How do I create a console progress bar?

By Wayan in Core API, Lang Package 1 Comment

The code below demonstrates how to create a progress bar in a console program. The trick is to print the progress status using a System.out.print() and add a carriage return character ("\r") at the end of the string to return the cursor position to the beginning of the line and print the next progress status.

package org.kodejava.lang;

public class ConsoleProgressBar {
    public static void main(String[] args) {
        char[] animationChars = new char[]{'|', '/', '-', '\\'};

        for (int i = 0; i <= 100; i++) {
            System.out.print("Processing: " + i + "% " + animationChars[i % 4] + "\r");

            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        System.out.println("Processing: Done!");
    }
}

How do I calculate process execution time in higher resolution?

By Wayan in Core API, Lang Package 0 Comment

This example demonstrates how to use the System.nanoTime() method to calculate processing execution time in higher resolution. The processing time calculated in nanoseconds resolution.

package org.kodejava.lang;

public class NanoSecondsTimerResolution {
    public static void main(String[] args) {
        // Get process execution start time in nanoseconds.
        long start = System.nanoTime();
        System.out.println("Process start... " + start);

        try {
            Thread.sleep(5000); // Simulate a long process.
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        // Get process execution finish time in nanoseconds.
        long finish = System.nanoTime();
        System.out.println("Process finish... " + finish);

        // Calculate the process execution time.
        long execTime = finish - start;
        System.out.println("Processing time = " + execTime + "(ns)");
    }
}

How do I convert JDOM Document to String?

By Wayan in JDOM 0 Comment

This example demonstrate how to convert JDOM Document object to a String using the XMLOutputter.outputString(Document doc) method.

package org.kodejava.jdom;

import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;

public class JDOMDocumentToString {
    public static void main(String[] args) {
        Document document = new Document();
        Element root = new Element("rows");

        // Creating a child for the root element. Here we can see how to
        // set the text of an xml element.
        Element child = new Element("row");
        child.addContent(new Element("firstname").setText("Alice"));
        child.addContent(new Element("lastname").setText("Mallory"));
        child.addContent(new Element("address").setText("Sunset Road"));

        // Add the child to the root element and add the root element as
        // the document content.
        root.addContent(child);
        document.setContent(root);

        // Create an XMLOutputter object with pretty formatter. Calling
        // the outputString(Document doc) method convert the document
        // into string data.
        XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat());
        String xmlString = outputter.outputString(document);
        System.out.println(xmlString);
    }
}

The result of our code snippet:

<?xml version="1.0" encoding="UTF-8"?>
<rows>
  <row>
    <firstname>Alice</firstname>
    <lastname>Mallory</lastname>
    <address>Sunset Road</address>
  </row>
</rows>

Maven Dependencies

<dependency>
    <groupId>org.jdom</groupId>
    <artifactId>jdom2</artifactId>
    <version>2.0.6.1</version>
</dependency>

Maven Central

How do I get the default print service?

By Wayan in Core API, Print Service 0 Comment

To look up the default print service we can use the javax.print.PrintServiceLookup class lookupDefaultPrintService() method.

package org.kodejava.print;

import javax.print.PrintService;
import javax.print.PrintServiceLookup;

public class GetPrinter {
    public static void main(String[] args) {
        // Gets the default print service for this environment. Null is returned when 
        // no default print service found.
        PrintService service = PrintServiceLookup.lookupDefaultPrintService();
        if (service != null) {
            String printServiceName = service.getName();
            System.out.println("Print Service Name = " + printServiceName);
        } else {
            System.out.println("No default print service found.");
        }
    }
}

The result of the code snippet above:

Print Service Name = HP LaserJet P1005

How do I add background image in JTextPane?

By Wayan in Swing 0 Comment

The example below demonstrate how to create a custom JTextPane component that have a background image.

package org.kodejava.swing;

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Objects;

public class TextPaneWithBackgroundImage extends JFrame {
    public TextPaneWithBackgroundImage() {
        initUI();
    }

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

    private void initUI() {
        setSize(500, 500);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new FlowLayout(FlowLayout.LEFT));

        String imageFile = "/logo.png";
        CustomTextPane textPane = new CustomTextPane(imageFile);

        JScrollPane scrollPane = new JScrollPane(textPane);
        scrollPane.setPreferredSize(new Dimension(getWidth(), getHeight()));
        getContentPane().add(scrollPane);
        pack();
    }
}

/**
 * A custom text pane that have a background image. To customize the
 * JTextPane we override the paintComponent(Graphics g) method. We have
 * to draw an image before we call the super class paintComponent method.
 */
class CustomTextPane extends JTextPane {
    private final String imageFile;

    /**
     * Constructor of custom text pane.
     *
     * @param imageFile image file name for the text pane background.
     */
    CustomTextPane(String imageFile) {
        super();
        // To be able to draw the background image the component must
        // not be opaque.
        setOpaque(false);
        setForeground(Color.BLUE);

        this.imageFile = imageFile;
    }

    @Override
    protected void paintComponent(Graphics g) {
        try {
            // Load an image for the background image of out JTextPane.
            BufferedImage image = ImageIO.read(Objects.requireNonNull(
                    getClass().getResourceAsStream(imageFile)));
            g.drawImage(image, 0, 0, (int) getSize().getWidth(),
                    (int) getSize().getHeight(), this);
        } catch (IOException e) {
            e.printStackTrace();
        }

        super.paintComponent(g);
    }
}

JTextPane background image