How do I change the XML root element name in JAXB?

In the following code snippet you will learn how to change the default root element name of the XML generated by the JAXB API. By default, the name of the class is use as the root element name. To change the root element name we can use the name property of the @XmlRootElement annotation. In the Customer model below we change the root element name into cust.

package org.kodejava.xml;

import org.kodejava.xml.support.Address;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlRootElement(name = "cust")
@XmlType(propOrder = {"id", "name", "address"})
public class Customer {
    private Integer id;
    private String name;
    private Address address;

    @XmlElement
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @XmlElement
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @XmlElement
    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}
package org.kodejava.xml.support;

public class Address {
    private String street;
    private String city;
    private String province;
    private String zipcode;
    private String country;

    // Getters & Setters
}
package org.kodejava.xml;

import org.kodejava.xml.support.Address;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class JAXBCustomRootElement {
    public static void main(String[] args) {
        Customer customer = new Customer();
        customer.setId(1);
        customer.setName("Johnny Mnemonic");

        Address address = new Address();
        address.setStreet("Sunset Road");
        address.setCity("Denpasar");
        address.setProvince("Bali");
        address.setZipcode("80225");
        address.setCountry("Indonesia");
        customer.setAddress(address);

        try {
            JAXBContext context = JAXBContext.newInstance(Customer.class);
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
            marshaller.marshal(customer, System.out);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

When we convert this POJO to XML using JAXB API we will get the following result:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<cust>
    <id>1</id>
    <name>Johnny Mnemonic</name>
    <address>
        <city>Denpasar</city>
        <country>Indonesia</country>
        <province>Bali</province>
        <street>Sunset Road</street>
        <zipcode>80225</zipcode>
    </address>
</cust>

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.3.1</version>
    </dependency>    
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-ri</artifactId>
        <version>2.3.5</version>
        <type>pom</type>
    </dependency>
</dependencies>

Maven Central Maven Central

How to create an XML file of a POJO using JAXB?

The code snippet below show you how to convert POJO into XML file using JAXB. To do this we can pass the output file where we want the XML to be saved to the marshaller object.

package org.kodejava.xml;

import org.kodejava.xml.support.Track;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import java.io.File;

public class JAXBObjectToXmlFile {
    public static void main(String[] args) {
        Track track = new Track();
        track.setId(2);
        track.setTitle("She Loves You");

        try {
            JAXBContext context = JAXBContext.newInstance(Track.class);

            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

            File output = new File("Track.xml");
            marshaller.marshal(track, output);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

This snippet will create a file called Track.xml with the following content:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<track id="2">
    <title>She Loves You</title>
</track>
package org.kodejava.xml.support;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Track {
    private Integer id;
    private String title;

    public Track() {
    }

    public Integer getId() {
        return id;
    }

    @XmlAttribute
    public void setId(Integer id) {
        this.id = id;
    }

    @XmlElement
    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    @Override
    public String toString() {
        return "Track{" +
                "id=" + id +
                ", title='" + title + '\'' +
                '}';
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.3.1</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-ri</artifactId>
        <version>2.3.5</version>
        <type>pom</type>
    </dependency>
</dependencies>

Maven Central Maven Central

How to add hours, minutes, seconds into DateTime in Joda-Time?

In this example you will learn how to add hours, minutes or seconds to a DateTime object in Joda-Time. Some methods are available to add or subtract hours, minutes or seconds from the object, as you can see in the example below.

The DateTime object is an immutable object, which means calling one of the plus() or minus() method does not modify the current object. Instead, these methods return a new DateTime object for each method calls.

In the code snippet below we call the plus() and minus() method without storing the result of the operation, we are only going to print it out. The get the new value of the DateTime object you need to assign it to a variable.

package org.kodejava.joda;

import org.joda.time.DateTime;

public class TimeCalculationDemo {
    public static void main(String[] args) {
        // Creates an instance of current DateTime which represents the
        // current date time.
        DateTime dateTime = new DateTime();
        System.out.println("DateTime            = " + dateTime);

        // Plus some hours, minutes, and seconds to the original DateTime.
        System.out.println("Plus 60 seconds is  = " + dateTime.plusSeconds(60));
        System.out.println("Plus 10 minutes is  = " + dateTime.plusMinutes(10));
        System.out.println("Plus 1 hour is      = " + dateTime.plusHours(1));

        // Minus some hours, minutes, and seconds to the original DateTime.
        System.out.println("Minus 60 seconds is = " + dateTime.minusSeconds(60));
        System.out.println("Minus 10 minutes is = " + dateTime.minusMinutes(10));
        System.out.println("Minus 1 hour is     = " + dateTime.minusHours(1));
    }
}

The program print the following result. The output shows the result of adding or subtracting seconds, minutes and hours the the DateTime object.

DateTime            = 2021-10-31T22:56:55.715+08:00
Plus 60 seconds is  = 2021-10-31T22:57:55.715+08:00
Plus 10 minutes is  = 2021-10-31T23:06:55.715+08:00
Plus 1 hour is      = 2021-10-31T23:56:55.715+08:00
Minus 60 seconds is = 2021-10-31T22:55:55.715+08:00
Minus 10 minutes is = 2021-10-31T22:46:55.715+08:00
Minus 1 hour is     = 2021-10-31T21:56:55.715+08:00

Maven Dependencies

<dependency>
    <groupId>joda-time</groupId>
    <artifactId>joda-time</artifactId>
    <version>2.12.7</version>
</dependency>

Maven Central

How do I checks if two dates are on the same day?

In this example, you will learn how to find out if two defined date objects are on the same day. It means that we are only interested in the date information and ignoring the time information of these date objects. We will be using an API provided by the Apache Commons Lang library. So here is the code snippet:

package org.kodejava.commons.lang;

import org.apache.commons.lang3.time.DateUtils;

import java.util.Calendar;
import java.util.Date;

public class CheckSameDay {
    public static void main(String[] args) {
        Date date1 = new Date();
        Date date2 = new Date();

        // Checks to see if the dates is on the same day.
        if (DateUtils.isSameDay(date1, date2)) {
            System.out.printf("%1$te/%1$tm/%1$tY and %2$te/%2$tm/%2$tY " +
                    "is on the same day.%n", date1, date2);
        }

        Calendar cal1 = Calendar.getInstance();
        Calendar cal2 = Calendar.getInstance();

        // Checks to see if the calendars is on the same day.
        if (DateUtils.isSameDay(cal1, cal2)) {
            System.out.printf("%1$te/%1$tm/%1$tY and %2$te/%2$tm/%2$tY " +
                    "is on the same day.%n", cal1, cal2);
        }

        cal2.add(Calendar.DAY_OF_MONTH, 10);
        if (!DateUtils.isSameDay(cal1, cal2)) {
            System.out.printf("%1$te/%1$tm/%1$tY and %2$te/%2$tm/%2$tY " +
                    "is not on the same day.", cal1, cal2);
        }
    }
}

The example results produced by this snippet are:

31/10/2021 and 31/10/2021 is on the same day.
31/10/2021 and 31/10/2021 is on the same day.
31/10/2021 and 10/11/2021 is not on the same day.

Maven Dependencies

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.14.0</version>
</dependency>

Maven Central

How do I change JFrame state programmatically?

In the following code snippet you’ll learn how to programmatically change the frame state of a JFrame component in a Swing application. The JFrame states are represented as a bitwise masks. You can minimize, maximize or make the JFrame state to normal, using the JFrame.setExtendedState() method.

You can pass the following values as the parameter to the method:

  • Frame.NORMAL
  • Frame.ICONIFIED
  • Frame.MAXIMIZED_HORIZ
  • Frame.MAXIMIZED_VERT
  • Frame.MAXIMIZED_BOTH
package org.kodejava.swing;

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

public class SwingFrameState extends JFrame {
    public SwingFrameState() throws HeadlessException {
        initUI();
    }

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

    private void initUI() {
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new FlowLayout());

        final JButton minimize = new JButton("Minimize");
        final JButton maximize = new JButton("Maximize");
        final JButton normal = new JButton("Normal");

        add(normal);
        add(minimize);
        add(maximize);

        pack();
        setSize(500, 200);

        ActionListener listener = e -> {
            if (e.getSource() == normal) {
                setExtendedState(Frame.NORMAL);
            } else if (e.getSource() == minimize) {
                setExtendedState(Frame.ICONIFIED);
            } else if (e.getSource() == maximize) {
                setExtendedState(Frame.MAXIMIZED_BOTH);
            }
        };

        minimize.addActionListener(listener);
        maximize.addActionListener(listener);
        normal.addActionListener(listener);
    }
}

The screenshot of the output from the code snippet above is:

Change JFrame State Programmatically

Change JFrame State Programmatically