Containers

As discussed earlier a container is a component that can be nested. The most widely used Panel is the Class Panel which can be extended further to partition GUIs. There is a Panel which is used for running the programs. This Panel is known as Class Applet

Containers

Common Container Methods

All the subclasses of the Container class inherit the behavior of more than 50 common methods of Container. These subclasses of the container mostly override the method of component. Some of the methods of container which are most widely used are as follow:

getComponents();
add();
getComponentCount();
getComponent(int);

ScrollPane

The ScrollPane container provides an automatic scrolling of any larger component which was introduced with the 1.1 release of the Java Runtime Environment (JRE). Any image which is bigger in size for the display area or a bunch of spreadsheet cells is considered as a large object. Moreover there is no LayoutManager for a ScrollPane because only a single object exists within it. However, the mechanism of Event Handling is being managed for scrolling.

The example below shows the Scrollpane. This scrollpane demonstrates the scrolling of the large image. In the program code below, first of all we have created a scrollpane by creating its object, then we have passed the parameter of image in it. We have also set the border layout as centre, as shown.


import java.awt.*; 

import java.applet.*; 

 

class Scrollpane extends Component { 

  private Image image; 

  public Scrollpane(Image m) { 

  image = m; 

  } 

  public void paint(Graphics g) { 

  if (image != null) 

  g.drawImage(image, 0, 0, this); 

  } 

} 

 

public class ScrollingImageDemo extends Applet { 

  public void init() { 

  setLayout(new BorderLayout()); 

  ScrollPane SC = new ScrollPane(ScrollPane.SCROLLBARS_ALWAYS); 

  Image mg = getImage(getCodeBase(), "cute-puppy.gif"); 

  SC.add(new Scrollpane(mg)); 

  add(SC, BorderLayout.CENTER); 

  } 

}

Here is the output:

C:\newprgrm>javac ScrollingImageDemo.java

C:\newprgrm>appletviewer ScrollingImageDemo.html

Download this example.

Containers

Containers

Containers

Tutorials