Friday, February 2, 2007

What is the base class for all swing components ?

JComponent (except top-level containers)

SOURCE : www.referjava.com

What is Difference between AWT and Swing ?

Posted: Tue Jan 30, 2007 12:17 pm Post subject: What is Difference between AWT and Swing ?

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Swing provides a richer set of components than AWT. They are 100% Java-based. AWT on the other hand was developed with the mind set that if a component or capability of a component weren’t available on one platform, it wouldn’t be available on any platform. Due to the peer-based nature of AWT, what might work on one implementation might not work on another, as the peer-integration might not be as robust. There are a few other advantages to Swing over AWT:


Swing provides both additional components and added functionality to AWT-replacement components
Swing components can change their appearance based on the current "look and feel" library that's being used.
Swing components follow the Model-View-Controller (MVC) paradigm, and thus can provide a much more flexible UI.
Swing provides "extras" for components, such as:
Icons on many components
Decorative borders for components
Tool tips for components
Swing components are lightweight (less resource intensive than AWT)
Swing provides built-in double buffering
Swing provides paint debugging support for when you build your own components

Swing also has a few disadvantages:


It requires Java 2 or a separate JAR file
If you're not very careful when programming, it can be slower than AWT (all components are drawn)
Swing components that look like native components might not act exactly like native components


SOURCE : www.referjava.com

Why do you Canvas ?

The Canvas class of java.awt is used to provide custom drawing and event handling. It provides a general GUI component for drawing images and text on the screen. It does not support any drawing methods of its own, but provides access to a Graphics object through its paint() method. The paint() method is invoked upon the creation and update of a canvas so that the Graphics object associated with a Canvas object can be updated.


SOURCE : www.referjava.com

Why do you Canvas ?

The Canvas class of java.awt is used to provide custom drawing and event handling. It provides a general GUI component for drawing images and text on the screen. It does not support any drawing methods of its own, but provides access to a Graphics object through its paint() method. The paint() method is invoked upon the creation and update of a canvas so that the Graphics object associated with a Canvas object can be updated.


SOURCE : www.referjava.com

Why do you Canvas ?

The Canvas class of java.awt is used to provide custom drawing and event handling. It provides a general GUI component for drawing images and text on the screen. It does not support any drawing methods of its own, but provides access to a Graphics object through its paint() method. The paint() method is invoked upon the creation and update of a canvas so that the Graphics object associated with a Canvas object can be updated.


SOURCE : www.referjava.com

What are 4 drivers available in JDBC ?

Type 1: JDBC-ODBC Bridge
The type 1 driver, JDBC-ODBC Bridge, translates all JDBC calls into ODBC (Open DataBase Connectivity) calls and sends them to the ODBC driver. As such, the ODBC driver, as well as, in many cases, the client database code, must be present on the client machine. May be used when an ODBC driver has already been installed on client machine and performance is not an issue.
Type 2: Native-API/partly Java driver
JDBC driver type 2 -- the native-API/partly Java driver -- converts JDBC calls into database-specific calls for databases such as SQL Server, Informix, Oracle, or Sybase. The type 2 driver communicates directly with the database server; therefore it requires that some binary code be present on the client machine. Can be used when application is not for internet.
Type 3: Net-protocol/all-Java driver
JDBC driver type 3 -- the net-protocol/all-Java driver -- follows a three-tiered approach whereby the JDBC database requests are passed through the network to the middle-tier server. The middle-tier server then translates the request (directly or indirectly) to the database-specific native-connectivity interface to further the request to the database server. If the middle-tier server is written in Java, it can use a type 1 or type 2 JDBC driver to do this.Type 3 drivers are best suited for environments that need to provide connectivity to a variety of DBMS servers and heterogeneous databases and that require significantly high levels of concurrently connected users where performance and scalability are major concerns.
Type 4: Native-protocol/all-Java driver
The native-protocol/all-Java driver (JDBC driver type 4) converts JDBC calls into the vendor-specific database management system (DBMS) protocol so that client applications can communicate directly with the database server. Level 4 drivers are completely implemented in Java to achieve platform independence and eliminate deployment administration issues. Useful for Internet-related applications.

SOURCE : www.referjava.com

Where the CardLayout is used ?

CardLayout manages two or more components that share the same display space. It lets you use one container (usually a panel) to display one out of many possible component children (like flipping cards on a table). A program can use this layout to show a different child component to different users. For example, the interface shown to an administrator might have additional functionality from the interface shown to a regular user. With card layout, our program can show the appropriate interface depending on the type of user using the program. Another typical use of card layout would be to let end user toggle among different displays and choose the one they prefer. In this case, the program must provide a GUI for the user to make the selection.

SOURCE : www.referjava.com