLinuxLibrary.FC_do_overwrite_confirmation );
+
+		String id = (String) stateStoreIDField.getSelectedItem();
+		fc.setStateStoreID( id != null && !id.isEmpty() ? id : null );
 	}
 
 	private void configureSwingFileChooser( JFileChooser fc ) {
@@ -517,6 +549,9 @@ public class FlatSystemFileChooserTest
 		multiSelectionEnabledCheckBox = new JCheckBox();
 		useFileHidingCheckBox = new JCheckBox();
 		useSystemFileChooserCheckBox = new JCheckBox();
+		persistStateCheckBox = new JCheckBox();
+		JLabel stateStoreIDLabel = new JLabel();
+		stateStoreIDField = new JComboBox<>();
 		JLabel approveButtonTextLabel = new JLabel();
 		approveButtonTextField = new JTextField();
 		JLabel approveButtonMnemonicLabel = new JLabel();
@@ -605,6 +640,8 @@ public class FlatSystemFileChooserTest
 				"[]0" +
 				"[]0" +
 				"[]" +
+				"[]para" +
+				"[]" +
 				"[]"));
 
 			//---- directorySelectionCheckBox ----
@@ -624,6 +661,24 @@ public class FlatSystemFileChooserTest
 			useSystemFileChooserCheckBox.setText("use SystemFileChooser");
 			useSystemFileChooserCheckBox.setSelected(true);
 			panel1.add(useSystemFileChooserCheckBox, "cell 0 3");
+
+			//---- persistStateCheckBox ----
+			persistStateCheckBox.setText("persist state");
+			persistStateCheckBox.addActionListener(e -> persistStateChanged());
+			panel1.add(persistStateCheckBox, "cell 0 4");
+
+			//---- stateStoreIDLabel ----
+			stateStoreIDLabel.setText("ID:");
+			panel1.add(stateStoreIDLabel, "cell 0 5");
+
+			//---- stateStoreIDField ----
+			stateStoreIDField.setModel(new DefaultComboBoxModel<>(new String[] {
+				"abc",
+				"def"
+			}));
+			stateStoreIDField.setEditable(true);
+			stateStoreIDField.setSelectedIndex(-1);
+			panel1.add(stateStoreIDField, "cell 0 5,growx");
 		}
 		add(panel1, "cell 2 1 1 7,aligny top,growy 0");
 
@@ -806,6 +861,8 @@ public class FlatSystemFileChooserTest
 	private JCheckBox multiSelectionEnabledCheckBox;
 	private JCheckBox useFileHidingCheckBox;
 	private JCheckBox useSystemFileChooserCheckBox;
+	private JCheckBox persistStateCheckBox;
+	private JComboBox<String> stateStoreIDField;
 	private JTextField approveButtonTextField;
 	private JTextField approveButtonMnemonicField;
 	private JCheckBox currentDirCheckBox;

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatSystemFileChooserTest.jfd

@@ -71,7 +71,7 @@ new FormModel {
 			add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 				"$layoutConstraints": "insets 2,hidemode 3"
 				"$columnConstraints": "[left]"
-				"$rowConstraints": "[]0[]0[][]"
+				"$rowConstraints": "[]0[]0[][]para[][]"
 			} ) {
 				name: "panel1"
 				add( new FormComponent( "javax.swing.JCheckBox" ) {
@@ -112,6 +112,37 @@ new FormModel {
 				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 					"value": "cell 0 3"
 				} )
+				add( new FormComponent( "javax.swing.JCheckBox" ) {
+					name: "persistStateCheckBox"
+					"text": "persist state"
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
+					addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "persistStateChanged", false ) )
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 0 4"
+				} )
+				add( new FormComponent( "javax.swing.JLabel" ) {
+					name: "stateStoreIDLabel"
+					"text": "ID:"
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 0 5"
+				} )
+				add( new FormComponent( "javax.swing.JComboBox" ) {
+					name: "stateStoreIDField"
+					"model": new javax.swing.DefaultComboBoxModel {
+						selectedItem: "abc"
+						addElement( "abc" )
+						addElement( "def" )
+					}
+					"editable": true
+					"selectedIndex": -1
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 0 5,growx"
+				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 2 1 1 7,aligny top,growy 0"
 			} )