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File preview and checking in file chooser



It is possible to add a preview in a file chooser to throw an eye at the files during the selection.

chooser = new JFileChooser(Settings.getProperty("heterofor.species.path", PathManager.getInstallDir()));
new FileAccessory(chooser);

The preview (here on the right side) tries to shows the file content


It is also possible to use the CheckingFileChooser instead of the JFileChooser to check during selection which files will be loaded without error. The process relies on a method to be redefined called check (File f). When the file given to this method is correct, the method must return true.

The result is a green check mark associated to each correct file, and a red mark for those which will not load correctly.

The Preview is always shown in the CheckingFileChooser, it will show the mark for the selected file.

Warning: some Java look and feels do not show the icon for each file during selection (e.g. GTK+ under Linux). In this case, the mark can still be seen in the FileAccessory preview.

// fc-4.12.2017 A file chooser showing which files can be loaded
JFileChooser chooser = new CheckingFileChooser(Settings.getProperty("capsis.inventory.path",
		PathManager.getDir("data"))) {
	public boolean check(File f) {
		String fileName = f.getAbsolutePath();
		try {
			// Use fake objects to avoid side effects
			Samsa2Model modelFake = new Samsa2Model();
			Samsa2InitialParameters ipFake = modelFake.getSettings();
			// Check if the file can be loaded
			ipFake.vParamMS.virtualStand = false;
			ipFake.fileName = fileName;
			// Seems ok
			return true;
		} catch (Throwable e) {
			// Seems problematic
			return false;

The green and red marks in Windows' Look & FeelA green mark shows which file will be loaded correctlyUnder GTK+ L&F, the mark can be seen in the file preview

Fast checking

This is a proposal of a simple check () implementation for the CheckingFileChooser when the file is to be loaded by a RecordSet / FileLoader.

It will check the file format interpretation by the loader but will not go further: an error might still happen later during effective file loading, when interpreting the content of the fields and lines.

Note: jeeb.lib.util.RecordSet is a tool to build text file loaders quickly, by specifying the expected line formats in objects extending the Record class. Giving a fileName to the tool, it will use introspection to check if the lines match the given Records and turn the file into a List of Records, easying their interpretation in a load () method called after.

See also jeeb.lib.util.fileloader.FileLoader for a variant.

String path = inventoryFileName.getText();
JFileChooser chooser = new CheckingFileChooser(path) {
	public boolean check(File file) {
		try {
			// Just checks if the loader loads, do not check until Plot creation
			new Lub2InventoryLoader(file.getAbsolutePath());
			return true;
		} catch (Exception e) {
			return false;
new FileAccessory(chooser);

The files with a green mark are supposed to be loaded correctly if selected

file_preview_and_checking_in_file_chooser.1512575209.txt ยท Last modified: 2017/12/06 15:46 by coligny