How do I created tab delimited data file in Java?

By Wayan in IO 0 Comment

The following code snippet show you how to create a tab delimited data file in Java. The tab character is represented using the \t sequence of characters, a backslash (\) character followed by the t letter. In the code below we start by defining some data that we are going to write to the file.

We create a PrintWriter object, passes a BufferedWritter created using the Files.newBufferedWriter() method. The countries.dat is the file name where the data will be written. Because we are using the try-with-resources the PrintWriter and the related object will be closed automatically when the file operation finishes.

package org.kodejava.io;

import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;

public class TabDelimitedDataFile {
    public static void main(String[] args) throws IOException {
        List<String[]> data = new ArrayList<>();
        data.add(new String[]{"Afghanistan", "AF", "AFG", "004", "Asia"});
        data.add(new String[]{"Åland Islands", "AX", "ALA", "248", "Europe"});
        data.add(new String[]{"Albania", "AL", "ALB", "008", "Europe"});
        data.add(new String[]{"Algeria", "DZ", "DZA", "012", "Africa"});
        data.add(new String[]{"American Samoa", "AS", "ASM", "016", "Polynesia"});
        data.add(new String[]{"Andorra", "AD", "AND", "020", "South Europe"});
        data.add(new String[]{"Angola", "AO", "AGO", "024", "Africa"});
        data.add(new String[]{"Anguilla", "AI", "AIA", "660", "Americas"});
        data.add(new String[]{"Antarctica", "AQ", "ATA", "010", ""});
        data.add(new String[]{"Argentina", "AR", "ARG", "032", "Americas"});

        try (PrintWriter writer = new PrintWriter(
                Files.newBufferedWriter(Paths.get("countries.dat")))) {
            for (String[] row : data) {
                writer.printf("%1$20s\t%2$3s\t\t%3$3s\t\t%4$3s\t\t%5$s",
                        row[0], row[1], row[2], row[3], row[4]);
                writer.println();
            }
        }
    }
}

The output of the code snippet above are:

         Afghanistan     AF     AFG     004     Asia
       Åland Islands     AX     ALA     248     Europe
             Albania     AL     ALB     008     Europe
             Algeria     DZ     DZA     012     Africa
      American Samoa     AS     ASM     016     Polynesia
             Andorra     AD     AND     020     South Europe
              Angola     AO     AGO     024     Africa
            Anguilla     AI     AIA     660     Americas
          Antarctica     AQ     ATA     010     
           Argentina     AR     ARG     032     Americas

How do I move focus from JTextArea using TAB key?

By Wayan in Swing 6 Comments

The default behavior when pressing the tabular key in a JTextArea is to insert a tab spaces in the text area. In this example you’ll see how to change this to make the tab key to transfer focus to other component forward or backward.

The main routine can be found in the key listener section. When the tab key is pressed we will tell the text area to transfer to focus into other component. Let’s see the code snippet below.

package org.kodejava.swing;

import javax.swing.JFrame;
import javax.swing.JPasswordField;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import java.awt.BorderLayout;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

public class TextAreaTabMoveFocus extends JFrame {
    public TextAreaTabMoveFocus() {
        initialize();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(
                () -> new TextAreaTabMoveFocus().setVisible(true));
    }

    private void initialize() {
        setSize(500, 200);
        setTitle("JTextArea TAB DEMO");
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        JTextField textField = new JTextField();
        JPasswordField passwordField = new JPasswordField();
        final JTextArea textArea = new JTextArea();
        JScrollPane scrollPane = new JScrollPane(textArea);

        // Add key listener to change the TAB behavior in
        // JTextArea to transfer focus to other component forward
        // or backward.
        textArea.addKeyListener(new KeyAdapter() {
            @Override
            public void keyPressed(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_TAB) {
                    if (e.getModifiersEx() > 0) {
                        textArea.transferFocusBackward();
                    } else {
                        textArea.transferFocus();
                    }
                    e.consume();
                }
            }
        });

        getContentPane().add(textField, BorderLayout.NORTH);
        getContentPane().add(scrollPane, BorderLayout.CENTER);
        getContentPane().add(passwordField, BorderLayout.SOUTH);
    }
}

The output of the code snippet above is:

JTextArea Move Focus Using Tab

How do I change JTabbedPane tab placement position?

By Wayan in Swing 0 Comment

By default, the tabs in a JTabbedPane component is placed on the top. But you can place the tabs on every side of the JTabbedPane component, for example it can be on the top, on the right, on the left or on the bottom of the JTabbedPane.

To change the tab placement position you need to set the tab placement when creating an instance of JTabbedPane. The tab placement can be set using the following constant values: JTabbedPane.TOP, JTabbedPane.RIGHT, JTabbedPane.LEFT and JTabbedPane.BOTTOM.

Let’s see the following code snippet to demonstrate it.

package org.kodejava.swing;

import javax.swing.*;
import java.awt.*;

public class TabbedPaneTabPlacement extends JPanel {
    public TabbedPaneTabPlacement() {
        initializeUI();
    }

    public static void showFrame() {
        JPanel panel = new TabbedPaneTabPlacement();
        panel.setOpaque(true);

        JFrame frame = new JFrame("Tabbed Pane Tab Placement Demo");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setContentPane(panel);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(TabbedPaneTabPlacement::showFrame);
    }

    private void initializeUI() {
        this.setLayout(new BorderLayout());
        this.setPreferredSize(new Dimension(500, 200));

        // Creates a JTabbedPane with tabs at the bottom.
        JTabbedPane pane = new JTabbedPane(JTabbedPane.BOTTOM);
        pane.addTab("Tab 1", createPanel("Panel 1"));
        pane.addTab("Tab 1", createPanel("Panel 2"));
        pane.addTab("Tab 3", createPanel("Panel 3"));

        this.add(pane, BorderLayout.CENTER);
    }

    private JPanel createPanel(String title) {
        JPanel panel = new JPanel();
        panel.setLayout(new BorderLayout());
        panel.add(new JLabel(title), BorderLayout.NORTH);
        return panel;
    }
}

And here is the result of the code snippet above.

JTabbedPane Tab Position Demo