Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

BlockingQueue thread-safe?

Posted on 2013-11-06
2
Medium Priority
?
490 Views
Last Modified: 2013-11-21
Am I passing the BlockingQueue to frame2 properly?
Am I utilizing BlockingQueue in a thread-safe way?

frame1.java....

package package1;

import java.awt.BorderLayout;

public class frame1 extends JFrame {

	private JPanel contentPane;
	private BlockingQueue<String> queue = new ArrayBlockingQueue<String>(10);
	private JTextField textField;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					frame1 frame = new frame1();
					frame.setVisible(true);
					frame.Go();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}

		
		});
	}

	private void Go() {
		// TODO Auto-generated method stub
		SwingWorker<String,String> sw = new SwingWorker<String,String>() {

			@Override
			protected String doInBackground() throws Exception {
				// TODO Auto-generated method stub
				while(true)
					{
					publish(queue.take());
					}

			}

			@Override
			protected void done() {
				// TODO Auto-generated method stub
				super.done();
			}

			@Override
			protected void process(List<String> arg0) {
				// TODO Auto-generated method stub
				textField.setText(arg0.get(0));
				super.process(arg0);
			}
		};
		sw.execute();
		
	}

	/**
	 * Create the frame.
	 */
	public frame1() {
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 450, 300);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		contentPane.setLayout(new BorderLayout(0, 0));
		setContentPane(contentPane);
		
		JPanel panel = new JPanel();
		contentPane.add(panel, BorderLayout.CENTER);
		
		textField = new JTextField();
		panel.add(textField);
		textField.setColumns(10);
		
		JButton btnLaunchFrame = new JButton("Launch frame2");
		btnLaunchFrame.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				frame2 f = new frame2(queue);
				f.setVisible(true);
			}
		});
		panel.add(btnLaunchFrame);
	}

}

Open in new window


frame2.java...

package package1;

import java.awt.BorderLayout;

public class frame2 extends JFrame {

	private JPanel contentPane;


	/**
	 * Create the frame.
	 */
	public frame2(final BlockingQueue<String> queue) {
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 244, 146);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		contentPane.setLayout(new BorderLayout(0, 0));
		setContentPane(contentPane);
		
		JPanel panel = new JPanel();
		contentPane.add(panel, BorderLayout.CENTER);
		
		JButton btnClose = new JButton("Close and update queue");
		btnClose.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent arg0) {
				try {
					queue.put("hello");
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				setVisible(false);
			}
		});
		panel.add(btnClose);
	}

}

Open in new window

0
Comment
Question by:pdering
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 36

Expert Comment

by:mccarl
ID: 39629033
Am I passing the BlockingQueue to frame2 properly?
Yes, that appears fine to me.

Am I utilizing BlockingQueue in a thread-safe way?
Yes, that also is fine. The idea of a BlockingQueue is to be able to use it across multiple threads in the way that you have done.
0
 
LVL 28

Accepted Solution

by:
dpearson earned 2000 total points
ID: 39629085
I agree this code looks basically fine.

One small suggestion is to consider using:

poll()

instead of:

take()

You may find it makes shutdown easier to handle.

E.g. You could have poll() with a timeout of 1 second and then check to see if a flag is set to indicate "shutdown please".  If not, then loop around and wait for the next object.

take() blocks forever, so the only way to handle shutdown there is either to completely kill the thread (not always what you want) or use a custom 'shutdown' task that you add to the queue - although that won't be seen until all other tasks ahead of it are completed.

As I say, just something to consider.

Doug
0

Featured Post

VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

After being asked a question last year, I went into one of my moods where I did some research and code just for the fun and learning of it all.  Subsequently, from this journey, I put together this article on "Range Searching Using Visual Basic.NET …
Java had always been an easily readable and understandable language.  Some relatively recent changes in the language seem to be changing this pretty fast, and anyone that had not seen any Java code for the last 5 years will possibly have issues unde…
Viewers learn about the “for” loop and how it works in Java. By comparing it to the while loop learned before, viewers can make the transition easily. You will learn about the formatting of the for loop as we write a program that prints even numbers…
Viewers learn how to read error messages and identify possible mistakes that could cause hours of frustration. Coding is as much about debugging your code as it is about writing it. Define Error Message: Line Numbers: Type of Error: Break Down…

610 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question