How do I get file’s last modification date?

By Wayan in Core API, IO 0 Comment

To get file last modification date we can use the lastModified() method of the File class. This method returns a long value. After getting this value you can create an instance of java.util.Date class and pass this value as the parameter. This Date will hold the file’s last modification date.

package org.kodejava.io;

import java.io.File;
import java.util.Date;

public class FileLastModificationDate {
    public static void main(String[] args) {
        // Create an instance of file object.
        File file = new File("README.md");
        if (file.exists()) {
            // Get the last modification information.
            long lastModified = file.lastModified();

            // Create a new date object and pass last modified
            // information to the date object.
            Date date = new Date(lastModified);

            // We know when the last time the file was modified.
            System.out.println(date);
        }
    }
}

How do I convert decimal to hexadecimal?

By Wayan in Core API, Lang Package 0 Comment

To convert decimal number (base 10) to hexadecimal number (base 16) we can use the Integer.toHexString() method. This method takes an integer as parameter and return a string that represent the number in hexadecimal.

To convert back the number from hexadecimal to decimal number we can use the Integer.parseInt() method. This method takes two argument, the number to be converted, which is the string that represent a hexadecimal number. The second argument is the radix, we pass 16 which tell the method if the string is a hexadecimal number.

package org.kodejava.lang;

public class ToHexadecimalExample {
    public static void main(String[] args) {
        // Converting a decimal value to its hexadecimal representation 
        // can be done using Integer.toHexString() method.
        System.out.println(Integer.toHexString(1976));

        // On the other hand to convert hexadecimal string to decimal
        // we can use Integer.parseInt(string, radix) method, 
        // where radix for hexadecimal is 16.
        System.out.println(Integer.parseInt("7b8", 16));
    }
}

How do I read image file?

By Wayan in AWT, Core API 0 Comment

Here you see a code sample to read an image file. This code will work either the image file is located in a file folder or inside a jar file. You can use javax.imageio.ImageIO class to read the image file.

package org.kodejava.awt;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.InputStream;

public class ReadingImage {
    public static void main(String[] args) {
        ReadingImage demo = new ReadingImage();
        demo.getImage();
    }

    public void getImage() {
        try {
            InputStream is = getClass().getResourceAsStream("/kodejava.png");
            BufferedImage image = ImageIO.read(is);

            // Do something with the image.
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

How do I get a localhost hostname?

By Wayan in Core API, Networking 0 Comment 
package org.kodejava.network;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class HostNameExample {
    public static void main(String[] args) {
        try {
            InetAddress address = InetAddress.getLocalHost();

            System.out.println("Hostname: " + address.getHostName());
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}

An example of output produce by the code snippet above is:

Hostname: Krakatau

How do I get a list of weekday names?

By Wayan in Core API, Text Package 0 Comment

The example code below helps you to get all weekday names as an array of string. The first method, getWeekdays() return the full name string while the second method getShortWeekdays() return the short name of the weekday.

package org.kodejava.text;

import java.text.DateFormatSymbols;

public class WeekdayNames {
    public static void main(String[] args) {
        DateFormatSymbols dfs = new DateFormatSymbols();

        String[] weekdays = dfs.getWeekdays();
        for (String weekday : weekdays) {
            System.out.println("weekday = " + weekday);
        }

        String[] shortWeekdays = dfs.getShortWeekdays();
        for (String shortWeekday : shortWeekdays) {
            System.out.println("shortWeekday = " + shortWeekday);
        }
    }
}

The results of the code above are:

weekday = 
weekday = Sunday
weekday = Monday
weekday = Tuesday
weekday = Wednesday
weekday = Thursday
weekday = Friday
weekday = Saturday
shortWeekday = 
shortWeekday = Sun
shortWeekday = Mon
shortWeekday = Tue
shortWeekday = Wed
shortWeekday = Thu
shortWeekday = Fri
shortWeekday = Sat