How do I create a simple JTable component?

The code snippet presented below shows you how to create a simple JTable component in a swing application. To create a JTable component we initialize it using the constructor that accept two parameters.

The first parameter is the table’s row of data which type is Object[][], a two-dimensional array of Object. The second parameter is the table’s column names which type is Object[], an array of object.

After the JTable instance is created we place it inside a scroll pane component which in turn is added to the frame’s content pane.

package org.kodejava.swing;

import javax.swing.*;
import java.awt.*;
import java.text.MessageFormat;
import java.util.Calendar;

public class SimpleJTableDemo extends JFrame {
    public SimpleJTableDemo() throws HeadlessException {
        initializeUI();
    }

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

    private void initializeUI() {
        // Defines table's column names.
        String[] columnNames = {
                "ID", "Name", "Date of Birth", "Sex"
        };

        // Defines table's data.
        Object[][] rowData = {
                {1, "Alice", createDOB(1980, Calendar.JANUARY, 1), "F"},
                {2, "Bob", createDOB(1982, Calendar.JUNE, 21), "M"},
                {3, "Carol", createDOB(1970, Calendar.OCTOBER, 12), "M"},
                {4, "Mallory", createDOB(1988, Calendar.FEBRUARY, 19), "M"}
        };

        // Initializes an instance of JTable and specifies the table
        // data and column names. Then we place the table in a scroll pane.
        JTable table = new JTable(rowData, columnNames);
        JScrollPane pane = new JScrollPane(table);

        // Sets the frame setting.
        setTitle("Simple JTable Demo");
        setSize(new Dimension(500, 500));
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        getContentPane().add(pane, BorderLayout.CENTER);
    }

    private String createDOB(int year, int month, int day) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(year, month, day);
        return MessageFormat.format("{0,date,dd-MMM-yyyy}", calendar.getTime());
    }
}

When we run the program we will see the following result:

Simple JTable Demo

Simple JTable Demo

How do I format a message that contains number information?

This example show you how to use java.text.MessageFormat class to format a message that contains numbers.

package org.kodejava.text;

import java.text.MessageFormat;
import java.util.Locale;

public class MessageFormatNumber {
    public static void main(String[] args) {

        // Set the Locale for the MessageFormat.
        Locale.setDefault(Locale.US);

        // Use the default formatting for number.
        String message = MessageFormat.format("This is a {0} and {1} numbers",
                10, 75);
        System.out.println(message);

        // This line has the same format as above.
        message = MessageFormat.format("This is a {0,number} and {1,number} " +
                "numbers", 10, 75);
        System.out.println(message);

        // Format a number with 2 decimal digits.
        message = MessageFormat.format("This is a formatted {0, number,#.##} " +
                "and {1, number,#.##} numbers", 25.7575, 75.2525);
        System.out.println(message);

        // Format a number as currency.
        message = MessageFormat.format("This is a formatted currency " +
                        "{0,number,currency} and {1,number,currency} numbers",
                25.7575, 25.7575);
        System.out.println(message);

        // Format numbers in percentage.
        message = MessageFormat.format("This is a formatted percentage " +
                "{0,number,percent} and {1,number,percent} numbers", 0.10, 0.75);
        System.out.println(message);
    }
}

The result of the program are the following lines:

This is a 10 and 75 numbers
This is a 10 and 75 numbers
This is a formatted 25.76 and 75.25 numbers
This is a formatted currency $25.76 and $25.76 numbers
This is a formatted percentage 10% and 75% numbers

How do I format a message that contains time information?

Here we demonstrate how to use the java.text.MessageFormat class to format a message contains a time information.

package org.kodejava.text;

import java.util.Date;
import java.util.Calendar;
import java.util.Locale;
import java.text.MessageFormat;

public class MessageFormatTime {
    public static void main(String[] args) {
        Date today = new Date();
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.HOUR, 7);

        Date nextWeek = calendar.getTime();

        // We want the message to be is Locale.US
        Locale.setDefault(Locale.US);

        // Format a time including date information.
        String message = MessageFormat.format("Now is {0} and the next " +
                "7 hours is {1}", today, nextWeek);
        System.out.println(message);

        // Format a time and display only the time portion
        message = MessageFormat.format("Now is {0, time} and the next " +
                "7 hours is {1, time}", today, nextWeek);
        System.out.println(message);

        // Format a time using a short format (e.g. HH:mm am/pm)
        message = MessageFormat.format("Now is {0, time, short} and " +
                "the next 7 hours is {1, time, short}", today, nextWeek);
        System.out.println(message);

        // Format a time using a medium format (eg. HH:mm:ss am/pm).
        message = MessageFormat.format("Now is {0, time, medium} and " +
                "the next 7 hours is {1, time, medium}", today, nextWeek);
        System.out.println(message);

        // Format a time using a long format (e.g. HH:mm:ss am/pm TIMEZONE).
        message = MessageFormat.format("Now is {0, time, long} and the " +
                "next 7 hours is {1, time, long}", today, nextWeek);
        System.out.println(message);

        // Format a time using a full format (e.g. HH:mm:ss am/pm TIMEZONE).
        message = MessageFormat.format("Now is {0, time, full} and the " +
                "next 7 hours is {1, time, full}", today, nextWeek);
        System.out.println(message);

        // Format a time using a custom pattern.
        message = MessageFormat.format("Now is {0, time, HH:mm:ss.sss} " +
                "and the next 7 hours is {1, time, HH:mm:ss.sss}", today, nextWeek);
        System.out.println(message);
    }
}

The above program produces:

Now is 10/8/21, 9:38 PM and the next 7 hours is 10/9/21, 4:38 AM
Now is 9:38:10 PM and the next 7 hours is 4:38:10 AM
Now is 9:38 PM and the next 7 hours is 4:38 AM
Now is 9:38:10 PM and the next 7 hours is 4:38:10 AM
Now is 9:38:10 PM CST and the next 7 hours is 4:38:10 AM CST
Now is 9:38:10 PM China Standard Time and the next 7 hours is 4:38:10 AM China Standard Time
Now is  21:38:10.010 and the next 7 hours is  04:38:10.010

How do I format a message that contains date information?

This example demonstrate how you can use the java.text.MessageFormat class to format a message with a date information in it.

package org.kodejava.text;

import java.util.Date;
import java.util.Calendar;
import java.util.Locale;
import java.text.MessageFormat;

public class MessageFormatDate {
    public static void main(String[] args) {
        Date today = new Date();
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.DATE, 7);

        Date nextWeek = calendar.getTime();

        // We want the message to be is Locale.US
        Locale.setDefault(Locale.US);

        // Format a date, the time value is included
        String message = MessageFormat.format("Today is {0} and next " +
                "week is {1}", today, nextWeek);
        System.out.println(message);

        // Format a date and display only the date portion
        message = MessageFormat.format("Today is {0,date} and next " +
                "week is {1,date}", today, nextWeek);
        System.out.println(message);

        // Format a date using a short format (e.g. dd/MM/yyyy)
        message = MessageFormat.format("Today is {0,date,short} and " +
                "next week is {1,date,short}", today, nextWeek);
        System.out.println(message);

        // Format a date using a medium format, it displays the month long-name,
        // but using a two digit date and year.
        message = MessageFormat.format("Today is {0,date,medium} and " +
                "next week is {1,date,medium}", today, nextWeek);
        System.out.println(message);

        // Format a date using a long format, two digit for date, a long month
        // name and a four digit year.
        message = MessageFormat.format("Today is {0,date,long} and " +
                "next week is {1,date,long}", today, nextWeek);
        System.out.println(message);

        // Format a date using a full format, the same as above plus a full day
        // name.
        message = MessageFormat.format("Today is {0,date,full} and " +
                "next week is {1,date,full}", today, nextWeek);
        System.out.println(message);

        // Format a date using a custom pattern.
        message = MessageFormat.format("Today is {0,date,dd-MM-yyyy} and " +
                "next week is {1,date,dd-MM-yyyy}", today, nextWeek);
        System.out.println(message);
    }
}

The above program produces:

Today is 10/8/21, 9:35 PM and next week is 10/15/21, 9:35 PM
Today is Oct 8, 2021 and next week is Oct 15, 2021
Today is 10/8/21 and next week is 10/15/21
Today is Oct 8, 2021 and next week is Oct 15, 2021
Today is October 8, 2021 and next week is October 15, 2021
Today is Friday, October 8, 2021 and next week is Friday, October 15, 2021
Today is 08-10-2021 and next week is 15-10-2021