How do I get the selected color from JColorChooser?

By I Wayan Saryada in Swing 0 Comment

To get the selected color from JColorChooser we need to create an implementation of the ChangeListener interface. This interface provides a single method call stateChanged(ChangeEvent e). The instance of this interface implementation need to be passed to JColorChooser by calling the JColorChooser.getSelectionModel().addChangeListener() method.

In this example our ChangeListener implementation get the selected color and replace the foreground color the JLabel component.

package org.kodejava.swing;

import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.*;

public class JColorChooserColorSelection extends JFrame {
    private JColorChooser jcc = null;
    private JLabel label = null;

    public JColorChooserColorSelection() {
        initializeUI();
    }

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

    private void initializeUI() {
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        jcc = new JColorChooser();
        jcc.getSelectionModel().addChangeListener(new ColorSelection());
        getContentPane().add(jcc, BorderLayout.PAGE_START);

        label = new JLabel("Selected Font Color", JLabel.CENTER);
        label.setFont(new Font("SansSerif", Font.BOLD, 24));
        label.setForeground(Color.BLACK);
        label.setPreferredSize(new Dimension(100, 100));
        getContentPane().add(label, BorderLayout.CENTER);
        this.pack();
    }

    /**
     * A ChangeListener implementation for listening the color
     * selection of the JColorChooser component.
     */
    class ColorSelection implements ChangeListener {
        public void stateChanged(ChangeEvent e) {
            Color color = jcc.getColor();
            label.setForeground(color);
        }
    }
}

JColorChooser get selected color

How do I use JColorChooser component?

By I Wayan Saryada in Swing 0 Comment

The JColorChooser is a Swing component that provides a palette from where we can select a color code in RGB format. The JColorChooser component has two parts, the tabbed pane of color selection and a preview box. The tabbed has three tabs which allows us to select a color from a swatches, a HSB (Hue, Saturation and Brightness) combination and an RGB (Red Blue Green) color combination.

package org.kodejava.swing;

import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.*;

public class JColorChooserDemo extends JFrame implements ChangeListener {
    private JColorChooser colorChooser = null;

    public JColorChooserDemo() throws HeadlessException {
        initUI();
    }

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

    private void initUI() {
        // Set title and default close operation of this JFrame.
        setTitle("JColorChooser Demo");
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        // Creates an instance of JColorChooser component and
        // adds it to the frame's content.
        colorChooser = new JColorChooser();
        getContentPane().add(colorChooser, BorderLayout.PAGE_END);

        // Add a change listener to get the selected color in this
        // JColorChooser component.
        colorChooser.getSelectionModel().addChangeListener(this);
        this.pack();
    }

    /**
     * Handles color selection in the JColorChooser component.
     *
     * @param e the ChangeEvent
     */
    public void stateChanged(ChangeEvent e) {
        // Get the selected color in the JColorChooser component
        // and print the color in RGB format to the console.
        Color color = colorChooser.getColor();
        System.out.println("color = " + color);
    }
}

When you run the program above a frame with JColorChooser component will be shown. A string of the color code in an RGB format will be printed in the console if you click a color from the color selection.

Here is an image of a JColorChooser component.

JColorChooser Component Demo

How do I change the date format symbols for a specified locale?

By I Wayan Saryada in Core API, Text Package 0 Comment 
package org.kodejava.text;

import java.text.DateFormatSymbols;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class ChangeDateFormatSymbols {
    public static void main(String[] args) {
        Locale id = new Locale("in", "ID");
        String pattern = "EEEE, dd MMM yyyy";
        Date today = new Date();

        // Gets formatted date specify by the given pattern for
        // Indonesian Locale no changes for default date format
        // is applied here.
        SimpleDateFormat sdf = new SimpleDateFormat(pattern, id);
        String before = sdf.format(today);
        System.out.println("Before format change: " + before);

        // Create a DateFormatSymbols object for Indonesian locale.
        DateFormatSymbols dfs = new DateFormatSymbols(id);

        // Gets String array of default format of weekdays.
        String[] days = dfs.getWeekdays();
        String[] newDays = new String[days.length];
        for (int i = 0; i < days.length; i++) {
            // For each day, apply toUpperCase() method to
            // capitalized it.
            newDays[i] = days[i].toUpperCase();
        }

        // Set String array of weekdays.
        dfs.setWeekdays(newDays);

        // Gets String array of default format of short months.
        String[] shortMonths = dfs.getShortMonths();
        String[] months = new String[shortMonths.length];
        for (int j = 0; j < shortMonths.length; j++) {
            // For each short month, apply toUpperCase() method
            // to capitalized it.
            months[j] = shortMonths[j].toUpperCase();
        }

        // Set String array of short months.
        dfs.setShortMonths(months);

        // Create a SimpleDateFormat object by given pattern and 
        // symbol and then format the date object as String.
        sdf = new SimpleDateFormat(pattern, dfs);
        String after = sdf.format(today);
        System.out.println("After change format : " + after);
    }
}

Here are the output of our program:

Before format change: Selasa, 19 Okt 2021
After change format : SELASA, 19 OKT 2021

How do I get a formatted date for a specific pattern and locale?

By I Wayan Saryada in Core API, Text Package 0 Comment

If you want to change formatting styles provided by DateFormat, you can use SimpleDateFormat class. The SimpleDateFormat class is locale-sensitive.

If you instantiate SimpleDateFormat without a Locale parameter, it will format the date and time according to the default Locale. Both the pattern and the Locale determine the format. For the same pattern, SimpleDateFormat may format a date and time differently if the Locale varies.

package org.kodejava.text;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class SimpleDateFormatChangeLocalePattern {
    public static void main(String[] args) {
        String pattern = "dd-MMM-yyyy";
        Date today = new Date();

        // Gets a formatted date according to the given pattern.
        // Here only the pattern is passed as argument of the
        // SimpleDateFormat constructor, so it will format the
        // date according to the default Locale.
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        String local = sdf.format(today);
        System.out.println("Date in default locale: " + local);

        Locale[] locales = {
                Locale.CANADA,
                Locale.FRANCE,
                Locale.GERMANY,
                Locale.US,
                Locale.JAPAN
        };

        for (Locale locale : locales) {
            // Format a date according to the given pattern for each locale.
            sdf = new SimpleDateFormat(pattern, locale);
            String after = sdf.format(today);
            System.out.println(locale.getDisplayCountry() + " | format: " + after);
        }
    }
}

Here are the variety of output produces when formatting a date in the same date pattern but varies in Locale

Date in default locale: 19-Oct-2021
Canada | format: 19-Oct.-2021
France | format: 19-oct.-2021
Germany | format: 19-Okt.-2021
United States | format: 19-Oct-2021
Japan | format: 19-10月-2021

How do I get default date and time format for a defined country?

By I Wayan Saryada in Core API, Text Package 0 Comment

The DateFormat class allows you to format dates and times with predefined styles in a locale-sensitive manner. Formatting dates or times with the DateFormat class is a two-step process.

First, you create a formatter with the getDateInstance() method for formatting date or getTimeInstance() method for formatting time or getDateTimeInstance() when you want formatting both date and time.

Second, you invoke the format method, which returns a String containing the formatted date. The following example formats today’s date and time by calling those two methods.

package org.kodejava.text;

import java.text.DateFormat;
import java.util.Date;
import java.util.Locale;

public class LocaleDateTime {
    public static void main(String[] args) {
        Locale[] locales = {
                Locale.CANADA, Locale.FRANCE, Locale.GERMANY, Locale.US, 
                Locale.JAPAN
        };

        Date today = new Date();
        for (Locale locale : locales) {
            StringBuilder sb = new StringBuilder();
            sb.append(locale.getDisplayCountry()).append(System.lineSeparator());
            sb.append("------------------------").append(System.lineSeparator());

            // Gets a DateFormat instance for the specified locale
            // and format a date object by calling the format method.
            DateFormat df = DateFormat.getDateInstance(DateFormat.DEFAULT, locale);
            String date = df.format(today);
            sb.append("Default date format: ").append(date)
                    .append(System.lineSeparator());

            // Gets a DateFormat instance for the specified locale
            // and format a time information by calling the format method.
            DateFormat tf = DateFormat.getTimeInstance(DateFormat.DEFAULT, locale);
            String time = tf.format(today.getTime());
            sb.append("Default time format: ").append(time)
                    .append(System.lineSeparator());

            System.out.println(sb);
        }

        // Gets date and time formatted value for Italy locale using
        // To display a date and time in the same String, create the
        // formatter with the getDateTimeInstance method.
        // The first parameter is the date style, and the second is
        // the time style. The third parameter is the Locale
        DateFormat dtf = DateFormat.getDateTimeInstance(DateFormat.DEFAULT,
                DateFormat.DEFAULT, Locale.ITALY);
        String datetime = dtf.format(today);

        System.out.println("date time format in " +
                Locale.ITALY.getDisplayCountry() + ": " + datetime);
    }
}

Here are the produces output:

Canada
------------------------
Default date format: Oct. 19, 2021
Default time format: 6:11:45 a.m.

France
------------------------
Default date format: 19 oct. 2021
Default time format: 06:11:45

Germany
------------------------
Default date format: 19.10.2021
Default time format: 06:11:45

United States
------------------------
Default date format: Oct 19, 2021
Default time format: 6:11:45 AM

Japan
------------------------
Default date format: 2021/10/19
Default time format: 6:11:45

date time format in Italy: 19 ott 2021, 06:11:45