![Exceptions in Java
An exception is an unwanted or unexpected event, which occurs during the
execution of a program i.e. at run time, that disrupts the normal flow of the
program’s instructions.
6
public class A{
public static void main(String args[])
{
int a=2, b=0, c;
c=a/b; //Exception
System.out.println(c);
}
}](https://image.slidesharecdn.com/javaprogramming1-190516113434/85/Java-Exception-Handling-and-Applets-6-320.jpg)
![Exception Handling Java(Example)
package ExceptionHandling;
public class Exception {
public static void main(String args[]) {
try {
int c=100/0;
}catch(ArithmeticException e) {
System.out.println("Exception caught");
}
}
}
12](https://image.slidesharecdn.com/javaprogramming1-190516113434/85/Java-Exception-Handling-and-Applets-12-320.jpg)
![References
Head First Java, 2nd Edition [Book] - O'Reilly Media
http://javatpoint.com/java-tutorial
https://www.geeksforgeeks.org/java/
http://www.programmingtutorials.com/java.aspx
22](https://image.slidesharecdn.com/javaprogramming1-190516113434/85/Java-Exception-Handling-and-Applets-22-320.jpg)
Java Exception Handling and Applets
- 1. Java Exception Handling & Applets Presented By Tanmoy Roy 1 Roll : 34801216001
- 2. Content Introduction Exception Handling Exceptions in Java Hierarchy of Java Exception classes Types of Exceptions Exception Handling Java Java Applet What is Applet? Advantage & Drawback of Applet Some Important Points on Java Applet Lifecycle of Java Applet 2
- 3. Some Interesting Facts about Java The initial name of java was “Oak”. it had been modified to Java by Sun’s marketing department once they found that name was already registered for a computer company. Java is the second preferred language and is incredibly popular among the developers. Java does not support the concept of pointer. Java is used by 95% of the companies as their primary language. Which is much more than C and other languages. 3
- 4. Introduction The Exception Handling in Java is one amongst the powerful mechanism to handle the runtime errors so traditional flow of the program will be maintained. Applet is a special type of program that is embedded in the webpage to generate the dynamic content. 4
- 6. Exceptions in Java An exception is an unwanted or unexpected event, which occurs during the execution of a program i.e. at run time, that disrupts the normal flow of the program’s instructions. 6 public class A{ public static void main(String args[]) { int a=2, b=0, c; c=a/b; //Exception System.out.println(c); } }
- 7. Hierarchy of Java Exception classes 7
- 8. Types of Exceptions 8 The classes which directly inherit Throwable class except RuntimeException and Error are known as checked exceptions The classes which inherit RuntimeException are known as unchecked exceptions These are not exceptions at all, but problems that arise beyond the control of the user or the programmer.
- 9. Types of Exceptions 9 unchecked exceptions checked exceptions Error
- 10. Exception Handling Java 10 Exception Handling mechanism follows a flow which is depicted in the below figure. But if an exception is not handled, it may lead to a system failure. That is why handling an exception is very important.
- 11. Exception Handling Java Keyword Description try The "try" keyword is used to specify a block where we should place exception code. The try block must be followed by either catch or finally. catch The "catch" block is used to handle the exception. It must be preceded by try block finally The "finally" block is used to execute the important code of the program. It is executed whether an exception is handled or not. throw The "throw" keyword is used to throw an exception. throws The "throws" keyword is used to declare exceptions. It doesn't throw an exception. 11
- 12. Exception Handling Java(Example) package ExceptionHandling; public class Exception { public static void main(String args[]) { try { int c=100/0; }catch(ArithmeticException e) { System.out.println("Exception caught"); } } } 12
- 13. Java Applet 13
- 14. What is Applet? An applet is a Java program that runs in a Web browser. An applet can be a fully functional Java application because it has the entire Java API at its disposal. 14
- 15. Advantage & Drawback of Applet Advantage of Applet It works at client side so less response time. Secured It can be executed by browsers running under many platforms, including Linux, Windows, Mac OS etc. Drawback of Applet Plugin is required at client browser to execute applet. 15
- 16. Some Important Points on Java Applet All applets are sub-classes (either directly or indirectly) of java.applet.Applet class. Applets are not stand-alone programs. Instead, they run within either a web browser or an applet viewer. JDK provides a standard applet viewer tool called applet viewer. In general, execution of an applet does not begin at main() method. Output of an applet window is not performed by System.out.println(). Rather it is handled with various AWT methods, such as drawString(). 16
- 17. Lifecycle of Java Applet 17
- 18. Lifecycle methods for Applet 18 init( ) destroy( ) start( ) paint( ) stop( )
- 19. Lifecycle methods for Applet(Cont.) 19 init( ) destroy( ) start( ) paint( ) stop( ) is used to initialized the Applet. It is invoked only once. is used to destroy the Applet. It is invoked only once. is invoked after the init() method or browser is maximized. It is used to start the Applet is used to paint the Applet. It provides Graphics class object. is used to stop the Applet. It is invoked when Applet is stop or browser is minimized.
- 20. A "Hello, World" Applet import java.applet.*; import java.awt.*; public class HelloWorldApplet extends Applet { public void paint (Graphics g) { g.drawString ("Hello World", 25, 50); } } 20 <html> <title>The Hello, World Applet</title> <hr> <applet code = "HelloWorldApplet.class" width = "320" height = "120"> </applet> <hr> </html> HelloWorldApplet.java HelloWorldApplet.html
- 21. Conclusion Exceptions are used to improve error efficiency. The Exception Handling in Java is one of the powerful mechanism to handle the runtime errors. Applet is a Java program that can be embedded into a web page. It runs inside the web browser and works at client side. 21
- 22. References Head First Java, 2nd Edition [Book] - O'Reilly Media http://javatpoint.com/java-tutorial https://www.geeksforgeeks.org/java/ http://www.programmingtutorials.com/java.aspx 22
- 23. Thank You 23