Java Exception and Error handling

what are the four access modifiers available in hava and what is their significance in term of class, method, and variable accessibility

In Java, there are four access modifiers that control the visibility and accessibility of classes, methods, and variables. These modifiers are:

1. public

2. protected

3. default (also known as package-private, which is the absence of an explicit modifier)

4. private

public

• Classes: A class declared as public can be accessed from any other class in any package.

• Methods and Variables: Methods and variables declared as public can be accessed from any other class in any package.

protected

• Classes: The protected modifier cannot be applied to classes (top-level classes).

• Inner Classes: Inner classes (nested classes) can be declared as protected.

• Methods and Variables: Methods and variables declared as protected can be accessed within the same package and by subclasses in different packages.

• default (package-private)

  • Classes: A class with no explicit access modifier is accessible only within the same package.

  • Methods and Variables: Methods and variables with no explicit access modifier are accessible only within the same package.

• private

  • Classes: The private modifier cannot be applied to top-level classes.

  • Inner Classes: Inner classes (nested classes) can be declared as private.

  • Methods and Variables: Methods and variables declared as private can be accessed only within the same class in which they are declared.

• 2. what is difference between exception and error

• In Java, both Exception and Error are subclasses of the Throwable class, but they represent different types of issues that can occur during the execution of a program. Here are the key differences between Exception and Error:

• Exception

  Definition:

  1. • An Exception represents conditions that a reasonable application might want to catch and handle.

Error

Definition:

1. • An Error represents serious problems that a reasonable application should not try to catch. These are typically external to the application and often represent catastrophic failures.

3. what is difference between checked exception and unchecked exception

In Java, exceptions are categorized into two main types: checked exceptions and unchecked exceptions. The difference between these two types lies primarily in how they are handled by the Java compiler and the programmer's responsibility in dealing with them.

Checked Exceptions

1. Definition:

   • Checked exceptions are exceptions that are checked at compile-time. The compiler ensures that these exceptions are either caught or declared in the method signature using the throws keyword.

2. Handling:

   • The programmer is required to handle checked exceptions explicitly. This can be done using a try-catch block or by declaring the exception in the method's throws clause.

3. Examples:

   • IOException: Thrown when an input-output operation fails or is interrupted.

   • SQLException: Thrown when there is a database access error.

   • ClassNotFoundException: Thrown when an application tries to load a class through its string name but no definition for the class with the specified name could be found.

4. Usage:

   • Checked exceptions are typically used for recoverable conditions where the program can take some action to recover from the exception.

Unchecked Exceptions

1. Definition:

   • Unchecked exceptions are exceptions that are not checked at compile-time. These exceptions are subclasses of RuntimeException and Error.

2. Handling:

   • The programmer is not required to handle unchecked exceptions explicitly. These exceptions can be caught, but it is not mandatory to declare them in the method signature.

3. Examples:

   • NullPointerException: Thrown when an application attempts to use null in a case where an object is required.

   • ArrayIndexOutOfBoundsException: Thrown to indicate that an array has been accessed with an illegal index.

   • ArithmeticException: Thrown when an exceptional arithmetic condition has occurred, such as division by zero.

4. Usage:

   • Unchecked exceptions typically indicate programming errors, such as logic errors or improper use of an API. These are generally conditions that the application cannot recover from or that are the result of a bug in the code.

• 4. write a java program that reads user input for two integers and performs division. Handle the exception that is thrown when the second number is zero and display an error message to the user

• 

  5. writ ethe code of arrayindexoutofboundsexeption&singleindexoutofboundsexception