Exceptions and Collections

Exceptions

Exceptions are events that occur during execution and break the normal flow of the program.

Handling with try-catch-finally

try {
    int result = 10 / 0;
} catch (ArithmeticException e) {
    System.out.println("Error: You cannot divide by zero.");
} finally {
    System.out.println("This code always runs.");
}

• Checked: The compiler forces you to handle them (for example, IOException).
• Unchecked: Logical errors (for example, NullPointerException).

Collections

They are structures that allow us to manage groups of objects flexibly (unlike arrays).

• Lists (ArrayList): Allow duplicate elements and keep order.
• Sets: Do not allow duplicates.
• Maps: Store key-value pairs.

List<String> names = new ArrayList<>();
names.add("Java");
names.add("Spring");