Java Language Internal Exceptions

Exception Classes in java.lang:

• Java defines several exception classes in the java.lang package, many of them are subclasses of RuntimeException.
• Exceptions in java.lang are automatically imported into any Java program.

Unchecked Exceptions:

• These include common errors such as NullPointerException, ArrayIndexOutOfBoundsException, and ArithmeticException.
• They do not need to be declared in the throws clause of the methods, as the compiler does not require specific treatment for these exceptions.

Examples of unchecked exceptions:
ArithmeticException: calculation error such as division by zero.
NullPointerException: use of null reference.
ClassCastException: Invalid class conversion attempt.
NumberFormatException: error converting String to a number.

Checked Exceptions:
They need to be listed in throws if the method can throw them.
They are mandatory for exceptions that the compiler requires handling, as they cannot be ignored.

Examples of checked exceptions:
ClassNotFoundException: class not found.
IllegalAccessException: access denied to a class.
InterruptedException: interruption of a thread by another thread.
NoSuchMethodException: requested method does not exist.

Chained Exceptions:
Introduced in Java 1.4 to specify one exception as the cause of another.
They allow you to associate an original exception with the generated exception, useful in scenarios with layers of errors.

Constructors for chained exceptions:
Throwable(Throwable cause): defines the causing exception.
Throwable(String msg, Throwable cause): allows you to add a descriptive message.

Methods:
getCause(): returns the cause of the current exception.
initCause(Throwable cause): defines the cause after the exception was created.

Considerations about Chained Exceptions:
Useful when knowledge of the root cause helps to understand the error.
Not every program needs to use chained exceptions, but they offer an elegant solution for complex scenarios.

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