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

How do I sort string of numbers in ascending order?

By Wayan in Core API, Util Package 2 Comments

In the following example we are going to sort a string containing the following numbers "2, 5, 9, 1, 10, 7, 4, 8" in ascending order, so we will get the result of "1, 2, 4, 5, 7, 8, 9, 10".

package org.kodejava.util;

import java.util.Arrays;

public class SortStringNumber {
    public static void main(String[] args) {
        // We have some string numbers separated by comma. First we
        // need to split it, so we can get each individual number.
        String data = "2, 5, 9, 1, 10, 7, 4, 8";
        String[] numbers = data.split(",");

        // Convert the string numbers into Integer and placed it into
        // an array of Integer.
        Integer[] intValues = new Integer[numbers.length];
        for (int i = 0; i < numbers.length; i++) {
            intValues[i] = Integer.parseInt(numbers[i].trim());
        }

        // Sort the number in ascending order using the
        // Arrays.sort() method.
        Arrays.sort(intValues);

        // Convert back the sorted number into string using the
        // StringBuilder object. Prints the sorted string numbers.
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < intValues.length; i++) {
            Integer intValue = intValues[i];
            builder.append(intValue);
            if (i < intValues.length - 1) {
                builder.append(", ");
            }
        }
        System.out.println("Before = " + data);
        System.out.println("After  = " + builder);
    }
}

When we run the program we will get the following output:

Before = 2, 5, 9, 1, 10, 7, 4, 8
After  = 1, 2, 4, 5, 7, 8, 9, 10

How do I turn on the Scroll Lock button?

By Wayan in AWT, Core API 0 Comment

The program below show you how to turn on the Scroll Lock button programmatically. Setting the locking state to Boolean.TRUE activate the Scroll Lock.

package org.kodejava.awt;

import java.awt.*;
import java.awt.event.KeyEvent;

public class TurnScrollLockOn {
    public static void main(String[] args) {
        // Gets the default toolkit.
        Toolkit toolkit = Toolkit.getDefaultToolkit();

        // Update the locking state for scroll lock button to true
        // will turn the scroll lock on.
        toolkit.setLockingKeyState(KeyEvent.VK_SCROLL_LOCK, Boolean.TRUE);
    }
}

How do I turn on the Num Lock button?

By Wayan in AWT, Core API 0 Comment

The example below show you how to activate the Num Lock button programmatically. Setting the locking state to Boolean.TRUE will turn the Num Lock on.

package org.kodejava.awt;

import java.awt.Toolkit;
import java.awt.event.KeyEvent;

public class TurnNumLockOn {
    public static void main(String[] args) {
        // Gets the default toolkit.
        Toolkit toolkit = Toolkit.getDefaultToolkit();

        // Update the locking state for num lock button to true
        // will turn the num lock on.
        toolkit.setLockingKeyState(KeyEvent.VK_NUM_LOCK, Boolean.TRUE);
    }
}

How do I turn on the Caps Lock button?

By Wayan in AWT, Core API 0 Comment

The code below show you how to activate the Caps Lock button programmatically. Setting the locking state to Boolean.TRUE will turn the Caps Lock on.

package org.kodejava.awt;

import java.awt.Toolkit;
import java.awt.event.KeyEvent;

public class TurnCapsLockOn {
    public static void main(String[] args) throws Exception {
        // Gets the default toolkit.
        Toolkit toolkit = Toolkit.getDefaultToolkit();

        // Update the locking state for caps lock button to true 
        // will turn the caps lock on.
        toolkit.setLockingKeyState(KeyEvent.VK_CAPS_LOCK, Boolean.TRUE);
    }
}