How do I remove leading and trailing white space from string?

By Wayan in Core API, Lang Package 0 Comment 
package org.kodejava.lang;

public class TrimStringExample {
    public static void main(String[] args) {
        String text = "     tattarrattat     ";
        System.out.println("Original      = " + text);
        System.out.println("text.length() = " + text.length());

        // The trim() method will result a new string object with a leading and
        // trailing while space removed.
        text = text.trim();
        System.out.println("Result        = " + text);
        System.out.println("text.length() = " + text.length());
    }
}

The result of the code snippet above:

Original      =      tattarrattat     
text.length() = 22
Result        = tattarrattat
text.length() = 12

How do I format a number with leading zeros?

By Wayan in Core API, Text Package 0 Comment

This example give you an example using java.text.DecimalFormat class to add leading zeros to a number. For another method you can read the see the earlier example on How do I add leading zeros to a number?.

package org.kodejava.text;

import java.text.DecimalFormat;
import java.text.NumberFormat;

public class NumberFormatLeadingZerosExample {
    public static void main(String[] args) {
        NumberFormat formatter = new DecimalFormat("0000000");
        String number = formatter.format(2500);

        System.out.println("Number with leading zeros: " + number);
    }
}

The result of code snippet above:

Number with leading zeros: 0002500

How do I add leading zeros to a number?

By Wayan in Core API, Lang Package 1 Comment

This example shows you how to use the String.format() method to add zero padding to a number. If you just want to print out the result you can use System.out.format(). This method is available since Java 1.5, so If you use a previous version you can use the NumberFormat class, see: How do I format a number with leading zeros?.

package org.kodejava.lang;

public class LeadingZerosExample {
    public static void main(String[] args) {
        int number = 1500;

        // String format below will add leading zeros (the %0 syntax)
        // to the number above. The length of the formatted string will
        // be 7 characters.
        String formatted = String.format("%07d", number);

        System.out.println("Number with leading zeros: " + formatted);
    }
}

Here is the result of the code snippet above:

Number with leading zeros: 0001500

For more information about the format syntax you can find it here.

How do I create a batch update in JDBC?

By Wayan in JDBC 0 Comment

A batch statement can be used to execute multiple update commands as single unit in a database manipulation. This statement in the database is not executed one by one but as a single execution instead. In some cases, using a batch update can be more efficient than to execute the commands separately.

In this example, you are shown how to create a batch command to insert some products into a database table.

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Arrays;

public class JDBCBatchExample {
    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)) {

            // Turn of the auto-commit mode
            connection.setAutoCommit(false);

            try (Statement statement = connection.createStatement()) {
                // And some batch to insert some product information into
                // the product table
                statement.addBatch("INSERT INTO product (code, name) " +
                                   "VALUE ('P0000006', 'Championship Manager')");
                statement.addBatch("INSERT INTO product (code, name) " +
                                   "VALUE ('P0000007', 'Transport Tycoon Deluxe')");
                statement.addBatch("INSERT INTO product (code, name) " +
                                   "VALUE ('P0000008', 'Roller Coaster Tycoon 3')");
                statement.addBatch("INSERT INTO product (code, name) " +
                                   "VALUE ('P0000009', 'Pro Evolution Soccer')");

                // To execute a batch command, we must call the executeBatch()
                // method.
                int[] updateCounts = statement.executeBatch();
                System.out.println("updateCounts = " + Arrays.toString(updateCounts));

                // Commit our transaction
                connection.commit();
            } catch (SQLException e) {
                connection.rollback();
                e.printStackTrace();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

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

Maven Central

How do I read an applet parameters?

By Wayan in Applet, Core API 0 Comment 
package org.kodejava.applet;

import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;

public class AppletParameterExample extends Applet {
    private String name = "";

    public void init() {
        // Here we read a parameter named name from the applet tag definition
        // in our html file.
        name = getParameter("name");
    }

    public void paint(Graphics g) {
        g.setColor(Color.BLUE);
        g.drawString("Hello " + name + ", Welcome to the Applet World.", 0, 0);
    }
}

Now we have the applet code ready. To enable the web browser to execute the applet create the following html page.

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Parameterized Applet</title>
</head>
<body>
<applet code="org.kodejava.applet.AppletParameterExample"
        height="150" width="350">
    <param name="name" value="Mr. Bean"/>
</applet>
</body>
</html>
** Deprecated: The Applet API is deprecated since JDK 9, no replacement.