How do I get Applet’s document URL?

By I Wayan Saryada in Applet, Core API 0 Comment

The code snippet below show you how to get the URL of the document (HTML, JSP, etc.) where the Applet is embedded. To obtain this document URL we use the getDocumentBase() method call provided by the Applet class.

In the paint() method below we use the getDocumentBase() to create a URL as a link to an image to be displayed by our applet.

package org.kodejava.applet;

import java.applet.Applet;
import java.awt.*;

public class AppletDocumentBase extends Applet {
    private Image logo;

    @Override
    public void init() {
        // Locates logo image base on the URL of the document
        // where the Applet is embedded which is returned by
        // the getDocumentBase() method call.
        //
        // eg. http://localhost:8080/images/logo.jpg
        logo = getImage(getDocumentBase(), "/images/logo.png");
    }

    @Override
    public void paint(Graphics g) {
        g.setColor(Color.black);
        g.drawRect(0, 0, getWidth() - 1, getHeight() - 1);

        // Draw the logo image on the Applet surface.
        g.drawImage(logo, 10, 10, this);
    }
}
** Deprecated: The Applet API is deprecated since JDK 9, no replacement.

How do I move directory to another directory with its entire contents?

By I Wayan Saryada in Apache Commons, Commons IO 3 Comments

Below is an example to move one directory with all its child directory and files to another directory. We can use the FileUtils.moveDirectory() method to simplify the process.

package org.kodejava.commons.io;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;

public class DirectoryMove {
    public static void main(String[] args) {
        String source = "F:/Temp/source";
        File srcDir = new File(source);

        String destination = "F:/Temp/target";
        File destDir = new File(destination);

        try {
            // Move the source directory to the destination directory.
            // The destination directory must not exist prior to the
            // move process.
            FileUtils.moveDirectory(srcDir, destDir);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.16.1</version>
</dependency>

Maven Central

How do I copy directory with all its contents to another directory?

By I Wayan Saryada in Apache Commons, Commons IO 0 Comment

To copy a directory with the entire child directories and files we can use a handy method provided by the Apache Commons IO FileUtils.copyDirectory(). This method accepts two parameters, the source directory and the destination directory. The source directory should be available while if the destination directory doesn’t exist, it will be created.

package org.kodejava.commons.io;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;

public class DirectoryCopy {
    public static void main(String[] args) {
        // An existing directory to copy.
        String source = "F:/Temp/source";
        File srcDir = new File(source);

        // The destination directory to copy to. This directory
        // doesn't exist and will be created during the copy
        // directory process.
        String destination = "F:/Temp/target";
        File destDir = new File(destination);

        try {
            // Copy source directory into destination directory
            // including its child directories and files. The
            // destination directory will be created if it does
            // not exist. This copy processes also preserve the
            // date information of the file.
            FileUtils.copyDirectory(srcDir, destDir);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.16.1</version>
</dependency>

Maven Central

How do I copy a URL into a file?

By I Wayan Saryada in Apache Commons, Commons IO 6 Comments

The code snippet below shows you how to use the FileUtils.copyURLToFile(URL, File) method of the Apache Commons IO library to help you to copy the contents of a URL directly into a file.

package org.kodejava.commons.io;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URL;

public class URLToFile {
    public static void main(String[] args) {
        try {
            URL url = URI.create("https://www.google.com").toURL();
            File destination = new File("google.html");

            // Copy bytes from the URL to the destination file.
            FileUtils.copyURLToFile(url, destination);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.16.1</version>
</dependency>

Maven Central

How do I set the maximum rows to read in a query?

By I Wayan Saryada in JDBC 0 Comment

If you want to limit the result of your query, you can call the Statement.setMaxRows(int max) method. This call will allow the ResultSet object contains a maximum number of records specified in the parameter of the setMaxRows method.

Another way to limit the number of data returned in a query is to use the database-specific command such as the MySQL limit command.

package org.kodejava.jdbc;

import java.sql.*;

public class SetMaxRowExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {
            Statement statement = connection.createStatement();

            // Executes an SQL query to get the total number of data
            // in product table.
            String query = "select count(*) from product";
            ResultSet rs = statement.executeQuery(query);

            while (rs.next()) {
                System.out.println("Total Products: " + rs.getInt(1));
            }

            // Set the maximum row of data that can be stored in the
            // ResultSet.
            statement.setMaxRows(5);

            // Executes an SQL query to retrieve data from product
            // table.
            query = "select id, code, name, price from product";
            rs = statement.executeQuery(query);

            System.out.println("Data read after the MaxRows is set.");
            while (rs.next()) {
                System.out.println("ID: " + rs.getInt("id")
                                   + ", CODE: " + rs.getString("code")
                                   + ", NAME: " + rs.getString("name")
                                   + ", PRICE: " + rs.getBigDecimal("price"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

When running the code, we’ll see that only 5 records were read from the product table instead of 10 records. This is the result of setting the maximum rows in the Statement object.

Below is the output of our code.

Total Products: 9
Data read after the MaxRows is set.
ID: 1, CODE: P0000001, NAME: UML Distilled 3rd Edition, PRICE: 25.00
ID: 3, CODE: P0000003, NAME: PHP Programming, PRICE: 20.00
ID: 4, CODE: P0000004, NAME: Longman Active Study Dictionary, PRICE: 40.00
ID: 5, CODE: P0000005, NAME: Ruby on Rails, PRICE: 24.00
ID: 6, CODE: P0000006, NAME: Championship Manager, PRICE: 0.00

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.4.0</version>
</dependency>

Maven Central