How do I check if a message is loggable?

By I Wayan Saryada in Logging 0 Comment

The Logger class provide a setLevel() method to set the logging level. By setting logging to a certain level we can control which message will be logged.

To determine or check if a message will be logged we can use the Logger.isLoggable(Level level) method. Let see the example below.

package org.kodejava.util.logging;

import java.util.logging.Logger;
import java.util.logging.Level;

public class LoggingLevelCheck {
    public static void main(String[] args) {
        // Obtains an instance of Logger and set the logging level to 
        // Level.WARNING.
        Logger log = Logger.getLogger(LoggingLevelCheck.class.getName());
        log.setLevel(Level.WARNING);

        // Log INFO level message. This message will not be logged due to
        // the log level set to Level.WARNING
        if (log.isLoggable(Level.INFO)) {
            log.info("Application Information Message");
        }

        // Log WARNING level message when Level.WARNING is loggable.
        if (log.isLoggable(Level.WARNING)) {
            log.warning("Application Warning Information");
        }

        // Log SEVERE level message when Level.SEVERE is loggable.
        if (log.isLoggable(Level.SEVERE)) {
            log.severe("Information Severe Information");
        }
    }
}

This will result only the Level.WARNING and Level.SEVERE messages are logged.

Oct 07, 2021 8:18:03 PM org.kodejava.util.logging.LoggingLevelCheck main
WARNING: Application Warning Information
Oct 07, 2021 8:18:03 PM org.kodejava.util.logging.LoggingLevelCheck main
SEVERE: Information Severe Information

How do I obtain or create a Logger?

By I Wayan Saryada in Logging 0 Comment

Since JDK 1.4 a logging API was introduced into the Java class libraries. This API enables our application to logs some messages to record our application activities.

To create an instance of Logger we can call the Logger.getLogger() factory method which will return the available logger for the given namespace, or it will create a new one when it doesn’t exist.

package org.kodejava.util.logging;

import java.util.logging.Logger;

public class LoggingDemo {
    public static void main(String[] args) {
        // Obtaining an instance of Logger. This will create a new Logger
        // is it doesn't exist.
        Logger log = Logger.getLogger(LoggingDemo.class.getName());

        // Log some message using a different type of severity level.
        log.info("Info Message");
        log.warning("Warning Message");
        log.severe("Severe Message");
        log.config("Config Message");
        log.fine("Fine Message");
        log.finer("Finer Message");
        log.finest("Finest Message");
    }
}

After we create the Logger instance we can create a message log by calling the logging method such as info(String message), warning(String message) and severe(String message). Below are some message produces by the Logger.

Oct 07, 2021 8:13:48 PM org.kodejava.util.logging.LoggingDemo main
INFO: Info Message
Oct 07, 2021 8:13:48 PM org.kodejava.util.logging.LoggingDemo main
WARNING: Warning Message
Oct 07, 2021 8:13:48 PM org.kodejava.util.logging.LoggingDemo main
SEVERE: Severe Message

How do I create a compound border?

By I Wayan Saryada in Swing 0 Comment

In this example we create a compound border, a border around border. Here, instead of creating a new instance of Border class directly we create the border using the BorderFactory factory class.

package org.kodejava.swing;

import javax.swing.*;
import javax.swing.border.BevelBorder;
import javax.swing.border.Border;
import java.awt.*;

public class CompoundBorderExample extends JFrame {
    public CompoundBorderExample() {
        initializeUI();
    }

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

    private void initializeUI() {
        setSize(500, 500);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new FlowLayout(FlowLayout.LEFT));

        BevelBorder raisedBevel =
                (BevelBorder) BorderFactory.createBevelBorder(BevelBorder.RAISED);
        BevelBorder loweredBevel =
                (BevelBorder) BorderFactory.createBevelBorder(BevelBorder.LOWERED);
        Border border = BorderFactory.createCompoundBorder(raisedBevel, loweredBevel);
        JPanel panel = new JPanel();
        panel.setBorder(border);

        setContentPane(panel);
    }
}

How do I add a title to a border?

By I Wayan Saryada in Swing 0 Comment

This example shows you how to create a border that have a title in it. There is a special border class the TitledBorder that does this. We can define the justification of the title, left, centered or right justify. To do this we call the setTitleJustification() method. We can also set other attributes such as font or the title position.

package org.kodejava.swing;

import javax.swing.*;
import javax.swing.border.TitledBorder;
import java.awt.*;

public class TitledBorderExample extends JFrame {
    public TitledBorderExample() {
        initializeUI();
    }

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

    private void initializeUI() {
        setSize(500, 500);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new FlowLayout(FlowLayout.LEFT));

        TitledBorder border = new TitledBorder(" Form Data ");
        border.setTitleJustification(TitledBorder.LEFT);
        border.setTitlePosition(TitledBorder.TOP);

        JPanel panel = new JPanel();
        panel.setBorder(border);
        panel.setLayout(new GridLayout(1, 2));

        JLabel usernameLabel = new JLabel("Username: ");
        JTextField usernameField = new JTextField();
        panel.add(usernameLabel);
        panel.add(usernameField);

        setContentPane(panel);
    }
}

How do I create Border for swing component?

By I Wayan Saryada in Swing 0 Comment

This example shows how we can create border for swing components. In the example below we set border of a JPanel component. Some border implementation that we use below including LineBorder, BevelBorder, EtchedBorder and MatteBorder.

package org.kodejava.swing;

import javax.swing.*;
import javax.swing.border.LineBorder;
import javax.swing.border.BevelBorder;
import javax.swing.border.EtchedBorder;
import javax.swing.border.MatteBorder;
import java.awt.*;

public class BorderDemo extends JFrame {
    public BorderDemo() {
        initializeUI();
    }

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

    private void initializeUI() {
        setSize(400, 400);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLayout(new BorderLayout(15, 15));

        JPanel top = new JPanel();
        top.setBorder(new LineBorder(Color.RED, 1, true));

        JPanel bottom = new JPanel();
        bottom.setBorder(new BevelBorder(BevelBorder.LOWERED));

        JPanel left = new JPanel();
        left.setBorder(new EtchedBorder(EtchedBorder.RAISED));

        JPanel right = new JPanel();
        right.setBorder(new MatteBorder(5, 5, 5, 5, Color.BLUE));

        JPanel center = new JPanel();
        center.setBorder(new BevelBorder(BevelBorder.RAISED));

        getContentPane().add(top, BorderLayout.NORTH);
        getContentPane().add(bottom, BorderLayout.SOUTH);
        getContentPane().add(left, BorderLayout.WEST);
        getContentPane().add(right, BorderLayout.EAST);
        getContentPane().add(center, BorderLayout.CENTER);
    }
}