Instantiated components from within a thread aren’t repainting into a JFrame in Java

[Rigoberto Vides]

Hi guys, I'm making this tetris variation, a piece should be spawned every 2 secs. I try to construct this piece (Block) from within a thread like this:

     public void run()
    {
     public void run()
    {
        while(true)
        {
            SwingUtilities.invokeLater(
                    new Runnable()
                    {
                        public void run()
                        {
                            int index = Block.getRandomStartPosition();
                            new Thread(new Block(frame, index)).start();
                            new Thread(new Block(frame, index+1)).start();
                        }
                    });

            try
            {
                Thread.sleep(timeToSpawn);
            }
            catch(InterruptedException e)
            {
                //Unhandled exception
            }
        }
    }

I'm using swingUtilities.invokeLater to send this thread to the swing event dispatcher, everything looks to work normal (i.e. the blocks instantiate each timeToSpawn) milisecs... but there is one BIG problem: they don't show on the Jframe! On the other hand whenever I just instantiate 1 or n blocks from within the same JFrame class like this for example:

private void CreateBlocks()
{
new Thread(new Block(this, index)).start();
new Thread(new Block(this, index+1)).start();
}

They work perfectly fine and paint on the JFrame. What a mess.. I've been like crazy figuring out what's happening! My Block class extends Component and implements Runnable, it's run method looks like this:

public void run()
    {
        while(true)
        {
            try
            {
               Thread.sleep(450);
            }
            catch(InterruptedException e)
            {
                //Unhandled exception
            }

            //Check if I'm ready to fall, otherwise check me as grounded
            connectMy4Sides();
            
            //Make this cube "fall"
            if(!this.Grounded())
            {
                //visual
                yPosition += yoffset;

                //logical
                Grid.cells[currentRow][currentColumn].setMyBlock(null);
                currentRow++;
                Grid.cells[currentRow][currentColumn].setMyBlock(this);

            }

            connectMy4Sides();

            repaint();

        }

    }

It's a thread to update it's position each 450 milisecs... could this be the problem? although as I mentioned before, I just test this code and it worked, the problem is when I instantiate an object of this class within another thread.

As final and extra info. whenever I check the method toString on the Instantiated cubes from threads, they give me this [,0,0,0x0], but when I instantiate them within the same JFrame class they give me this result [,0,0,328x552] and they appear on the frame. this 328x552 value it's the same as the component's Dimension returned by getPreferredSize()... I tried to force them to that dimension by instantiate them like this:

   new Block(this, index).setPreferredSize(new Dimension(328, 552));  

But it didn't work, anyone knows what this [,0,0,328x552] value could mean?

Thanks in advance Everyone!

[Bear Bibeault]

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