test/jdk/java/util/TimeZone/DefaultTimeZoneTest.java

/*
 * Copyright (c) 2005, 2025, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 4296930 5033603 7092679
 * @summary Ensure that Java detects the platform time zone correctly, even
 * if changed during runtime. Also ensure that the system time zone detection code
 * detects the "Automatically adjust clock for daylight saving changes" setting
 * correctly on Windows. This is a manual test dependent on making changes to
 * the platform setting of the machine and thus cannot be automated.
 * @library /java/awt/regtesthelpers
 * @build PassFailJFrame
 * @run main/manual DefaultTimeZoneTest
 */

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
import javax.swing.BoxLayout;
import javax.swing.Box;
import java.awt.Dimension;
import java.awt.Component;
import java.awt.BorderLayout;
import java.awt.Window;
import java.lang.reflect.InvocationTargetException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;

public class DefaultTimeZoneTest  {

    private static final SimpleDateFormat SDF =
            new SimpleDateFormat("yyyy-MM-dd HH:mm:ss zzzz (XXX)");
    private static final String INSTRUCTIONS =
            """
            Tests the platform time zone detection on all platforms.
            (Part I) and on/off of DST adjustment on Windows (Part II).

            Part I:
            Observe the displayed Time zone ID and the local time.
            Change the platform time zone setting, then click the
            "Update Time Zone" button. If the ID and local time
            update correctly, part I passes, otherwise press fail. Note that
            some time zone IDs have their aliases that may be displayed.
            For example, "US/Pacific" is an alias of "America/Los_Angeles".
            If this platform is Windows, proceed to Part II. Otherwise, press
            the Pass button to complete this test.

            Part II:
            Note that Part II may require the Administrator privilege to change
            Windows setting.

              1. Open the Settings app and navigate to Time & Language > Date & Time
              2. Select any time zone where daylight saving time is *currently*
                 in effect, such as "(GMT-08:00) Pacific Time (US & Canada);
                 Tijuana", "(GMT+10:00) Canberra, Melbourne, Sydney", and Apply.
              3. After pressing "Update Time Zone" button, observe that the local
                 time on the Settings app and the test local time are the same (daylight time).
              4. Turn off "Adjust for daylight saving time automatically"
              5. Observe the two local times should be the same (standard time).
              6. Turn on "Adjust for daylight saving time automatically"

            If the local time in the Settings app and test window are always the same,
            then this test passes. Press the Pass or Fail button based on the Part II
            result and complete the test.
           """;

    public static void main(String[] args)
            throws InterruptedException, InvocationTargetException {
        // Force platform time zone as default time zone
        TimeZone.setDefault(null);
        System.setProperty("user.timezone", "");
        // Construct test window
        PassFailJFrame.builder()
                .title("DefaultTimeZoneTest Instructions")
                .testUI(createTest())
                .instructions(INSTRUCTIONS)
                .build().awaitAndCheck();
    }

    private static Window createTest() {
        var contents = new JFrame("DefaultTimeZoneTest");
        contents.setSize(350, 250);
        // Panel with vertical layout
        var panel = new JPanel();
        panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
        // Time zone ID label
        var timeZoneID = new JLabel("Time zone ID: " + SDF.getTimeZone().getID(), SwingConstants.CENTER);
        timeZoneID.setAlignmentX(Component.CENTER_ALIGNMENT);
        // Time label
        var label = new JLabel(SDF.format(new Date()), SwingConstants.CENTER);
        label.setAlignmentX(Component.CENTER_ALIGNMENT);
        // Update button
        var button = new JButton("Update Time Zone");
        button.setAlignmentX(Component.CENTER_ALIGNMENT);
        // Add components with spacing
        panel.add(Box.createRigidArea(new Dimension(0, 10)));
        panel.add(timeZoneID);
        panel.add(Box.createRigidArea(new Dimension(0, 5)));
        panel.add(label);
        panel.add(Box.createRigidArea(new Dimension(0, 10)));
        panel.add(button);
        contents.add(panel);

        // Update default time zone on button click
        button.addActionListener(e -> {
            // Clear JVM cached timezone and force reload from OS
            TimeZone.setDefault(null);
            System.setProperty("user.timezone", "");
            TimeZone tz = TimeZone.getDefault();
            SDF.setTimeZone(tz);
            timeZoneID.setText("Time zone ID: " + tz.getID());
            label.setText(SDF.format(new Date()));
            contents.repaint();
        });
        return contents;
    }
}