How do I replace text in the JTextArea?

By Wayan in Swing 0 Comment

In this example you’ll see how to use the replaceRange(String str, int start, int end) method to replace a string in the JTextArea from the start position to the end position with the specified string.

package org.kodejava.swing;

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

public class TextAreaReplaceText extends JPanel {
    public TextAreaReplaceText() {
        initializeUI();
    }

    public static void showFrame() {
        JPanel panel = new TextAreaReplaceText();
        panel.setOpaque(true);

        JFrame frame = new JFrame("JTextArea Demo");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setContentPane(panel);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(TextAreaReplaceText::showFrame);
    }

    private void initializeUI() {
        String text = "The quick white fox jumps over the sleepy dog.";

        JTextArea textArea = new JTextArea(text);
        textArea.setLineWrap(true);
        textArea.setWrapStyleWord(true);
        JScrollPane scrollPane = new JScrollPane(textArea);

        textArea.replaceRange("brown", 10, 15);
        textArea.replaceRange("lazy", 35, 41);

        this.setPreferredSize(new Dimension(500, 200));
        this.setLayout(new BorderLayout());
        this.add(scrollPane, BorderLayout.CENTER);
    }
}

The screenshot of the code snippet above is:

JTextArea Replace Text Demo

How do I use join method to wait for threads to finish?

By Wayan in Core API, Lang Package 0 Comment

If you want a thread to work until another thread dies, you can join the thread onto the end of the another thread using the join() method. For example, you want thread B only work until thread A completes its work, then you want thread B to join thread A.

package org.kodejava.example.lang;

public class ThreadJoin implements Runnable {
    private int numberOfLoop;

    private ThreadJoin(int numberOfLoop) {
        this.numberOfLoop = numberOfLoop;
    }

    public void run() {
        System.out.println("[" +
            Thread.currentThread().getName() + "] - Running.");

        for (int i = 0; i < this.numberOfLoop; i++) {
            System.out.println("[" +
                Thread.currentThread().getName() + "] " + i);
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        System.out.println("[" +
            Thread.currentThread().getName() + "] - Done.");
    }

    public static void main(String[] args) {
        Thread t1 = new Thread(new ThreadJoin(10), "FirstThread");
        Thread t2 = new Thread(new ThreadJoin(20), "SecondThread");

        try {
            // start t1 and waits for this thread to die before
            // starting the t2 thread.
            t1.start();
            t1.join();

            // start t2
            t2.start();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

How do I set the priority of a thread?

By Wayan in Core API, Lang Package 0 Comment

Threads always run with some priority, usually represented as a number between 1 and 10 (although in some cases the range is less than 10). A thread gets a default priority that is the priority of the thread of execution that creates it.

But, you can also set a thread’s priority directly by calling the setPriority() method on a Thread instance. One thing to remember about thread priorities is never rely on thread priorities, because thread-scheduling priority behavior is not guaranteed.

package org.kodejava.lang;

public class ThreadPriority extends Thread {
    private final String threadName;

    ThreadPriority(String threadName) {
        this.threadName = threadName;
    }

    public static void main(String[] args) {
        ThreadPriority thread1 = new ThreadPriority("First");
        ThreadPriority thread2 = new ThreadPriority("Second");
        ThreadPriority thread3 = new ThreadPriority("Third");
        ThreadPriority thread4 = new ThreadPriority("Fourth");
        ThreadPriority thread5 = new ThreadPriority("Fifth");

        // set thread1 to minimum priority = 1
        thread1.setPriority(Thread.MIN_PRIORITY);

        // set thread2 to priority 2
        thread2.setPriority(2);

        // set thread3 to normal priority = 5
        thread3.setPriority(Thread.NORM_PRIORITY);

        // set thread4 to priority 8
        thread4.setPriority(8);

        // set thread5 to maximum priority = 10
        thread5.setPriority(Thread.MAX_PRIORITY);

        thread1.start();
        thread2.start();
        thread3.start();
        thread4.start();
        thread5.start();
    }

    @Override
    public void run() {
        System.out.println("Running [" + threadName + "]");
        for (int i = 1; i <= 10; i++) {
            System.out.println("[" + threadName + "] => " + i);

            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

How do I get the currently executing thread?

By Wayan in Core API, Lang Package 0 Comment

To get the currently executing thread, use the static currentThread() method of the Thread class. This method returns a reference of the currently executing thread object.

package org.kodejava.lang;

public class GetCurrentThreadDemo {
    public static void main(String[] args) {
        // Get the currently executing thread object
        Thread thread = Thread.currentThread();
        System.out.println("Id      : " + thread.getId());
        System.out.println("Name    : " + thread.getName());
        System.out.println("Priority: " + thread.getPriority());
    }
}

The code snippet print the following output:

Id      : 1
Name    : main
Priority: 5

How do I set and get the name of a thread?

By Wayan in Core API, Lang Package 0 Comment

You can assign a name to thread instance by using the setName() method and get the name of the thread using the getName() method. The naming support is also available as a constructor of the Thread class such as Thread(String name) and Thread(Runnable target, String name).

package org.kodejava.lang;

public class ThreadNameDemo extends Thread {
    public ThreadNameDemo() {
    }

    public ThreadNameDemo(String name) {
        super(name);
    }

    public static void main(String[] args) {
        Thread thread1 = new ThreadNameDemo();
        thread1.setName("FOX");
        thread1.start();

        Thread thread2 = new ThreadNameDemo("DOG");
        thread2.start();
    }

    @Override
    public void run() {
        // Call getName() method to get the thread name of this
        // thread object.
        System.out.println("Running [" + this.getName() + "]");
    }
}