What is it called when you instantiate an object within a method's ( )?

[John Quach]

Here is the code. In the Slideshow class, the init() has JApplet and its object in the ( ). I didn't know you can instantiate inside the ( ).
What kind of technique is that?

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

public class SlideShow extends JPanel implements Runnable
{
	int SPEED = 1000;
	Image[] photos;
	ImageIcon icon;
	JLabel imgLabel;
	int currentIndex = 0;
	Thread runner;
	
	/// class and object in here?!
	public void init( JApplet app)
	{
		photos = new Image[3];
		photos[0] = app.getImage( app.getCodeBase(), "b1.JPG");
		photos[1] = app.getImage( app.getCodeBase(), "b2.JPG");
		photos[2] = app.getImage( app.getCodeBase(), "b3.JPG");
		icon = new ImageIcon();
		imgLabel = new JLabel();
		imgLabel.setHorizontalAlignment( JLabel.CENTER);
		setupIcon( 0 );
		add( imgLabel);
		runner = new Thread( this);
		runner.start();
	}
	public void setupIcon( int index)
	{
		currentIndex = index;
		icon.setImage( photos[index]);
		imgLabel.setIcon( icon);
		validate();
	}
	public void run()
	{
		try
		{
			while( true )
			{
				if(currentIndex == photos.length-1)
					setupIcon( 0 );
				else
					setupIcon( currentIndex+1);
				
				repaint();
				Thread.sleep( SPEED);
			}
			
		}
		catch( InterruptedException ie ){}
		
	}
	
	
	
}


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

public class SlideShowMain extends JApplet
{
	SlideShow myslideshow;
	public void init()
	{
		myslideshow = new SlideShow();
		myslideshow.init( this);
		setLayout( new FlowLayout());
		add( myslideshow);
	}

}

[John Jai]

JApplet app refers to a reference of JApplet class. This is just a parameter of the method as you see in any other methods. The app variable is similar to the name variable below.

void print(String name)
{
      System.out.println(name);
}

Instead of a String reference, you are passing a JApplet reference as an input argument to the method init() in the SlideShow class.

This method is called from the SlideShowMain class using the code -

myslideshow.init( this);  

So the object that is currently referenced in the SlideShowMain class is passed as the argument to init() method in the SlideShow class. And since SlideShowMain extends JApplet, a JApplet reference can refer to SlideShowMain object.

[Campbell Ritchie]

Do you really mean instantiate inside the ()? Or do you mean refer to?

[Greg Brannon]

I assume he's referring to line 71:

setLayout( new FlowLayout() );

Does that technique have a name?

[Campbell Ritchie]

Greg Brannon wrote: . . . Does that technique have a name?

I think it’s called using an anonymous object.