How do I create a thread by implementing Runnable interface?

By Wayan in Core API, Lang Package 0 Comment

Here is the second way for creating a thread. We create an object that implements the java.lang.Runnable interface. For another example see How do I create a thread by extending Thread class?.

package org.kodejava.lang;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class TimeThread implements Runnable {
    private final DateFormat df = new SimpleDateFormat("hh:mm:ss");

    // The run() method will be invoked when the thread of this runnable object
    // is started.
    @Override
    public void run() {
        while (true) {
            Calendar calendar = Calendar.getInstance();
            System.out.format("Now is: %s.%n", df.format(calendar.getTime()));

            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        TimeThread time = new TimeThread();

        Thread thread = new Thread(time);
        thread.start();
    }
}

An example result of this code are:

Now is: 07:18:39.
Now is: 07:18:40.
Now is: 07:18:41.
Now is: 07:18:42.
Now is: 07:18:43.

How do I create a thread by extending Thread class?

By Wayan in Core API, Lang Package 0 Comment

There are two ways that we can use tho create a thread. First is by extending the java.lang.Thread class and the second way is by creating a class that implements the java.lang.Runnable interface. See How do I create a thread by implementing Runnable interface?

In this example we’ll extend the Thread class. To run a code in a thread we need to provide the run() method in our class. Let’s see the code below.

package org.kodejava.lang;

public class NumberPrinter extends Thread {
    private final String threadName;
    private final int delay;

    public NumberPrinter(String threadName, int delay) {
        this.threadName = threadName;
        this.delay = delay;
    }

    // The run() method will be invoked when the thread is started.
    @Override
    public void run() {
        for (int i = 0; i < 10; i++) {
            System.out.println("Thread [" + threadName + "] = " + i);

            try {
                Thread.sleep(delay);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        NumberPrinter printerA = new NumberPrinter("A", 1000);
        NumberPrinter printerB = new NumberPrinter("B", 750);

        printerA.start();
        printerB.start();
    }
}

The example result of our code is:

Thread [B] = 0
Thread [A] = 0
Thread [B] = 1
Thread [A] = 1
Thread [B] = 2
Thread [A] = 2
Thread [B] = 3
Thread [B] = 4
Thread [A] = 3
Thread [B] = 5
Thread [A] = 4
Thread [B] = 6
Thread [A] = 5
Thread [B] = 7
Thread [B] = 8
Thread [A] = 6
Thread [B] = 9
Thread [A] = 7
Thread [A] = 8
Thread [A] = 9

How do I compare two dates?

By Wayan in Core API, Util Package 0 Comment

In this example you’ll see the utilization of SimpleDateFormat class for comparing two dates for equality. We convert the date object into string using the DateFormat instance and then compare it using String.equals() method.

package org.kodejava.util;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class ComparingDate {
    public static void main(String[] args) {
        // Create a SimpleDateFormat instance with dd/MM/yyyy format
        DateFormat df = new SimpleDateFormat("dd/MM/yyyy");

        // Get the current date
        Date today = new Date();

        // Create an instance of calendar that represents a new year date
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DATE, 1);
        calendar.set(Calendar.MONTH, Calendar.JANUARY);
        calendar.set(Calendar.YEAR, 2021);

        String newYear = df.format(calendar.getTime());
        String now = df.format(today);

        // Using the string equals method we can compare the date.
        if (now.equals(newYear)) {
            System.out.println("Happy New Year!");
        } else {
            System.out.println("Have a nice day!");
        }
    }
}

How do I search for files recursively using Apache Commons IO?

By Wayan in Apache Commons, Commons IO 0 Comment

This example demonstrates how we can use the FileUtils class listFiles() method to search for a file specified by their extensions. We can also define to find the file recursively deep down into the subdirectories.

package org.kodejava.commons.io;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.util.Collection;

public class SearchFileRecursive {
    public static void main(String[] args) {
        File root = new File("F:/Wayan/Kodejava/kodejava-example");

        try {
            String[] extensions = {"xml", "java", "dat"};

            // Find files within a root directory and optionally its
            // subdirectories, which match an array of extensions. When the
            // extensions are null, all files will be returned.
            //
            // This method will return matched file as java.io.File
            Collection<File> files = FileUtils.listFiles(root, extensions, true);

            for (File file : files) {
                System.out.println("File = " + file.getAbsolutePath());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.14.0</version>
</dependency>

Maven Central

How do I delete file from FTP server?

By Wayan in Apache Commons, Commons Net 0 Comment

This example demonstrates how to delete file from FTP server.

package org.kodejava.commons.net;

import org.apache.commons.net.ftp.FTPClient;

import java.io.IOException;

public class FTPDeleteDemo {
    public static void main(String[] args) {
        FTPClient client = new FTPClient();

        try {
            client.connect("ftp.example.com");
            client.login("demo", "password");

            // Delete file on the FTP server. When the FTP delete
            // process completes, it returns true.
            String filename = "data.txt";
            boolean deleted = client.deleteFile(filename);
            if (deleted) {
                System.out.printf("File %s was deleted...", filename);
            } else {
                System.out.println("No file was deleted...");
            }

            client.logout();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                client.disconnect();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>commons-net</groupId>
    <artifactId>commons-net</artifactId>
    <version>3.10.0</version>
</dependency>

Maven Central