Thread: Drawing a string without use of Main(String[] args)

Basically I have this code and another program that rotates text around the screen and I'm trying to merge them. How do I draw a string to this code without the use of something like

public static void main( String args[] ) //
{ //
(new ViewOfDisplay()).setVisible(true); // Start application
}

I can't change the barebones of the code, just add to

package Clients;
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
 
import java.util.List;
import java.util.Map;
import java.util.Observer;
import java.util.Observable;
 
import Middle.*;
 
class ViewOfDisplay implements Observer
{
  private static final int H = 300;       // Height of window pixels
  private static final int W = 400;       // Width  of window pixels
 
  public ViewOfDisplay( RootPaneContainer rpc )
  {
    // Add code to setup a graphical view of the display
  }
 
 
 
  public void update( Observable aModelOfDisplay, Object arg )
  {
     // Code to update the graphical display with the current
     //  state of the system
     //  Orders awaiting processing
     //  Orders being picked in the 'warehouse. 
     //  Orders awaitig collection
  }
 
 
}

This is the rotating text program

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
 
// Note Menu bar is at the top of the area 
 
class Main
{
  public static void main( String args[] )  // 
  {                                         // 
    (new Application()).setVisible(true);   // Start application 
  }                                         // 
}
 
class Application extends JFrame
{
  private static final int H = 300;         // Height of window 
  private static final int W = 400;         // Width  of window 
 
  private Animate animation;                // Active object 
  private String  message = 
          "Rotating message ";
  private Font font =
       new Font("Monospaced",Font.BOLD,24);
 
  public Application()
  {
    setSize( W, H );                        // Size of drawing area 
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    animation = new Animate();              // Start chimney smoking 
    animation.start();
  }
 
  public void update( Graphics g )          // Called by repaint 
  {                                         // 
    drawScreen( (Graphics2D) g );           // Draw Screen 
  }
 
  public void paint( Graphics g )           // When 'Window' is first 
  {                                         //  shown or damaged 
    drawScreen( (Graphics2D) g );           // Draw Screen 
  }
 
  private Dimension     theAD;              // Alternate Dimension 
  private BufferedImage theAI;              // Alternate Image 
  private Graphics2D    theAG;              // Alternate Graphics 
 
  public void drawScreen( Graphics2D g )    // Double buffer 
  {                                         //  allow resize 
    Dimension d    = getSize();             // Size of image 
 
    if (  ( theAG == null )  ||
          ( d.width  != theAD.width ) ||
          ( d.height != theAD.height ) )
    {                                       // New size 
      theAD = d;
      theAI = (BufferedImage) createImage( d.width, d.height );
      theAG = theAI.createGraphics();
      AffineTransform at = new AffineTransform();
      at.setToIdentity();
      at.scale( ((double)d.width)/W, ((double)d.height)/H );
      theAG.transform(at);
    }
 
    drawActualScreen( theAG );               // Draw actual screen 
    g.drawImage( theAI, 0, 0, this );
  }
 
  public void drawActualScreen( Graphics2D g )// Actual draw screen 
  {
    g.setPaint( Color.white );              // Paint Colour 
    g.fill( new Rectangle2D.Double( 0, 0, W, H ) );
 
    g.setPaint( Color.black );              // Paint Colour 
    g.setFont ( font );
 
    FontMetrics fm = getFontMetrics( font );
    int width = fm.stringWidth(message);
 
    int offset = animation.getPos();
 
    g.drawString( message, offset, 100 );
    g.drawString( message, W + offset, 100 );
  }
 
  class Animate extends Thread
  {
    private int       pos = 1;              // 
 
    public synchronized int getPos()
    {
      return pos;
    }
 
    public synchronized void moveString()   // Move string 
    {
      pos--;                                //  New position 
      if ( pos < -W ) pos = 0;
    }
 
    public void run()                       // Active part 
    {
      while ( true )                        // Forever 
      {                                     // 
        try                                 // 
        {                                   // 
          moveString();                     //  Move mess 
          repaint();                        //   -> update 
          Thread.sleep( 25 );               //  Sleep 
        }                                   // loop 
        catch (InterruptedException e) {}   // Ignore any error 
      }
    }
  }
 
}

The program needs either an explicit main method or an implicit one (such as with an applet) in order to run. I know of no way around this other than using a static initializer kludge.

I think I may be mistaken on that one. I thought that you could get some code up and running from a static initializer block without a main, but on looking into this, I'm not so sure any more.

Maybe they changed something with 7.

--- Update ---

According to the (unchanged) documentation for the java executable it "launches a Java application. It does this by starting a Java runtime environment, loading a specified class, and invoking that class's main method".

So does the following wrok?

public class Silly {
    static {
        Silly app = new Silly();
        app.displayWhy();
            // We exit before the java executable gets a chance to complain
            // about not finding main()
        System.exit(666);
    }
 
    void displayWhy() {
        System.out.println("Because we can!");
    }
}

It's fine in 6 update 26, but results in an error in 7.