Rakoczi Markus

Thanks for all your replies, it was a great help to me!

No, the Node class doesn't have any superclass (except the Object), and the getData() method returns a String.

Hello,

I need to create a Node class for a binary tree with String data, here follows my class

public class Node<String> implements Comparable<Node>{ String data = null; Node leftChild = null; Node rightChild = null; public Node(String _data) { this.data = _data; } public Node(String _data, Node _leftChild, Node _rightChild){ this.data = _data; this.setLeftChild(_leftChild); this.setRightChild(_rightChild); } public void setLeftChild(Node _leftChild){ this.leftChild = _leftChild; } public void setRightChild(Node _rightChild){ this.rightChild = _rightChild; } public String getData(){ return this.data; } @Override public int compareTo(Object _otherNode) throws ClassCastException{ if (!(_otherNode instanceof Node)) { throw new ClassCastException("Node object expected for compareTo() method."); } return this.data.compareTo(((Node)_otherNode).getData()); // THE PROBLEM IS HERE } }

I got the following hints on the commented line

cannot find symbol
symbol: method compareTo(Object)
location: variable data of type String
where String is a type-variable:
String extends Object declared in class Node
----
(Alt-Enter shows hints)

the error at compile time is:
error: cannot find symbol return this.data.compareTo(((Node)_otherNode).getData());
symbol: method compareTo(Object)
location: variable data of type String where String is a type-variable: String extends Object declared in class Node

what's wrong with my code?

Hello,

my question is about GC.
Suppose I have an acyclic double linked list like: Start<->A<->B<->C<-> ... <->NULL. If I set Start->Null, will be the rest of the list eligible for garbage collection or not?
What happens if I have a circular linked list? Should I set each object next and prev to null to be eligible for garbage collection?

Thanks.

Hello,
i think you should wrap in an Anchor pane and bind it to the margins.

There are files in the .mozilla folder where you don't have access or maybe they are temporary in the Cache folder . (Actually if I stop Firefox the program doesn't give error on .mozilla folder).
The solution was to handle the java.nio.file.NoSuchFileException

Thanks for everyone, problem solved!

surlac surlacovich wrote:

Rakoczi Markus wrote:
my problem is when i start the program it visits only 5 directories with it's subdirectories, but in my /home folder there are much more directories.
What's wrong with my implementation?

There must be no files in "home" folder and it's subfolders.

Sorry, but what do you mean by "no files in home folder and it's subfolders" ?

@Mansukhdeep Thind

Here is a picture with folder content :


In the source code on my computer of course the path is "/home/myUserName" and the screenshot as well.

only the folders below are visited
.thumbnails
.macromedia
Workspace
.netbeans
.mozilla

in .mozilla folder at one point i get the following ERROR:

java.nio.file.NoSuchFileException: /home/myUserName/.mozilla/firefox/mwad0hks.default/lock
at sun.nio.fs.UnixException.translateToIOException(UnixException.java:86)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
at sun.nio.fs.UnixFileAttributeViews$Basic.readAttributes(UnixFileAttributeViews.java:55)
at sun.nio.fs.UnixFileSystemProvider.readAttributes(UnixFileSystemProvider.java:143)
at sun.nio.fs.LinuxFileSystemProvider.readAttributes(LinuxFileSystemProvider.java:96)
at java.nio.file.Files.readAttributes(Files.java:1675)
at java.nio.file.Files.size(Files.java:2264)
at test_files.Test_Files$1.visitFile(Test_Files.java:36)
at test_files.Test_Files$1.visitFile(Test_Files.java:32)
at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:135)
at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:199)
at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:199)
at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:199)
at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:199)
at java.nio.file.FileTreeWalker.walk(FileTreeWalker.java:69)
at java.nio.file.Files.walkFileTree(Files.java:2591)
at java.nio.file.Files.walkFileTree(Files.java:2624)
at test_files.Test_Files.main(Test_Files.java:32)

Hello,

i have the following code:

public class Test_Files { public static void main(String[] args) { try { Path searchPath = Paths.get("/home"); Files.walkFileTree(searchPath, new SimpleFileVisitor<Path>() { @Override public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException { System.out.println("File name is: " + file.toString() + " - size is: " + Files.size(file) / (1024 * 1024) + " MB"); return FileVisitResult.CONTINUE; } @Override public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException { System.out.println("ERROR - visiting file: " + file.toString()); return FileVisitResult.CONTINUE; } }); } catch (IOException ex) { Logger.getLogger(Test_Files.class.getName()).log(Level.SEVERE, null, ex); } } }

my problem is when i start the program it visits only 5 directories with it's subdirectories, but in my /home folder there are much more directories.
What's wrong with my implementation?

Hello

I not experienced with regex expresions, and i want to check if a textfield contains white spaces, so i read the textfield content and matches with a regex expression
for example:

final static String WHITE_SPACES = "\\s*"; textFieldContent.matches(WHITE_SPACES);

is my regex expression complete enough to check for any posibile white space content?

Thanks.

Thank you, thank you - it's working.

Hello,

i have a program that should load images from a selected folder and add them to a TilePane, all the loading process it's made within a Task. My problem is when the image loading thread want's to access the TilePane it stops. How should i implement this to work well and fast with folders where there are up to 50-60 images each one more than 2 MB.

import java.io.File; import java.io.FileFilter; import java.io.FileInputStream; import java.io.FileNotFoundException; import javafx.application.Application; import javafx.concurrent.Task; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.geometry.Insets; import javafx.scene.Scene; import javafx.scene.control.Button; import javafx.scene.image.Image; import javafx.scene.image.ImageView; import javafx.scene.image.ImageViewBuilder; import javafx.scene.layout.BorderPane; import javafx.scene.layout.BorderPaneBuilder; import javafx.scene.layout.TilePane; import javafx.scene.layout.TilePaneBuilder; import javafx.stage.DirectoryChooser; import javafx.stage.Stage; public class LoadImage extends Application { // a TilePane for image thumbnails final TilePane tilePane = TilePaneBuilder.create() .padding(new Insets(20, 10, 10, 10)) .hgap(4) .vgap(4) .build(); @Override public void start(final Stage primaryStage) { primaryStage.setTitle("TilePane with ImageView"); //create a border pane - center with TilePane for thubmnails and bottom for Button BorderPane borderPane = BorderPaneBuilder.create() .prefHeight(400) .prefWidth(600) .build(); //create Button for load location with images Button loadButton = new Button("Load"); loadButton.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { //create a task to load images Thread loadImageThread = new Thread(task); loadImageThread.setDaemon(true); loadImageThread.start(); } }); borderPane.setCenter(tilePane); borderPane.setBottom(loadButton); Scene scene = new Scene(borderPane); primaryStage.setScene(scene); primaryStage.show(); } Task<Void> task = new Task<Void>() { @Override protected Void call() throws Exception { DirectoryChooser directoryChooser = new DirectoryChooser(); final File selectedDirectory = directoryChooser.showDialog(null); //there is an ImageFileFilter class below File[] imageFiles = selectedDirectory.listFiles(new ImageFileFilter()); tilePane.getChildren().clear(); for (File file : imageFiles) { try { ImageView imageView = ImageViewBuilder.create() .preserveRatio(true) .fitHeight(128) .fitWidth(128) .image(new Image(new FileInputStream(file))) .build(); //add imageView to the TilePane tilePane.getChildren().add(imageView); } catch (FileNotFoundException e) { e.printStackTrace(); } } return null; } }; public static void main(String[] args) { launch(args); } private class ImageFileFilter implements FileFilter { private final String[] validFileExtension = new String[] {"jpg", "jpeg", "png", "gif"}; @Override public boolean accept(File pathname) { for (String extension : validFileExtension) { if (pathname.getName().toLowerCase().endsWith(extension)) { return true; } } return false; } } }

Hello,

i want to create a small image file browser (using java swing) that outputs image thumbnails in one of the window area (the green area in the attached picture). What would be the proper swing component, to implement the respectiv area JTable or JPanel with JButtons, any other suggestion?
I want to implement operations like select, right click with mouse, or change color when the cursor is on the thumbnail.