Which is an exception in java?

Spike 180 Published: 07/20/2024

Which is an exception in java?

A question about Java exceptions!

In Java, there are several types of exceptions that can occur during the execution of a program. These exceptions are not part of the normal flow of a program's execution and can be handled or propagated by using try-catch blocks.

Here are some examples of exceptions in Java:

ArithmeticException: This exception is thrown when an arithmetic operation (like division by zero) is attempted. For example, int x = 5 / 0; will throw an ArithmeticException. ArrayIndexOutOfBoundsException: This exception is thrown when an array index is out of range. For example, int[] arr = new int[5]; System.out.println(arr[6]); will throw an ArrayIndexOutOfBoundsException because the maximum valid index for an array of size 5 is 4. ClassCastException: This exception is thrown when the runtime system attempts to cast an object to a subclass of which it is not an instance. For example, String s = (Integer) "Hello"; will throw a ClassCastException because a String cannot be cast to an Integer. NullPointerException: This exception is thrown when an application attempts to use a null object reference. For example, String str = null; System.out.println(str.length()); will throw a NullPointerException because you can't call methods on a null object. IOException: This exception is thrown by input/output operations (like reading or writing files) when there's an error. For example, trying to read from a file that doesn't exist will throw an IOException.

RuntimeException: This is the superclass of most exceptions in Java and is typically used for runtime errors like NullPointerException or ArrayIndexOutOfBoundsException.

Error: This is the superclass of RuntimeException and is typically used for severe error conditions that need to be caught.

When it comes to handling these exceptions, Java provides a try-catch block construct. The general syntax is:

try {

// code that may throw an exception


} catch (ExceptionType e) {


// code to handle the exception


}

In this block, the code in the try clause may throw an exception. If it does, the program will jump to the catch clause and execute the code there. The type of exception that can be caught is specified in the catch clause.

It's also worth noting that exceptions can be propagated up the call stack by not catching them. This means that if a method throws an exception and it's not caught, the method will exit and the exception will be passed to the next method in the call stack until it's either caught or the program exits.

In summary, Java has many types of exceptions that can occur during runtime, and handling them with try-catch blocks is crucial for writing robust and reliable code.

What are the six built in exceptions in Java?

I'm happy to help you with that!

In Java, there are six built-in exceptions that can be thrown by the Java Virtual Machine (JVM) and used by programmers to handle runtime errors or unexpected conditions. These exceptions are:

ArithmeticException: This exception is thrown when an invalid arithmetic operation occurs, such as dividing by zero.

For example:

int i = 5 / 0; // throws ArithmeticException
ArrayIndexOutOfBoundsException: This exception is thrown when trying to access an array element beyond the array's length or negative indices.

For example:

int[] arr = new int[5];

arr[-1] = 10; // throws ArrayIndexOutOfBoundsException
BooleanException: This exception is not actually used in Java, but it exists as a placeholder for future use. ClassCastException: This exception is thrown when the wrong type of object is assigned to a variable or passed as an argument to a method that expects a specific type of object.

For example:

List list = new ArrayList<>();

list.add(new Integer(1)); // throws ClassCastException
IndexOutOfBoundsException: This exception is thrown when trying to access an array or string using an index that is out of bounds (i.e., beyond the last element or before the first element).

For example:

String str = "Hello";

char c = str.charAt(10); // throws IndexOutOfBoundsException
NullPointerException: This exception is thrown when trying to access a null object reference or null pointer.

For example:

String s = null;

System.out.println(s.length()); // throws NullPointerException

These built-in exceptions can be caught and handled using Java's try-catch blocks, allowing your program to recover from unexpected situations. It's essential to understand and work with these exceptions effectively to write robust and error-free code.

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